WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [patch 22/24] Xen-paravirt_ops: Add the Xenbus sysfs and vir

To: Andi Kleen <ak@xxxxxx>
Subject: [Xen-devel] [patch 22/24] Xen-paravirt_ops: Add the Xenbus sysfs and virtual device hotplug driver.
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Wed, 21 Feb 2007 12:53:16 -0800
Cc: Zachary Amsden <zach@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Ian Pratt <ian.pratt@xxxxxxxxxxxxx>, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Chris Wright <chrisw@xxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxx, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
Delivery-date: Wed, 21 Feb 2007 13:10:56 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20070221205254.169835700@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: quilt/0.46-1
This communicates with the machine control software via a registry
residing in a controlling virtual machine. This allows dynamic
creation, destruction and modification of virtual device
configurations (network devices, block devices and CPUS, to name some
examples).

Signed-off-by: Ian Pratt <ian.pratt@xxxxxxxxxxxxx>
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 arch/i386/xen/Kconfig                     |    5
 drivers/xen/Makefile                      |    1
 drivers/xen/xenbus/Makefile               |    9
 drivers/xen/xenbus/xenbus_client.c        |  566 +++++++++++++++++
 drivers/xen/xenbus/xenbus_comms.c         |  218 ++++++
 drivers/xen/xenbus/xenbus_comms.h         |   44 +
 drivers/xen/xenbus/xenbus_probe.c         |  891 ++++++++++++++++++++++++++++
 drivers/xen/xenbus/xenbus_probe.h         |   72 ++
 drivers/xen/xenbus/xenbus_probe_backend.c |  269 ++++++++
 drivers/xen/xenbus/xenbus_xs.c            |  840 ++++++++++++++++++++++++++
 include/asm-i386/hypervisor.h             |    1
 include/xen/xenbus.h                      |  208 ++++++
 12 files changed, 3124 insertions(+)

===================================================================
--- a/arch/i386/xen/Kconfig
+++ b/arch/i386/xen/Kconfig
@@ -8,3 +8,8 @@ config XEN
        default y
        help
          This is the Linux Xen port.
+
+config XEN_BACKEND
+       bool
+       depends XEN
+       default n
===================================================================
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -1,2 +1,3 @@ obj-y   += core/
 obj-y  += core/
 obj-y  += console/
+obj-y  += xenbus/
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/Makefile
@@ -0,0 +1,9 @@
+obj-y  += xenbus.o
+
+xenbus-objs =
+xenbus-objs += xenbus_client.o
+xenbus-objs += xenbus_comms.o
+xenbus-objs += xenbus_xs.o
+xenbus-objs += xenbus_probe.o
+
+obj-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -0,0 +1,563 @@
+/******************************************************************************
+ * Client-facing interface for the Xenbus driver.  In other words, the
+ * interface between the Xenbus and the device-specific code, be it the
+ * frontend or the backend of that driver.
+ *
+ * Copyright (C) 2005 XenSource Ltd
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/event_channel.h>
+#include <xen/events.h>
+#include <xen/grant_table.h>
+#include <xen/xenbus.h>
+
+char *xenbus_strstate(enum xenbus_state state)
+{
+       static char *name[] = {
+               [ XenbusStateUnknown      ] = "Unknown",
+               [ XenbusStateInitialising ] = "Initialising",
+               [ XenbusStateInitWait     ] = "InitWait",
+               [ XenbusStateInitialised  ] = "Initialised",
+               [ XenbusStateConnected    ] = "Connected",
+               [ XenbusStateClosing      ] = "Closing",
+               [ XenbusStateClosed       ] = "Closed",
+       };
+       return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
+}
+EXPORT_SYMBOL_GPL(xenbus_strstate);
+
+/**
+ * xenbus_watch_path - register a watch
+ * @dev: xenbus device
+ * @path: path to watch
+ * @watch: watch to register
+ * @callback: callback to register
+ *
+ * Register a @watch on the given path, using the given xenbus_watch structure
+ * for storage, and the given @callback function as the callback.  Return 0 on
+ * success, or -errno on error.  On success, the given @path will be saved as
+ * @watch->node, and remains the caller's to free.  On error, @watch->node will
+ * be NULL, the device will switch to %XenbusStateClosing, and the error will
+ * be saved in the store.
+ */
+int xenbus_watch_path(struct xenbus_device *dev, const char *path,
+                     struct xenbus_watch *watch,
+                     void (*callback)(struct xenbus_watch *,
+                                      const char **, unsigned int))
+{
+       int err;
+
+       watch->node = path;
+       watch->callback = callback;
+
+       err = register_xenbus_watch(watch);
+
+       if (err) {
+               watch->node = NULL;
+               watch->callback = NULL;
+               xenbus_dev_fatal(dev, err, "adding watch on %s", path);
+       }
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_watch_path);
+
+
+/**
+ * xenbus_watch_path2 - register a watch on path/path2
+ * @dev: xenbus device
+ * @path: first half of path to watch
+ * @path2: second half of path to watch
+ * @watch: watch to register
+ * @callback: callback to register
+ *
+ * Register a watch on the given @path/@path2, using the given xenbus_watch
+ * structure for storage, and the given @callback function as the callback.
+ * Return 0 on success, or -errno on error.  On success, the watched path
+ * (@path/@path2) will be saved as @watch->node, and becomes the caller's to
+ * kfree().  On error, watch->node will be NULL, so the caller has nothing to
+ * free, the device will switch to %XenbusStateClosing, and the error will be
+ * saved in the store.
+ */
+int xenbus_watch_path2(struct xenbus_device *dev, const char *path,
+                      const char *path2, struct xenbus_watch *watch,
+                      void (*callback)(struct xenbus_watch *,
+                                       const char **, unsigned int))
+{
+       int err;
+       char *state = kasprintf(GFP_KERNEL, "%s/%s", path, path2);
+       if (!state) {
+               xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
+               return -ENOMEM;
+       }
+       err = xenbus_watch_path(dev, state, watch, callback);
+
+       if (err)
+               kfree(state);
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_watch_path2);
+
+
+/**
+ * xenbus_switch_state
+ * @dev: xenbus device
+ * @xbt: transaction handle
+ * @state: new state
+ *
+ * Advertise in the store a change of the given driver to the given new_state.
+ * Return 0 on success, or -errno on error.  On error, the device will switch
+ * to XenbusStateClosing, and the error will be saved in the store.
+ */
+int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
+{
+       /* We check whether the state is currently set to the given value, and
+          if not, then the state is set.  We don't want to unconditionally
+          write the given state, because we don't want to fire watches
+          unnecessarily.  Furthermore, if the node has gone, we don't write
+          to it, as the device will be tearing down, and we don't want to
+          resurrect that directory.
+
+          Note that, because of this cached value of our state, this function
+          will not work inside a Xenstore transaction (something it was
+          trying to in the past) because dev->state would not get reset if
+          the transaction was aborted.
+
+        */
+
+       int current_state;
+       int err;
+
+       if (state == dev->state)
+               return 0;
+
+       err = xenbus_scanf(XBT_NIL, dev->nodename, "state", "%d",
+                          &current_state);
+       if (err != 1)
+               return 0;
+
+       err = xenbus_printf(XBT_NIL, dev->nodename, "state", "%d", state);
+       if (err) {
+               if (state != XenbusStateClosing) /* Avoid looping */
+                       xenbus_dev_fatal(dev, err, "writing new state");
+               return err;
+       }
+
+       dev->state = state;
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_switch_state);
+
+int xenbus_frontend_closed(struct xenbus_device *dev)
+{
+       xenbus_switch_state(dev, XenbusStateClosed);
+       complete(&dev->down);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
+
+/**
+ * Return the path to the error node for the given device, or NULL on failure.
+ * If the value returned is non-NULL, then it is the caller's to kfree.
+ */
+static char *error_path(struct xenbus_device *dev)
+{
+       return kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
+}
+
+
+static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
+                               const char *fmt, va_list ap)
+{
+       int ret;
+       unsigned int len;
+       char *printf_buffer = NULL;
+       char *path_buffer = NULL;
+
+#define PRINTF_BUFFER_SIZE 4096
+       printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
+       if (printf_buffer == NULL)
+               goto fail;
+
+       len = sprintf(printf_buffer, "%i ", -err);
+       ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap);
+
+       BUG_ON(len + ret > PRINTF_BUFFER_SIZE-1);
+
+       dev_err(&dev->dev, "%s\n", printf_buffer);
+
+       path_buffer = error_path(dev);
+
+       if (path_buffer == NULL) {
+               dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
+                      dev->nodename, printf_buffer);
+               goto fail;
+       }
+
+       if (xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer) != 0) {
+               dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
+                      dev->nodename, printf_buffer);
+               goto fail;
+       }
+
+fail:
+       kfree(printf_buffer);
+       kfree(path_buffer);
+}
+
+
+/**
+ * xenbus_dev_error
+ * @dev: xenbus device
+ * @err: error to report
+ * @fmt: error message format
+ *
+ * Report the given negative errno into the store, along with the given
+ * formatted message.
+ */
+void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
+{
+       va_list ap;
+
+       va_start(ap, fmt);
+       xenbus_va_dev_error(dev, err, fmt, ap);
+       va_end(ap);
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_error);
+
+/**
+ * xenbus_dev_fatal
+ * @dev: xenbus device
+ * @err: error to report
+ * @fmt: error message format
+ *
+ * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
+ * xenbus_switch_state(dev, NULL, XenbusStateClosing) to schedule an orderly
+ * closedown of this driver and its peer.
+ */
+
+void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
+{
+       va_list ap;
+
+       va_start(ap, fmt);
+       xenbus_va_dev_error(dev, err, fmt, ap);
+       va_end(ap);
+
+       xenbus_switch_state(dev, XenbusStateClosing);
+}
+EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
+
+/**
+ * xenbus_grant_ring
+ * @dev: xenbus device
+ * @ring_mfn: mfn of ring to grant
+
+ * Grant access to the given @ring_mfn to the peer of the given device.  Return
+ * 0 on success, or -errno on error.  On error, the device will switch to
+ * XenbusStateClosing, and the error will be saved in the store.
+ */
+int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn)
+{
+       int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0);
+       if (err < 0)
+               xenbus_dev_fatal(dev, err, "granting access to ring page");
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_grant_ring);
+
+
+/**
+ * Allocate an event channel for the given xenbus_device, assigning the newly
+ * created local port to *port.  Return 0 on success, or -errno on error.  On
+ * error, the device will switch to XenbusStateClosing, and the error will be
+ * saved in the store.
+ */
+int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
+{
+       struct evtchn_alloc_unbound alloc_unbound;
+       int err;
+
+       alloc_unbound.dom = DOMID_SELF;
+       alloc_unbound.remote_dom = dev->otherend_id;
+
+       err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
+                                         &alloc_unbound);
+       if (err)
+               xenbus_dev_fatal(dev, err, "allocating event channel");
+       else
+               *port = alloc_unbound.port;
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
+
+
+/**
+ * Bind to an existing interdomain event channel in another domain. Returns 0
+ * on success and stores the local port in *port. On error, returns -errno,
+ * switches the device to XenbusStateClosing, and saves the error in XenStore.
+ */
+int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port)
+{
+       struct evtchn_bind_interdomain bind_interdomain;
+       int err;
+
+       bind_interdomain.remote_dom = dev->otherend_id;
+       bind_interdomain.remote_port = remote_port;
+
+       err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
+                                         &bind_interdomain);
+       if (err)
+               xenbus_dev_fatal(dev, err,
+                                "binding to event channel %d from domain %d",
+                                remote_port, dev->otherend_id);
+       else
+               *port = bind_interdomain.local_port;
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_bind_evtchn);
+
+
+/**
+ * Free an existing event channel. Returns 0 on success or -errno on error.
+ */
+int xenbus_free_evtchn(struct xenbus_device *dev, int port)
+{
+       struct evtchn_close close;
+       int err;
+
+       close.port = port;
+
+       err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
+       if (err)
+               xenbus_dev_error(dev, err, "freeing event channel %d", port);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
+
+
+/**
+ * xenbus_map_ring_valloc
+ * @dev: xenbus device
+ * @gnt_ref: grant reference
+ * @vaddr: pointer to address to be filled out by mapping
+ *
+ * Based on Rusty Russell's skeleton driver's map_page.
+ * Map a page of memory into this domain from another domain's grant table.
+ * xenbus_map_ring_valloc allocates a page of virtual address space, maps the
+ * page to that address, and sets *vaddr to that address.
+ * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
+ * or -ENOMEM on error. If an error is returned, device will switch to
+ * XenbusStateClosing and the error message will be saved in XenStore.
+ */
+int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void 
**vaddr)
+{
+       struct gnttab_map_grant_ref op = {
+               .flags = GNTMAP_host_map,
+               .ref   = gnt_ref,
+               .dom   = dev->otherend_id,
+       };
+       struct vm_struct *area;
+
+       *vaddr = NULL;
+
+       area = alloc_vm_area(PAGE_SIZE);
+       if (!area)
+               return -ENOMEM;
+
+       op.host_addr = (unsigned long)area->addr;
+
+       if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+               BUG();
+
+       if (op.status != GNTST_okay) {
+               free_vm_area(area);
+               xenbus_dev_fatal(dev, op.status,
+                                "mapping in shared page %d from domain %d",
+                                gnt_ref, dev->otherend_id);
+               return op.status;
+       }
+
+       /* Stuff the handle in an unused field */
+       area->phys_addr = (unsigned long)op.handle;
+
+       *vaddr = area->addr;
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
+
+
+/**
+ * xenbus_map_ring
+ * @dev: xenbus device
+ * @gnt_ref: grant reference
+ * @handle: pointer to grant handle to be filled
+ * @vaddr: address to be mapped to
+ *
+ * Map a page of memory into this domain from another domain's grant table.
+ * xenbus_map_ring does not allocate the virtual address space (you must do
+ * this yourself!). It only maps in the page to the specified address.
+ * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
+ * or -ENOMEM on error. If an error is returned, device will switch to
+ * XenbusStateClosing and the error message will be saved in XenStore.
+ */
+int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
+                   grant_handle_t *handle, void *vaddr)
+{
+       struct gnttab_map_grant_ref op = {
+               .host_addr = (unsigned long)vaddr,
+               .flags     = GNTMAP_host_map,
+               .ref       = gnt_ref,
+               .dom       = dev->otherend_id,
+       };
+
+       if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
+               BUG();
+
+       if (op.status != GNTST_okay) {
+               xenbus_dev_fatal(dev, op.status,
+                                "mapping in shared page %d from domain %d",
+                                gnt_ref, dev->otherend_id);
+       } else
+               *handle = op.handle;
+
+       return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_map_ring);
+
+
+/**
+ * xenbus_unmap_ring_vfree
+ * @dev: xenbus device
+ * @vaddr: addr to unmap
+ *
+ * Based on Rusty Russell's skeleton driver's unmap_page.
+ * Unmap a page of memory in this domain that was imported from another domain.
+ * Use xenbus_unmap_ring_vfree if you mapped in your memory with
+ * xenbus_map_ring_valloc (it will free the virtual address space).
+ * Returns 0 on success and returns GNTST_* on error
+ * (see xen/include/interface/grant_table.h).
+ */
+int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
+{
+       struct vm_struct *area;
+       struct gnttab_unmap_grant_ref op = {
+               .host_addr = (unsigned long)vaddr,
+       };
+
+       /* It'd be nice if linux/vmalloc.h provided a find_vm_area(void *addr)
+        * method so that we don't have to muck with vmalloc internals here.
+        * We could force the user to hang on to their struct vm_struct from
+        * xenbus_map_ring_valloc, but these 6 lines considerably simplify
+        * this API.
+        */
+       read_lock(&vmlist_lock);
+       for (area = vmlist; area != NULL; area = area->next) {
+               if (area->addr == vaddr)
+                       break;
+       }
+       read_unlock(&vmlist_lock);
+
+       if (!area) {
+               xenbus_dev_error(dev, -ENOENT,
+                                "can't find mapped virtual address %p", vaddr);
+               return GNTST_bad_virt_addr;
+       }
+
+       op.handle = (grant_handle_t)area->phys_addr;
+
+       if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+               BUG();
+
+       if (op.status == GNTST_okay)
+               free_vm_area(area);
+       else
+               xenbus_dev_error(dev, op.status,
+                                "unmapping page at handle %d error %d",
+                                (int16_t)area->phys_addr, op.status);
+
+       return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
+
+
+/**
+ * xenbus_unmap_ring
+ * @dev: xenbus device
+ * @handle: grant handle
+ * @vaddr: addr to unmap
+ *
+ * Unmap a page of memory in this domain that was imported from another domain.
+ * Returns 0 on success and returns GNTST_* on error
+ * (see xen/include/interface/grant_table.h).
+ */
+int xenbus_unmap_ring(struct xenbus_device *dev,
+                     grant_handle_t handle, void *vaddr)
+{
+       struct gnttab_unmap_grant_ref op = {
+               .host_addr = (unsigned long)vaddr,
+               .handle    = handle,
+       };
+
+       if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
+               BUG();
+
+       if (op.status != GNTST_okay)
+               xenbus_dev_error(dev, op.status,
+                                "unmapping page at handle %d error %d",
+                                handle, op.status);
+
+       return op.status;
+}
+EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
+
+
+/**
+ * xenbus_read_driver_state
+ * @path: path for driver
+ *
+ * Return the state of the driver rooted at the given store path, or
+ * XenbusStateUnknown if no state can be read.
+ */
+enum xenbus_state xenbus_read_driver_state(const char *path)
+{
+       enum xenbus_state result;
+       int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
+       if (err)
+               result = XenbusStateUnknown;
+
+       return result;
+}
+EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -0,0 +1,218 @@
+/******************************************************************************
+ * xenbus_comms.c
+ *
+ * Low level code to talks to Xen Store: ringbuffer and event channel.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/wait.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <xen/xenbus.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/events.h>
+#include <xen/page.h>
+#include "xenbus_comms.h"
+
+static int xenbus_irq;
+
+static DECLARE_WORK(probe_work, xenbus_probe);
+
+static DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
+
+static irqreturn_t wake_waiting(int irq, void *unused)
+{
+       if (unlikely(xenstored_ready == 0)) {
+               xenstored_ready = 1;
+               schedule_work(&probe_work);
+       }
+
+       wake_up(&xb_waitq);
+       return IRQ_HANDLED;
+}
+
+static int check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
+{
+       return ((prod - cons) <= XENSTORE_RING_SIZE);
+}
+
+static void *get_output_chunk(XENSTORE_RING_IDX cons,
+                             XENSTORE_RING_IDX prod,
+                             char *buf, uint32_t *len)
+{
+       *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod);
+       if ((XENSTORE_RING_SIZE - (prod - cons)) < *len)
+               *len = XENSTORE_RING_SIZE - (prod - cons);
+       return buf + MASK_XENSTORE_IDX(prod);
+}
+
+static const void *get_input_chunk(XENSTORE_RING_IDX cons,
+                                  XENSTORE_RING_IDX prod,
+                                  const char *buf, uint32_t *len)
+{
+       *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons);
+       if ((prod - cons) < *len)
+               *len = prod - cons;
+       return buf + MASK_XENSTORE_IDX(cons);
+}
+
+/**
+ * xb_write - low level write
+ * @data: buffer to send
+ * @len: length of buffer
+ *
+ * Returns 0 on success, error otherwise.
+ */
+int xb_write(const void *data, unsigned len)
+{
+       struct xenstore_domain_interface *intf = xen_store_interface;
+       XENSTORE_RING_IDX cons, prod;
+       int rc;
+
+       while (len != 0) {
+               void *dst;
+               unsigned int avail;
+
+               rc = wait_event_interruptible(
+                       xb_waitq,
+                       (intf->req_prod - intf->req_cons) !=
+                       XENSTORE_RING_SIZE);
+               if (rc < 0)
+                       return rc;
+
+               /* Read indexes, then verify. */
+               cons = intf->req_cons;
+               prod = intf->req_prod;
+               mb();
+               if (!check_indexes(cons, prod)) {
+                       intf->req_cons = intf->req_prod = 0;
+                       return -EIO;
+               }
+
+               dst = get_output_chunk(cons, prod, intf->req, &avail);
+               if (avail == 0)
+                       continue;
+               if (avail > len)
+                       avail = len;
+
+               memcpy(dst, data, avail);
+               data += avail;
+               len -= avail;
+
+               /* Other side must not see new header until data is there. */
+               wmb();
+               intf->req_prod += avail;
+
+               /* This implies mb() before other side sees interrupt. */
+               notify_remote_via_evtchn(xen_store_evtchn);
+       }
+
+       return 0;
+}
+
+/**
+ * xb_read - low level read
+ * @data: buffer to fill
+ * @len: length of buffer
+ *
+ * Returns 0 on success, error otherwise.
+ */
+int xb_read(void *data, unsigned len)
+{
+       struct xenstore_domain_interface *intf = xen_store_interface;
+       XENSTORE_RING_IDX cons, prod;
+       int rc;
+
+       while (len != 0) {
+               unsigned int avail;
+               const char *src;
+
+               rc = wait_event_interruptible(
+                       xb_waitq,
+                       intf->rsp_cons != intf->rsp_prod);
+               if (rc < 0)
+                       return rc;
+
+               /* Read indexes, then verify. */
+               cons = intf->rsp_cons;
+               prod = intf->rsp_prod;
+               mb();
+               if (!check_indexes(cons, prod)) {
+                       intf->rsp_cons = intf->rsp_prod = 0;
+                       return -EIO;
+               }
+
+               src = get_input_chunk(cons, prod, intf->rsp, &avail);
+               if (avail == 0)
+                       continue;
+               if (avail > len)
+                       avail = len;
+
+               /* We must read header before we read data. */
+               rmb();
+
+               memcpy(data, src, avail);
+               data += avail;
+               len -= avail;
+
+               /* Other side must not see free space until we've copied out */
+               mb();
+               intf->rsp_cons += avail;
+
+               pr_debug("Finished read of %i bytes (%i to go)\n", avail, len);
+
+               /* Implies mb(): they will see new header. */
+               notify_remote_via_evtchn(xen_store_evtchn);
+       }
+
+       return 0;
+}
+
+/**
+ * xb_init_comms - Set up interrupt handler off store event channel.
+ */
+int xb_init_comms(void)
+{
+       int err;
+
+       if (xenbus_irq)
+               unbind_from_irqhandler(xenbus_irq, &xb_waitq);
+
+       err = bind_evtchn_to_irqhandler(
+               xen_store_evtchn, wake_waiting,
+               0, "xenbus", &xb_waitq);
+       if (err <= 0) {
+               printk(KERN_ERR "XENBUS request irq failed %i\n", err);
+               return err;
+       }
+
+       xenbus_irq = err;
+
+       return 0;
+}
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_comms.h
@@ -0,0 +1,44 @@
+/*
+ * Private include for xenbus communications.
+ * 
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _XENBUS_COMMS_H
+#define _XENBUS_COMMS_H
+
+int xs_init(void);
+int xb_init_comms(void);
+
+/* Low level routines. */
+int xb_write(const void *data, unsigned len);
+int xb_read(void *data, unsigned len);
+int xs_input_avail(void);
+extern struct xenstore_domain_interface *xen_store_interface;
+extern int xen_store_evtchn;
+
+#endif /* _XENBUS_COMMS_H */
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -0,0 +1,891 @@
+/******************************************************************************
+ * Talks to Xen Store to figure out what devices we have.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 Mike Wray, Hewlett-Packard
+ * Copyright (C) 2005, 2006 XenSource Ltd
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define DPRINTK(fmt, args...)                          \
+       pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
+                __FUNCTION__, __LINE__, ##args)
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+#include <linux/mutex.h>
+
+#include <asm/io.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/xenbus.h>
+#include <xen/events.h>
+#include <xen/page.h>
+
+#include "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+int xen_store_evtchn;
+struct xenstore_domain_interface *xen_store_interface;
+static unsigned long xen_store_mfn;
+
+static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
+
+static void wait_for_devices(struct xenbus_driver *xendrv);
+
+static int xenbus_probe_frontend(const char *type, const char *name);
+
+static void xenbus_dev_shutdown(struct device *_dev);
+
+/* If something in array of ids matches this device, return it. */
+static const struct xenbus_device_id *
+match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
+{
+       for (; *arr->devicetype != '\0'; arr++) {
+               if (!strcmp(arr->devicetype, dev->devicetype))
+                       return arr;
+       }
+       return NULL;
+}
+
+int xenbus_match(struct device *_dev, struct device_driver *_drv)
+{
+       struct xenbus_driver *drv = to_xenbus_driver(_drv);
+
+       if (!drv->ids)
+               return 0;
+
+       return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
+}
+
+/* device/<type>/<id> => <type>-<id> */
+static int frontend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
+{
+       nodename = strchr(nodename, '/');
+       if (!nodename || strlen(nodename + 1) >= BUS_ID_SIZE) {
+               printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
+               return -EINVAL;
+       }
+
+       strlcpy(bus_id, nodename + 1, BUS_ID_SIZE);
+       if (!strchr(bus_id, '/')) {
+               printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
+               return -EINVAL;
+       }
+       *strchr(bus_id, '/') = '-';
+       return 0;
+}
+
+
+static void free_otherend_details(struct xenbus_device *dev)
+{
+       kfree(dev->otherend);
+       dev->otherend = NULL;
+}
+
+
+static void free_otherend_watch(struct xenbus_device *dev)
+{
+       if (dev->otherend_watch.node) {
+               unregister_xenbus_watch(&dev->otherend_watch);
+               kfree(dev->otherend_watch.node);
+               dev->otherend_watch.node = NULL;
+       }
+}
+
+
+int read_otherend_details(struct xenbus_device *xendev,
+                                char *id_node, char *path_node)
+{
+       int err = xenbus_gather(XBT_NIL, xendev->nodename,
+                               id_node, "%i", &xendev->otherend_id,
+                               path_node, NULL, &xendev->otherend,
+                               NULL);
+       if (err) {
+               xenbus_dev_fatal(xendev, err,
+                                "reading other end details from %s",
+                                xendev->nodename);
+               return err;
+       }
+       if (strlen(xendev->otherend) == 0 ||
+           !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
+               xenbus_dev_fatal(xendev, -ENOENT,
+                                "unable to read other end from %s.  "
+                                "missing or inaccessible.",
+                                xendev->nodename);
+               free_otherend_details(xendev);
+               return -ENOENT;
+       }
+
+       return 0;
+}
+
+
+static int read_backend_details(struct xenbus_device *xendev)
+{
+       return read_otherend_details(xendev, "backend-id", "backend");
+}
+
+
+/* Bus type for frontend drivers. */
+static struct xen_bus_type xenbus_frontend = {
+       .root = "device",
+       .levels = 2,            /* device/type/<id> */
+       .get_bus_id = frontend_bus_id,
+       .probe = xenbus_probe_frontend,
+       .bus = {
+               .name     = "xen",
+               .match    = xenbus_match,
+               .probe    = xenbus_dev_probe,
+               .remove   = xenbus_dev_remove,
+               .shutdown = xenbus_dev_shutdown,
+       },
+};
+
+static void otherend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+       struct xenbus_device *dev =
+               container_of(watch, struct xenbus_device, otherend_watch);
+       struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
+       enum xenbus_state state;
+
+       /* Protect us against watches firing on old details when the otherend
+          details change, say immediately after a resume. */
+       if (!dev->otherend ||
+           strncmp(dev->otherend, vec[XS_WATCH_PATH],
+                   strlen(dev->otherend))) {
+               dev_dbg(&dev->dev, "Ignoring watch at %s", vec[XS_WATCH_PATH]);
+               return;
+       }
+
+       state = xenbus_read_driver_state(dev->otherend);
+
+       dev_dbg(&dev->dev, "state is %d, (%s), %s, %s",
+               state, xenbus_strstate(state), dev->otherend_watch.node,
+               vec[XS_WATCH_PATH]);
+
+       /*
+        * Ignore xenbus transitions during shutdown. This prevents us doing
+        * work that can fail e.g., when the rootfs is gone.
+        */
+       if (system_state > SYSTEM_RUNNING) {
+               struct xen_bus_type *bus = bus;
+               bus = container_of(dev->dev.bus, struct xen_bus_type, bus);
+               /* If we're frontend, drive the state machine to Closed. */
+               /* This should cause the backend to release our resources. */
+               if ((bus == &xenbus_frontend) && (state == XenbusStateClosing))
+                       xenbus_frontend_closed(dev);
+               return;
+       }
+
+       if (drv->otherend_changed)
+               drv->otherend_changed(dev, state);
+}
+
+
+static int talk_to_otherend(struct xenbus_device *dev)
+{
+       struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
+
+       free_otherend_watch(dev);
+       free_otherend_details(dev);
+
+       return drv->read_otherend_details(dev);
+}
+
+
+static int watch_otherend(struct xenbus_device *dev)
+{
+       return xenbus_watch_path2(dev, dev->otherend, "state",
+                                 &dev->otherend_watch, otherend_changed);
+}
+
+
+int xenbus_dev_probe(struct device *_dev)
+{
+       struct xenbus_device *dev = to_xenbus_device(_dev);
+       struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+       const struct xenbus_device_id *id;
+       int err;
+
+       DPRINTK("%s", dev->nodename);
+
+       if (!drv->probe) {
+               err = -ENODEV;
+               goto fail;
+       }
+
+       id = match_device(drv->ids, dev);
+       if (!id) {
+               err = -ENODEV;
+               goto fail;
+       }
+
+       err = talk_to_otherend(dev);
+       if (err) {
+               dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
+                        dev->nodename);
+               return err;
+       }
+
+       err = drv->probe(dev, id);
+       if (err)
+               goto fail;
+
+       err = watch_otherend(dev);
+       if (err) {
+               dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
+                      dev->nodename);
+               return err;
+       }
+
+       return 0;
+fail:
+       xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
+       xenbus_switch_state(dev, XenbusStateClosed);
+       return -ENODEV;
+}
+
+int xenbus_dev_remove(struct device *_dev)
+{
+       struct xenbus_device *dev = to_xenbus_device(_dev);
+       struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+
+       DPRINTK("%s", dev->nodename);
+
+       free_otherend_watch(dev);
+       free_otherend_details(dev);
+
+       if (drv->remove)
+               drv->remove(dev);
+
+       xenbus_switch_state(dev, XenbusStateClosed);
+       return 0;
+}
+
+static void xenbus_dev_shutdown(struct device *_dev)
+{
+       struct xenbus_device *dev = to_xenbus_device(_dev);
+       unsigned long timeout = 5*HZ;
+
+       DPRINTK("%s", dev->nodename);
+
+       get_device(&dev->dev);
+       if (dev->state != XenbusStateConnected) {
+               printk("%s: %s: %s != Connected, skipping\n", __FUNCTION__,
+                      dev->nodename, xenbus_strstate(dev->state));
+               goto out;
+       }
+       xenbus_switch_state(dev, XenbusStateClosing);
+       timeout = wait_for_completion_timeout(&dev->down, timeout);
+       if (!timeout)
+               printk("%s: %s timeout closing device\n", __FUNCTION__, 
dev->nodename);
+ out:
+       put_device(&dev->dev);
+}
+
+int xenbus_register_driver_common(struct xenbus_driver *drv,
+                                 struct xen_bus_type *bus)
+{
+       drv->driver.name = drv->name;
+       drv->driver.bus = &bus->bus;
+       drv->driver.owner = drv->owner;
+
+       return driver_register(&drv->driver);
+}
+
+int xenbus_register_frontend(struct xenbus_driver *drv)
+{
+       int ret;
+
+       drv->read_otherend_details = read_backend_details;
+
+       ret = xenbus_register_driver_common(drv, &xenbus_frontend);
+       if (ret)
+               return ret;
+
+       /* If this driver is loaded as a module wait for devices to attach. */
+       wait_for_devices(drv);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_register_frontend);
+
+void xenbus_unregister_driver(struct xenbus_driver *drv)
+{
+       driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
+
+struct xb_find_info
+{
+       struct xenbus_device *dev;
+       const char *nodename;
+};
+
+static int cmp_dev(struct device *dev, void *data)
+{
+       struct xenbus_device *xendev = to_xenbus_device(dev);
+       struct xb_find_info *info = data;
+
+       if (!strcmp(xendev->nodename, info->nodename)) {
+               info->dev = xendev;
+               get_device(dev);
+               return 1;
+       }
+       return 0;
+}
+
+struct xenbus_device *xenbus_device_find(const char *nodename,
+                                        struct bus_type *bus)
+{
+       struct xb_find_info info = { .dev = NULL, .nodename = nodename };
+
+       bus_for_each_dev(bus, NULL, &info, cmp_dev);
+       return info.dev;
+}
+
+static int cleanup_dev(struct device *dev, void *data)
+{
+       struct xenbus_device *xendev = to_xenbus_device(dev);
+       struct xb_find_info *info = data;
+       int len = strlen(info->nodename);
+
+       DPRINTK("%s", info->nodename);
+
+       /* Match the info->nodename path, or any subdirectory of that path. */
+       if (strncmp(xendev->nodename, info->nodename, len))
+               return 0;
+
+       /* If the node name is longer, ensure it really is a subdirectory. */
+       if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
+               return 0;
+
+       info->dev = xendev;
+       get_device(dev);
+       return 1;
+}
+
+static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
+{
+       struct xb_find_info info = { .nodename = path };
+
+       do {
+               info.dev = NULL;
+               bus_for_each_dev(bus, NULL, &info, cleanup_dev);
+               if (info.dev) {
+                       device_unregister(&info.dev->dev);
+                       put_device(&info.dev->dev);
+               }
+       } while (info.dev);
+}
+
+static void xenbus_dev_release(struct device *dev)
+{
+       if (dev)
+               kfree(to_xenbus_device(dev));
+}
+
+static ssize_t xendev_show_nodename(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+       return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
+}
+DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);
+
+static ssize_t xendev_show_devtype(struct device *dev,
+                                  struct device_attribute *attr, char *buf)
+{
+       return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
+}
+DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);
+
+
+int xenbus_probe_node(struct xen_bus_type *bus,
+                     const char *type,
+                     const char *nodename)
+{
+       int err;
+       struct xenbus_device *xendev;
+       size_t stringlen;
+       char *tmpstring;
+
+       enum xenbus_state state = xenbus_read_driver_state(nodename);
+
+       if (state != XenbusStateInitialising) {
+               /* Device is not new, so ignore it.  This can happen if a
+                  device is going away after switching to Closed.  */
+               return 0;
+       }
+
+       stringlen = strlen(nodename) + 1 + strlen(type) + 1;
+       xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
+       if (!xendev)
+               return -ENOMEM;
+
+       xendev->state = XenbusStateInitialising;
+
+       /* Copy the strings into the extra space. */
+
+       tmpstring = (char *)(xendev + 1);
+       strcpy(tmpstring, nodename);
+       xendev->nodename = tmpstring;
+
+       tmpstring += strlen(tmpstring) + 1;
+       strcpy(tmpstring, type);
+       xendev->devicetype = tmpstring;
+       init_completion(&xendev->down);
+
+       xendev->dev.bus = &bus->bus;
+       xendev->dev.release = xenbus_dev_release;
+
+       err = bus->get_bus_id(xendev->dev.bus_id, xendev->nodename);
+       if (err)
+               goto fail;
+
+       /* Register with generic device framework. */
+       err = device_register(&xendev->dev);
+       if (err)
+               goto fail;
+
+       device_create_file(&xendev->dev, &dev_attr_nodename);
+       device_create_file(&xendev->dev, &dev_attr_devtype);
+
+       return 0;
+fail:
+       kfree(xendev);
+       return err;
+}
+
+/* device/<typename>/<name> */
+static int xenbus_probe_frontend(const char *type, const char *name)
+{
+       char *nodename;
+       int err;
+
+       nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", xenbus_frontend.root, 
type, name);
+       if (!nodename)
+               return -ENOMEM;
+
+       DPRINTK("%s", nodename);
+
+       err = xenbus_probe_node(&xenbus_frontend, type, nodename);
+       kfree(nodename);
+       return err;
+}
+
+static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
+{
+       int err = 0;
+       char **dir;
+       unsigned int dir_n = 0;
+       int i;
+
+       dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
+       if (IS_ERR(dir))
+               return PTR_ERR(dir);
+
+       for (i = 0; i < dir_n; i++) {
+               err = bus->probe(type, dir[i]);
+               if (err)
+                       break;
+       }
+       kfree(dir);
+       return err;
+}
+
+int xenbus_probe_devices(struct xen_bus_type *bus)
+{
+       int err = 0;
+       char **dir;
+       unsigned int i, dir_n;
+
+       dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
+       if (IS_ERR(dir))
+               return PTR_ERR(dir);
+
+       for (i = 0; i < dir_n; i++) {
+               err = xenbus_probe_device_type(bus, dir[i]);
+               if (err)
+                       break;
+       }
+       kfree(dir);
+       return err;
+}
+
+static unsigned int char_count(const char *str, char c)
+{
+       unsigned int i, ret = 0;
+
+       for (i = 0; str[i]; i++)
+               if (str[i] == c)
+                       ret++;
+       return ret;
+}
+
+static int strsep_len(const char *str, char c, unsigned int len)
+{
+       unsigned int i;
+
+       for (i = 0; str[i]; i++)
+               if (str[i] == c) {
+                       if (len == 0)
+                               return i;
+                       len--;
+               }
+       return (len == 0) ? i : -ERANGE;
+}
+
+void dev_changed(const char *node, struct xen_bus_type *bus)
+{
+       int exists, rootlen;
+       struct xenbus_device *dev;
+       char type[BUS_ID_SIZE];
+       const char *p, *root;
+
+       if (char_count(node, '/') < 2)
+               return;
+
+       exists = xenbus_exists(XBT_NIL, node, "");
+       if (!exists) {
+               xenbus_cleanup_devices(node, &bus->bus);
+               return;
+       }
+
+       /* backend/<type>/... or device/<type>/... */
+       p = strchr(node, '/') + 1;
+       snprintf(type, BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
+       type[BUS_ID_SIZE-1] = '\0';
+
+       rootlen = strsep_len(node, '/', bus->levels);
+       if (rootlen < 0)
+               return;
+       root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
+       if (!root)
+               return;
+
+       dev = xenbus_device_find(root, &bus->bus);
+       if (!dev)
+               xenbus_probe_node(bus, type, root);
+       else
+               put_device(&dev->dev);
+
+       kfree(root);
+}
+
+static void frontend_changed(struct xenbus_watch *watch,
+                            const char **vec, unsigned int len)
+{
+       DPRINTK("");
+
+       dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
+}
+
+/* We watch for devices appearing and vanishing. */
+static struct xenbus_watch fe_watch = {
+       .node = "device",
+       .callback = frontend_changed,
+};
+
+static int suspend_dev(struct device *dev, void *data)
+{
+       int err = 0;
+       struct xenbus_driver *drv;
+       struct xenbus_device *xdev;
+
+       DPRINTK("");
+
+       if (dev->driver == NULL)
+               return 0;
+       drv = to_xenbus_driver(dev->driver);
+       xdev = container_of(dev, struct xenbus_device, dev);
+       if (drv->suspend)
+               err = drv->suspend(xdev);
+       if (err)
+               printk(KERN_WARNING
+                      "xenbus: suspend %s failed: %i\n", dev->bus_id, err);
+       return 0;
+}
+
+static int resume_dev(struct device *dev, void *data)
+{
+       int err;
+       struct xenbus_driver *drv;
+       struct xenbus_device *xdev;
+
+       DPRINTK("");
+
+       if (dev->driver == NULL)
+               return 0;
+
+       drv = to_xenbus_driver(dev->driver);
+       xdev = container_of(dev, struct xenbus_device, dev);
+
+       err = talk_to_otherend(xdev);
+       if (err) {
+               printk(KERN_WARNING
+                      "xenbus: resume (talk_to_otherend) %s failed: %i\n",
+                      dev->bus_id, err);
+               return err;
+       }
+
+       xdev->state = XenbusStateInitialising;
+
+       if (drv->resume) {
+               err = drv->resume(xdev);
+               if (err) { 
+                       printk(KERN_WARNING
+                              "xenbus: resume %s failed: %i\n", 
+                              dev->bus_id, err);
+                       return err;
+               }
+       }
+
+       err = watch_otherend(xdev);
+       if (err) {
+               printk(KERN_WARNING
+                      "xenbus_probe: resume (watch_otherend) %s failed: "
+                      "%d.\n", dev->bus_id, err);
+               return err;
+       }
+
+       return 0;
+}
+
+void xenbus_suspend(void)
+{
+       DPRINTK("");
+
+       bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_dev);
+       xenbus_backend_suspend(suspend_dev);
+       xs_suspend();
+}
+EXPORT_SYMBOL_GPL(xenbus_suspend);
+
+void xenbus_resume(void)
+{
+       xb_init_comms();
+       xs_resume();
+       bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, resume_dev);
+       xenbus_backend_resume(resume_dev);
+}
+EXPORT_SYMBOL_GPL(xenbus_resume);
+
+
+/* A flag to determine if xenstored is 'ready' (i.e. has started) */
+int xenstored_ready = 0;
+
+
+int register_xenstore_notifier(struct notifier_block *nb)
+{
+       int ret = 0;
+
+       if (xenstored_ready > 0)
+               ret = nb->notifier_call(nb, 0, NULL);
+       else
+               blocking_notifier_chain_register(&xenstore_chain, nb);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(register_xenstore_notifier);
+
+void unregister_xenstore_notifier(struct notifier_block *nb)
+{
+       blocking_notifier_chain_unregister(&xenstore_chain, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
+
+void xenbus_probe(struct work_struct *unused)
+{
+       BUG_ON((xenstored_ready <= 0));
+
+       /* Enumerate devices in xenstore and watch for changes. */
+       xenbus_probe_devices(&xenbus_frontend);
+       register_xenbus_watch(&fe_watch);
+       xenbus_backend_probe_and_watch();
+
+       /* Notify others that xenstore is up */
+       blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
+}
+
+static int __init xenbus_probe_init(void)
+{
+       int err = 0;
+
+       DPRINTK("");
+
+       err = -ENODEV;
+       if (!is_running_on_xen())
+               goto out_error;
+
+       /* Register ourselves with the kernel bus subsystem */
+       err = bus_register(&xenbus_frontend.bus);
+       if (err)
+               goto out_error;
+
+       err = xenbus_backend_bus_register();
+       if (err)
+               goto out_unreg_front;
+
+       /*
+        * Domain0 doesn't have a store_evtchn or store_mfn yet.
+        */
+       if (is_initial_xendomain()) {
+               /* dom0 not yet supported */
+       } else {
+               xenstored_ready = 1;
+               xen_store_evtchn = xen_start_info->store_evtchn;
+               xen_store_mfn = xen_start_info->store_mfn;
+       }
+       xen_store_interface = mfn_to_virt(xen_store_mfn);
+
+       /* Initialize the interface to xenstore. */
+       err = xs_init();
+       if (err) {
+               printk(KERN_WARNING
+                      "XENBUS: Error initializing xenstore comms: %i\n", err);
+               goto out_unreg_back;
+       }
+
+       if (!is_initial_xendomain())
+               xenbus_probe(NULL);
+
+       return 0;
+
+  out_unreg_back:
+       xenbus_backend_bus_unregister();
+
+  out_unreg_front:
+       bus_unregister(&xenbus_frontend.bus);
+
+  out_error:
+       return err;
+}
+
+postcore_initcall(xenbus_probe_init);
+
+MODULE_LICENSE("Dual BSD/GPL");
+
+static int is_disconnected_device(struct device *dev, void *data)
+{
+       struct xenbus_device *xendev = to_xenbus_device(dev);
+       struct device_driver *drv = data;
+
+       /*
+        * A device with no driver will never connect. We care only about
+        * devices which should currently be in the process of connecting.
+        */
+       if (!dev->driver)
+               return 0;
+
+       /* Is this search limited to a particular driver? */
+       if (drv && (dev->driver != drv))
+               return 0;
+
+       return (xendev->state != XenbusStateConnected);
+}
+
+static int exists_disconnected_device(struct device_driver *drv)
+{
+       return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+                               is_disconnected_device);
+}
+
+static int print_device_status(struct device *dev, void *data)
+{
+       struct xenbus_device *xendev = to_xenbus_device(dev);
+       struct device_driver *drv = data;
+
+       /* Is this operation limited to a particular driver? */
+       if (drv && (dev->driver != drv))
+               return 0;
+
+       if (!dev->driver) {
+               /* Information only: is this too noisy? */
+               printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
+                      xendev->nodename);
+       } else if (xendev->state != XenbusStateConnected) {
+               printk(KERN_WARNING "XENBUS: Timeout connecting "
+                      "to device: %s (state %d)\n",
+                      xendev->nodename, xendev->state);
+       }
+
+       return 0;
+}
+
+/* We only wait for device setup after most initcalls have run. */
+static int ready_to_wait_for_devices;
+
+/*
+ * On a 10 second timeout, wait for all devices currently configured.  We need
+ * to do this to guarantee that the filesystems and / or network devices
+ * needed for boot are available, before we can allow the boot to proceed.
+ *
+ * This needs to be on a late_initcall, to happen after the frontend device
+ * drivers have been initialised, but before the root fs is mounted.
+ *
+ * A possible improvement here would be to have the tools add a per-device
+ * flag to the store entry, indicating whether it is needed at boot time.
+ * This would allow people who knew what they were doing to accelerate their
+ * boot slightly, but of course needs tools or manual intervention to set up
+ * those flags correctly.
+ */
+static void wait_for_devices(struct xenbus_driver *xendrv)
+{
+       unsigned long timeout = jiffies + 10*HZ;
+       struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
+
+       if (!ready_to_wait_for_devices || !is_running_on_xen())
+               return;
+
+       while (exists_disconnected_device(drv)) {
+               if (time_after(jiffies, timeout))
+                       break;
+               schedule_timeout_interruptible(HZ/10);
+       }
+
+       bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
+                        print_device_status);
+}
+
+#ifndef MODULE
+static int __init boot_wait_for_devices(void)
+{
+       ready_to_wait_for_devices = 1;
+       wait_for_devices(NULL);
+       return 0;
+}
+
+late_initcall(boot_wait_for_devices);
+#endif
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe.h
@@ -0,0 +1,72 @@
+/******************************************************************************
+ * xenbus_probe.h
+ *
+ * Talks to Xen Store to figure out what devices we have.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 XenSource Ltd.
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _XENBUS_PROBE_H
+#define _XENBUS_PROBE_H
+
+#ifdef CONFIG_XEN_BACKEND
+extern void xenbus_backend_suspend(int (*fn)(struct device *, void *));
+extern void xenbus_backend_resume(int (*fn)(struct device *, void *));
+extern void xenbus_backend_probe_and_watch(void);
+extern int xenbus_backend_bus_register(void);
+extern void xenbus_backend_bus_unregister(void);
+#else
+static inline void xenbus_backend_suspend(int (*fn)(struct device *, void *)) 
{}
+static inline void xenbus_backend_resume(int (*fn)(struct device *, void *)) {}
+static inline void xenbus_backend_probe_and_watch(void) {}
+static inline int xenbus_backend_bus_register(void) {return 0;}
+static inline void xenbus_backend_bus_unregister(void) {}
+#endif
+
+struct xen_bus_type
+{
+       char *root;
+       unsigned int levels;
+       int (*get_bus_id)(char bus_id[BUS_ID_SIZE], const char *nodename);
+       int (*probe)(const char *type, const char *dir);
+       struct bus_type bus;
+};
+
+extern int xenbus_match(struct device *_dev, struct device_driver *_drv);
+extern int xenbus_dev_probe(struct device *_dev);
+extern int xenbus_dev_remove(struct device *_dev);
+extern int xenbus_register_driver_common(struct xenbus_driver *drv,
+                                        struct xen_bus_type *bus);
+extern int xenbus_probe_node(struct xen_bus_type *bus,
+                            const char *type,
+                            const char *nodename);
+extern int xenbus_probe_devices(struct xen_bus_type *bus);
+
+extern void dev_changed(const char *node, struct xen_bus_type *bus);
+
+#endif
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_probe_backend.c
@@ -0,0 +1,269 @@
+/******************************************************************************
+ * Talks to Xen Store to figure out what devices we have (backend half).
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 Mike Wray, Hewlett-Packard
+ * Copyright (C) 2005, 2006 XenSource Ltd
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#define DPRINTK(fmt, args...)                          \
+       pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
+                __FUNCTION__, __LINE__, ##args)
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/fcntl.h>
+#include <linux/mm.h>
+#include <linux/notifier.h>
+#include <linux/kthread.h>
+
+#include <asm/io.h>
+#include <asm/page.h>
+//#include <asm/maddr.h>
+#include <asm/pgtable.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/xenbus.h>
+//#include <xen/xen_proc.h>
+//#include <xen/evtchn.h>
+#include <xen/features.h>
+//#include <xen/hvm.h>
+
+#include "xenbus_comms.h"
+#include "xenbus_probe.h"
+
+#ifdef HAVE_XEN_PLATFORM_COMPAT_H
+#include <xen/platform-compat.h>
+#endif
+
+static int xenbus_uevent_backend(struct device *dev, char **envp,
+                                int num_envp, char *buffer, int buffer_size);
+static int xenbus_probe_backend(const char *type, const char *domid);
+
+extern int read_otherend_details(struct xenbus_device *xendev,
+                                char *id_node, char *path_node);
+
+static int read_frontend_details(struct xenbus_device *xendev)
+{
+       return read_otherend_details(xendev, "frontend-id", "frontend");
+}
+
+/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
+static int backend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
+{
+       int domid, err;
+       const char *devid, *type, *frontend;
+       unsigned int typelen;
+
+       type = strchr(nodename, '/');
+       if (!type)
+               return -EINVAL;
+       type++;
+       typelen = strcspn(type, "/");
+       if (!typelen || type[typelen] != '/')
+               return -EINVAL;
+
+       devid = strrchr(nodename, '/') + 1;
+
+       err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
+                           "frontend", NULL, &frontend,
+                           NULL);
+       if (err)
+               return err;
+       if (strlen(frontend) == 0)
+               err = -ERANGE;
+       if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
+               err = -ENOENT;
+
+       kfree(frontend);
+
+       if (err)
+               return err;
+
+       if (snprintf(bus_id, BUS_ID_SIZE,
+                    "%.*s-%i-%s", typelen, type, domid, devid) >= BUS_ID_SIZE)
+               return -ENOSPC;
+       return 0;
+}
+
+static struct xen_bus_type xenbus_backend = {
+       .root = "backend",
+       .levels = 3,            /* backend/type/<frontend>/<id> */
+       .get_bus_id = backend_bus_id,
+       .probe = xenbus_probe_backend,
+       .bus = {
+               .name     = "xen-backend",
+               .match    = xenbus_match,
+               .probe    = xenbus_dev_probe,
+               .remove   = xenbus_dev_remove,
+//             .shutdown = xenbus_dev_shutdown,
+               .uevent   = xenbus_uevent_backend,
+       },
+};
+
+static int xenbus_uevent_backend(struct device *dev, char **envp,
+                                int num_envp, char *buffer, int buffer_size)
+{
+       struct xenbus_device *xdev;
+       struct xenbus_driver *drv;
+       int i = 0;
+       int length = 0;
+
+       DPRINTK("");
+
+       if (dev == NULL)
+               return -ENODEV;
+
+       xdev = to_xenbus_device(dev);
+       if (xdev == NULL)
+               return -ENODEV;
+
+       /* stuff we want to pass to /sbin/hotplug */
+       add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
+                      "XENBUS_TYPE=%s", xdev->devicetype);
+
+       add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
+                      "XENBUS_PATH=%s", xdev->nodename);
+
+       add_uevent_var(envp, num_envp, &i, buffer, buffer_size, &length,
+                      "XENBUS_BASE_PATH=%s", xenbus_backend.root);
+
+       /* terminate, set to next free slot, shrink available space */
+       envp[i] = NULL;
+       envp = &envp[i];
+       num_envp -= i;
+       buffer = &buffer[length];
+       buffer_size -= length;
+
+       if (dev->driver) {
+               drv = to_xenbus_driver(dev->driver);
+               if (drv && drv->uevent)
+                       return drv->uevent(xdev, envp, num_envp, buffer,
+                                          buffer_size);
+       }
+
+       return 0;
+}
+
+int xenbus_register_backend(struct xenbus_driver *drv)
+{
+       drv->read_otherend_details = read_frontend_details;
+
+       return xenbus_register_driver_common(drv, &xenbus_backend);
+}
+EXPORT_SYMBOL_GPL(xenbus_register_backend);
+
+/* backend/<typename>/<frontend-uuid>/<name> */
+static int xenbus_probe_backend_unit(const char *dir,
+                                    const char *type,
+                                    const char *name)
+{
+       char *nodename;
+       int err;
+
+       nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
+       if (!nodename)
+               return -ENOMEM;
+
+       DPRINTK("%s\n", nodename);
+
+       err = xenbus_probe_node(&xenbus_backend, type, nodename);
+       kfree(nodename);
+       return err;
+}
+
+/* backend/<typename>/<frontend-domid> */
+static int xenbus_probe_backend(const char *type, const char *domid)
+{
+       char *nodename;
+       int err = 0;
+       char **dir;
+       unsigned int i, dir_n = 0;
+
+       DPRINTK("");
+
+       nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", xenbus_backend.root, type, 
domid);
+       if (!nodename)
+               return -ENOMEM;
+
+       dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
+       if (IS_ERR(dir)) {
+               kfree(nodename);
+               return PTR_ERR(dir);
+       }
+
+       for (i = 0; i < dir_n; i++) {
+               err = xenbus_probe_backend_unit(nodename, type, dir[i]);
+               if (err)
+                       break;
+       }
+       kfree(dir);
+       kfree(nodename);
+       return err;
+}
+
+static void backend_changed(struct xenbus_watch *watch,
+                           const char **vec, unsigned int len)
+{
+       DPRINTK("");
+
+       dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
+}
+
+static struct xenbus_watch be_watch = {
+       .node = "backend",
+       .callback = backend_changed,
+};
+
+void xenbus_backend_suspend(int (*fn)(struct device *, void *))
+{
+       DPRINTK("");
+       bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
+}
+
+void xenbus_backend_resume(int (*fn)(struct device *, void *))
+{
+       DPRINTK("");
+       bus_for_each_dev(&xenbus_backend.bus, NULL, NULL, fn);
+}
+
+void xenbus_backend_probe_and_watch(void)
+{
+       xenbus_probe_devices(&xenbus_backend);
+       register_xenbus_watch(&be_watch);
+}
+
+int xenbus_backend_bus_register(void)
+{
+       return bus_register(&xenbus_backend.bus);
+}
+
+void xenbus_backend_bus_unregister(void)
+{
+       bus_unregister(&xenbus_backend.bus);
+}
===================================================================
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -0,0 +1,840 @@
+/******************************************************************************
+ * xenbus_xs.c
+ *
+ * This is the kernel equivalent of the "xs" library.  We don't need everything
+ * and we use xenbus_comms for communication.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/unistd.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/uio.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/fcntl.h>
+#include <linux/kthread.h>
+#include <linux/rwsem.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <xen/xenbus.h>
+#include "xenbus_comms.h"
+
+struct xs_stored_msg {
+       struct list_head list;
+
+       struct xsd_sockmsg hdr;
+
+       union {
+               /* Queued replies. */
+               struct {
+                       char *body;
+               } reply;
+
+               /* Queued watch events. */
+               struct {
+                       struct xenbus_watch *handle;
+                       char **vec;
+                       unsigned int vec_size;
+               } watch;
+       } u;
+};
+
+struct xs_handle {
+       /* A list of replies. Currently only one will ever be outstanding. */
+       struct list_head reply_list;
+       spinlock_t reply_lock;
+       wait_queue_head_t reply_waitq;
+
+       /* One request at a time. */
+       struct mutex request_mutex;
+
+       /* Protect transactions against save/restore. */
+       struct rw_semaphore suspend_mutex;
+};
+
+static struct xs_handle xs_state;
+
+/* List of registered watches, and a lock to protect it. */
+static LIST_HEAD(watches);
+static DEFINE_SPINLOCK(watches_lock);
+
+/* List of pending watch callback events, and a lock to protect it. */
+static LIST_HEAD(watch_events);
+static DEFINE_SPINLOCK(watch_events_lock);
+
+/*
+ * Details of the xenwatch callback kernel thread. The thread waits on the
+ * watch_events_waitq for work to do (queued on watch_events list). When it
+ * wakes up it acquires the xenwatch_mutex before reading the list and
+ * carrying out work.
+ */
+static pid_t xenwatch_pid;
+static DEFINE_MUTEX(xenwatch_mutex);
+static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq);
+
+static int get_error(const char *errorstring)
+{
+       unsigned int i;
+
+       for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) {
+               if (i == ARRAY_SIZE(xsd_errors) - 1) {
+                       printk(KERN_WARNING
+                              "XENBUS xen store gave: unknown error %s",
+                              errorstring);
+                       return EINVAL;
+               }
+       }
+       return xsd_errors[i].errnum;
+}
+
+static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
+{
+       struct xs_stored_msg *msg;
+       char *body;
+
+       spin_lock(&xs_state.reply_lock);
+
+       while (list_empty(&xs_state.reply_list)) {
+               spin_unlock(&xs_state.reply_lock);
+               /* XXX FIXME: Avoid synchronous wait for response here. */
+               wait_event(xs_state.reply_waitq,
+                          !list_empty(&xs_state.reply_list));
+               spin_lock(&xs_state.reply_lock);
+       }
+
+       msg = list_entry(xs_state.reply_list.next,
+                        struct xs_stored_msg, list);
+       list_del(&msg->list);
+
+       spin_unlock(&xs_state.reply_lock);
+
+       *type = msg->hdr.type;
+       if (len)
+               *len = msg->hdr.len;
+       body = msg->u.reply.body;
+
+       kfree(msg);
+
+       return body;
+}
+
+/* Emergency write. */
+void xenbus_debug_write(const char *str, unsigned int count)
+{
+       struct xsd_sockmsg msg = { 0 };
+
+       msg.type = XS_DEBUG;
+       msg.len = sizeof("print") + count + 1;
+
+       mutex_lock(&xs_state.request_mutex);
+       xb_write(&msg, sizeof(msg));
+       xb_write("print", sizeof("print"));
+       xb_write(str, count);
+       xb_write("", 1);
+       mutex_unlock(&xs_state.request_mutex);
+}
+
+void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
+{
+       void *ret;
+       struct xsd_sockmsg req_msg = *msg;
+       int err;
+
+       if (req_msg.type == XS_TRANSACTION_START)
+               down_read(&xs_state.suspend_mutex);
+
+       mutex_lock(&xs_state.request_mutex);
+
+       err = xb_write(msg, sizeof(*msg) + msg->len);
+       if (err) {
+               msg->type = XS_ERROR;
+               ret = ERR_PTR(err);
+       } else
+               ret = read_reply(&msg->type, &msg->len);
+
+       mutex_unlock(&xs_state.request_mutex);
+
+       if ((msg->type == XS_TRANSACTION_END) ||
+           ((req_msg.type == XS_TRANSACTION_START) &&
+            (msg->type == XS_ERROR)))
+               up_read(&xs_state.suspend_mutex);
+
+       return ret;
+}
+
+/* Send message to xs, get kmalloc'ed reply.  ERR_PTR() on error. */
+static void *xs_talkv(struct xenbus_transaction t,
+                     enum xsd_sockmsg_type type,
+                     const struct kvec *iovec,
+                     unsigned int num_vecs,
+                     unsigned int *len)
+{
+       struct xsd_sockmsg msg;
+       void *ret = NULL;
+       unsigned int i;
+       int err;
+
+       msg.tx_id = t.id;
+       msg.req_id = 0;
+       msg.type = type;
+       msg.len = 0;
+       for (i = 0; i < num_vecs; i++)
+               msg.len += iovec[i].iov_len;
+
+       mutex_lock(&xs_state.request_mutex);
+
+       err = xb_write(&msg, sizeof(msg));
+       if (err) {
+               mutex_unlock(&xs_state.request_mutex);
+               return ERR_PTR(err);
+       }
+
+       for (i = 0; i < num_vecs; i++) {
+               err = xb_write(iovec[i].iov_base, iovec[i].iov_len);;
+               if (err) {
+                       mutex_unlock(&xs_state.request_mutex);
+                       return ERR_PTR(err);
+               }
+       }
+
+       ret = read_reply(&msg.type, len);
+
+       mutex_unlock(&xs_state.request_mutex);
+
+       if (IS_ERR(ret))
+               return ret;
+
+       if (msg.type == XS_ERROR) {
+               err = get_error(ret);
+               kfree(ret);
+               return ERR_PTR(-err);
+       }
+
+       if (msg.type != type) {
+               if (printk_ratelimit())
+                       printk(KERN_WARNING
+                              "XENBUS unexpected type [%d], expected [%d]\n",
+                              msg.type, type);
+               kfree(ret);
+               return ERR_PTR(-EINVAL);
+       }
+       return ret;
+}
+
+/* Simplified version of xs_talkv: single message. */
+static void *xs_single(struct xenbus_transaction t,
+                      enum xsd_sockmsg_type type,
+                      const char *string,
+                      unsigned int *len)
+{
+       struct kvec iovec;
+
+       iovec.iov_base = (void *)string;
+       iovec.iov_len = strlen(string) + 1;
+       return xs_talkv(t, type, &iovec, 1, len);
+}
+
+/* Many commands only need an ack, don't care what it says. */
+static int xs_error(char *reply)
+{
+       if (IS_ERR(reply))
+               return PTR_ERR(reply);
+       kfree(reply);
+       return 0;
+}
+
+static unsigned int count_strings(const char *strings, unsigned int len)
+{
+       unsigned int num;
+       const char *p;
+
+       for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1)
+               num++;
+
+       return num;
+}
+
+/* Return the path to dir with /name appended. Buffer must be kfree()'ed. */
+static char *join(const char *dir, const char *name)
+{
+       char *buffer;
+
+       if (strlen(name) == 0)
+               buffer = kasprintf(GFP_KERNEL, "%s", dir);
+       else
+               buffer = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
+       return (!buffer) ? ERR_PTR(-ENOMEM) : buffer;
+}
+
+static char **split(char *strings, unsigned int len, unsigned int *num)
+{
+       char *p, **ret;
+
+       /* Count the strings. */
+       *num = count_strings(strings, len);
+
+       /* Transfer to one big alloc for easy freeing. */
+       ret = kmalloc(*num * sizeof(char *) + len, GFP_KERNEL);
+       if (!ret) {
+               kfree(strings);
+               return ERR_PTR(-ENOMEM);
+       }
+       memcpy(&ret[*num], strings, len);
+       kfree(strings);
+
+       strings = (char *)&ret[*num];
+       for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1)
+               ret[(*num)++] = p;
+
+       return ret;
+}
+
+char **xenbus_directory(struct xenbus_transaction t,
+                       const char *dir, const char *node, unsigned int *num)
+{
+       char *strings, *path;
+       unsigned int len;
+
+       path = join(dir, node);
+       if (IS_ERR(path))
+               return (char **)path;
+
+       strings = xs_single(t, XS_DIRECTORY, path, &len);
+       kfree(path);
+       if (IS_ERR(strings))
+               return (char **)strings;
+
+       return split(strings, len, num);
+}
+EXPORT_SYMBOL_GPL(xenbus_directory);
+
+/* Check if a path exists. Return 1 if it does. */
+int xenbus_exists(struct xenbus_transaction t,
+                 const char *dir, const char *node)
+{
+       char **d;
+       int dir_n;
+
+       d = xenbus_directory(t, dir, node, &dir_n);
+       if (IS_ERR(d))
+               return 0;
+       kfree(d);
+       return 1;
+}
+EXPORT_SYMBOL_GPL(xenbus_exists);
+
+/* Get the value of a single file.
+ * Returns a kmalloced value: call free() on it after use.
+ * len indicates length in bytes.
+ */
+void *xenbus_read(struct xenbus_transaction t,
+                 const char *dir, const char *node, unsigned int *len)
+{
+       char *path;
+       void *ret;
+
+       path = join(dir, node);
+       if (IS_ERR(path))
+               return (void *)path;
+
+       ret = xs_single(t, XS_READ, path, len);
+       kfree(path);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_read);
+
+/* Write the value of a single file.
+ * Returns -err on failure.
+ */
+int xenbus_write(struct xenbus_transaction t,
+                const char *dir, const char *node, const char *string)
+{
+       const char *path;
+       struct kvec iovec[2];
+       int ret;
+
+       path = join(dir, node);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       iovec[0].iov_base = (void *)path;
+       iovec[0].iov_len = strlen(path) + 1;
+       iovec[1].iov_base = (void *)string;
+       iovec[1].iov_len = strlen(string);
+
+       ret = xs_error(xs_talkv(t, XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL));
+       kfree(path);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_write);
+
+/* Create a new directory. */
+int xenbus_mkdir(struct xenbus_transaction t,
+                const char *dir, const char *node)
+{
+       char *path;
+       int ret;
+
+       path = join(dir, node);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       ret = xs_error(xs_single(t, XS_MKDIR, path, NULL));
+       kfree(path);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_mkdir);
+
+/* Destroy a file or directory (directories must be empty). */
+int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node)
+{
+       char *path;
+       int ret;
+
+       path = join(dir, node);
+       if (IS_ERR(path))
+               return PTR_ERR(path);
+
+       ret = xs_error(xs_single(t, XS_RM, path, NULL));
+       kfree(path);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_rm);
+
+/* Start a transaction: changes by others will not be seen during this
+ * transaction, and changes will not be visible to others until end.
+ */
+int xenbus_transaction_start(struct xenbus_transaction *t)
+{
+       char *id_str;
+
+       down_read(&xs_state.suspend_mutex);
+
+       id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL);
+       if (IS_ERR(id_str)) {
+               up_read(&xs_state.suspend_mutex);
+               return PTR_ERR(id_str);
+       }
+
+       t->id = simple_strtoul(id_str, NULL, 0);
+       kfree(id_str);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(xenbus_transaction_start);
+
+/* End a transaction.
+ * If abandon is true, transaction is discarded instead of committed.
+ */
+int xenbus_transaction_end(struct xenbus_transaction t, int abort)
+{
+       char abortstr[2];
+       int err;
+
+       if (abort)
+               strcpy(abortstr, "F");
+       else
+               strcpy(abortstr, "T");
+
+       err = xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
+
+       up_read(&xs_state.suspend_mutex);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(xenbus_transaction_end);
+
+/* Single read and scanf: returns -errno or num scanned. */
+int xenbus_scanf(struct xenbus_transaction t,
+                const char *dir, const char *node, const char *fmt, ...)
+{
+       va_list ap;
+       int ret;
+       char *val;
+
+       val = xenbus_read(t, dir, node, NULL);
+       if (IS_ERR(val))
+               return PTR_ERR(val);
+
+       va_start(ap, fmt);
+       ret = vsscanf(val, fmt, ap);
+       va_end(ap);
+       kfree(val);
+       /* Distinctive errno. */
+       if (ret == 0)
+               return -ERANGE;
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_scanf);
+
+/* Single printf and write: returns -errno or 0. */
+int xenbus_printf(struct xenbus_transaction t,
+                 const char *dir, const char *node, const char *fmt, ...)
+{
+       va_list ap;
+       int ret;
+#define PRINTF_BUFFER_SIZE 4096
+       char *printf_buffer;
+
+       printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
+       if (printf_buffer == NULL)
+               return -ENOMEM;
+
+       va_start(ap, fmt);
+       ret = vsnprintf(printf_buffer, PRINTF_BUFFER_SIZE, fmt, ap);
+       va_end(ap);
+
+       BUG_ON(ret > PRINTF_BUFFER_SIZE-1);
+       ret = xenbus_write(t, dir, node, printf_buffer);
+
+       kfree(printf_buffer);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_printf);
+
+/* Takes tuples of names, scanf-style args, and void **, NULL terminated. */
+int xenbus_gather(struct xenbus_transaction t, const char *dir, ...)
+{
+       va_list ap;
+       const char *name;
+       int ret = 0;
+
+       va_start(ap, dir);
+       while (ret == 0 && (name = va_arg(ap, char *)) != NULL) {
+               const char *fmt = va_arg(ap, char *);
+               void *result = va_arg(ap, void *);
+               char *p;
+
+               p = xenbus_read(t, dir, name, NULL);
+               if (IS_ERR(p)) {
+                       ret = PTR_ERR(p);
+                       break;
+               }
+               if (fmt) {
+                       if (sscanf(p, fmt, result) == 0)
+                               ret = -EINVAL;
+                       kfree(p);
+               } else
+                       *(char **)result = p;
+       }
+       va_end(ap);
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_gather);
+
+static int xs_watch(const char *path, const char *token)
+{
+       struct kvec iov[2];
+
+       iov[0].iov_base = (void *)path;
+       iov[0].iov_len = strlen(path) + 1;
+       iov[1].iov_base = (void *)token;
+       iov[1].iov_len = strlen(token) + 1;
+
+       return xs_error(xs_talkv(XBT_NIL, XS_WATCH, iov,
+                                ARRAY_SIZE(iov), NULL));
+}
+
+static int xs_unwatch(const char *path, const char *token)
+{
+       struct kvec iov[2];
+
+       iov[0].iov_base = (char *)path;
+       iov[0].iov_len = strlen(path) + 1;
+       iov[1].iov_base = (char *)token;
+       iov[1].iov_len = strlen(token) + 1;
+
+       return xs_error(xs_talkv(XBT_NIL, XS_UNWATCH, iov,
+                                ARRAY_SIZE(iov), NULL));
+}
+
+static struct xenbus_watch *find_watch(const char *token)
+{
+       struct xenbus_watch *i, *cmp;
+
+       cmp = (void *)simple_strtoul(token, NULL, 16);
+
+       list_for_each_entry(i, &watches, list)
+               if (i == cmp)
+                       return i;
+
+       return NULL;
+}
+
+/* Register callback to watch this node. */
+int register_xenbus_watch(struct xenbus_watch *watch)
+{
+       /* Pointer in ascii is the token. */
+       char token[sizeof(watch) * 2 + 1];
+       int err;
+
+       sprintf(token, "%lX", (long)watch);
+
+       down_read(&xs_state.suspend_mutex);
+
+       spin_lock(&watches_lock);
+       BUG_ON(find_watch(token));
+       list_add(&watch->list, &watches);
+       spin_unlock(&watches_lock);
+
+       err = xs_watch(watch->node, token);
+
+       /* Ignore errors due to multiple registration. */
+       if ((err != 0) && (err != -EEXIST)) {
+               spin_lock(&watches_lock);
+               list_del(&watch->list);
+               spin_unlock(&watches_lock);
+       }
+
+       up_read(&xs_state.suspend_mutex);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(register_xenbus_watch);
+
+void unregister_xenbus_watch(struct xenbus_watch *watch)
+{
+       struct xs_stored_msg *msg, *tmp;
+       char token[sizeof(watch) * 2 + 1];
+       int err;
+
+       sprintf(token, "%lX", (long)watch);
+
+       down_read(&xs_state.suspend_mutex);
+
+       spin_lock(&watches_lock);
+       BUG_ON(!find_watch(token));
+       list_del(&watch->list);
+       spin_unlock(&watches_lock);
+
+       err = xs_unwatch(watch->node, token);
+       if (err)
+               printk(KERN_WARNING
+                      "XENBUS Failed to release watch %s: %i\n",
+                      watch->node, err);
+
+       up_read(&xs_state.suspend_mutex);
+
+       /* Make sure there are no callbacks running currently (unless
+          its us) */
+       if (current->pid != xenwatch_pid)
+               mutex_lock(&xenwatch_mutex);
+
+       /* Cancel pending watch events. */
+       spin_lock(&watch_events_lock);
+       list_for_each_entry_safe(msg, tmp, &watch_events, list) {
+               if (msg->u.watch.handle != watch)
+                       continue;
+               list_del(&msg->list);
+               kfree(msg->u.watch.vec);
+               kfree(msg);
+       }
+       spin_unlock(&watch_events_lock);
+
+       if (current->pid != xenwatch_pid)
+               mutex_unlock(&xenwatch_mutex);
+}
+EXPORT_SYMBOL_GPL(unregister_xenbus_watch);
+
+void xs_suspend(void)
+{
+       struct xenbus_watch *watch;
+       char token[sizeof(watch) * 2 + 1];
+
+       down_write(&xs_state.suspend_mutex);
+
+       /* No need for watches_lock: the suspend_mutex is sufficient. */
+       list_for_each_entry(watch, &watches, list) {
+               sprintf(token, "%lX", (long)watch);
+               xs_unwatch(watch->node, token);
+       }
+
+       mutex_lock(&xs_state.request_mutex);
+}
+
+void xs_resume(void)
+{
+       struct xenbus_watch *watch;
+       char token[sizeof(watch) * 2 + 1];
+
+       mutex_unlock(&xs_state.request_mutex);
+
+       /* No need for watches_lock: the suspend_mutex is sufficient. */
+       list_for_each_entry(watch, &watches, list) {
+               sprintf(token, "%lX", (long)watch);
+               xs_watch(watch->node, token);
+       }
+
+       up_write(&xs_state.suspend_mutex);
+}
+
+static int xenwatch_thread(void *unused)
+{
+       struct list_head *ent;
+       struct xs_stored_msg *msg;
+
+       for (;;) {
+               wait_event_interruptible(watch_events_waitq,
+                                        !list_empty(&watch_events));
+
+               if (kthread_should_stop())
+                       break;
+
+               mutex_lock(&xenwatch_mutex);
+
+               spin_lock(&watch_events_lock);
+               ent = watch_events.next;
+               if (ent != &watch_events)
+                       list_del(ent);
+               spin_unlock(&watch_events_lock);
+
+               if (ent != &watch_events) {
+                       msg = list_entry(ent, struct xs_stored_msg, list);
+                       msg->u.watch.handle->callback(
+                               msg->u.watch.handle,
+                               (const char **)msg->u.watch.vec,
+                               msg->u.watch.vec_size);
+                       kfree(msg->u.watch.vec);
+                       kfree(msg);
+               }
+
+               mutex_unlock(&xenwatch_mutex);
+       }
+
+       return 0;
+}
+
+static int process_msg(void)
+{
+       struct xs_stored_msg *msg;
+       char *body;
+       int err;
+
+       msg = kmalloc(sizeof(*msg), GFP_KERNEL);
+       if (msg == NULL)
+               return -ENOMEM;
+
+       err = xb_read(&msg->hdr, sizeof(msg->hdr));
+       if (err) {
+               kfree(msg);
+               return err;
+       }
+
+       body = kmalloc(msg->hdr.len + 1, GFP_KERNEL);
+       if (body == NULL) {
+               kfree(msg);
+               return -ENOMEM;
+       }
+
+       err = xb_read(body, msg->hdr.len);
+       if (err) {
+               kfree(body);
+               kfree(msg);
+               return err;
+       }
+       body[msg->hdr.len] = '\0';
+
+       if (msg->hdr.type == XS_WATCH_EVENT) {
+               msg->u.watch.vec = split(body, msg->hdr.len,
+                                        &msg->u.watch.vec_size);
+               if (IS_ERR(msg->u.watch.vec)) {
+                       kfree(msg);
+                       return PTR_ERR(msg->u.watch.vec);
+               }
+
+               spin_lock(&watches_lock);
+               msg->u.watch.handle = find_watch(
+                       msg->u.watch.vec[XS_WATCH_TOKEN]);
+               if (msg->u.watch.handle != NULL) {
+                       spin_lock(&watch_events_lock);
+                       list_add_tail(&msg->list, &watch_events);
+                       wake_up(&watch_events_waitq);
+                       spin_unlock(&watch_events_lock);
+               } else {
+                       kfree(msg->u.watch.vec);
+                       kfree(msg);
+               }
+               spin_unlock(&watches_lock);
+       } else {
+               msg->u.reply.body = body;
+               spin_lock(&xs_state.reply_lock);
+               list_add_tail(&msg->list, &xs_state.reply_list);
+               spin_unlock(&xs_state.reply_lock);
+               wake_up(&xs_state.reply_waitq);
+       }
+
+       return 0;
+}
+
+static int xenbus_thread(void *unused)
+{
+       int err;
+
+       for (;;) {
+               err = process_msg();
+               if (err)
+                       printk(KERN_WARNING "XENBUS error %d while reading "
+                              "message\n", err);
+               if (kthread_should_stop())
+                       break;
+       }
+
+       return 0;
+}
+
+int xs_init(void)
+{
+       int err;
+       struct task_struct *task;
+
+       INIT_LIST_HEAD(&xs_state.reply_list);
+       spin_lock_init(&xs_state.reply_lock);
+       init_waitqueue_head(&xs_state.reply_waitq);
+
+       mutex_init(&xs_state.request_mutex);
+       init_rwsem(&xs_state.suspend_mutex);
+
+       /* Initialize the shared memory rings to talk to xenstored */
+       err = xb_init_comms();
+       if (err)
+               return err;
+
+       task = kthread_run(xenwatch_thread, NULL, "xenwatch");
+       if (IS_ERR(task))
+               return PTR_ERR(task);
+       xenwatch_pid = task->pid;
+
+       task = kthread_run(xenbus_thread, NULL, "xenbus");
+       if (IS_ERR(task))
+               return PTR_ERR(task);
+
+       return 0;
+}
===================================================================
--- a/include/asm-i386/xen/hypervisor.h
+++ b/include/asm-i386/xen/hypervisor.h
@@ -42,6 +42,7 @@
 
 #include <asm/ptrace.h>
 #include <asm/page.h>
+#include <asm/desc.h>
 #if defined(__i386__)
 #  ifdef CONFIG_X86_PAE
 #   include <asm-generic/pgtable-nopud.h>
===================================================================
--- /dev/null
+++ b/include/xen/xenbus.h
@@ -0,0 +1,208 @@
+/******************************************************************************
+ * xenbus.h
+ *
+ * Talks to Xen Store to figure out what devices we have.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ * Copyright (C) 2005 XenSource Ltd.
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef _XEN_XENBUS_H
+#define _XEN_XENBUS_H
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/mutex.h>
+#include <linux/completion.h>
+#include <linux/init.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/grant_table.h>
+#include <xen/interface/io/xenbus.h>
+#include <xen/interface/io/xs_wire.h>
+
+/* Register callback to watch this node. */
+struct xenbus_watch
+{
+       struct list_head list;
+
+       /* Path being watched. */
+       const char *node;
+
+       /* Callback (executed in a process context with no locks held). */
+       void (*callback)(struct xenbus_watch *,
+                        const char **vec, unsigned int len);
+};
+
+
+/* A xenbus device. */
+struct xenbus_device {
+       const char *devicetype;
+       const char *nodename;
+       const char *otherend;
+       int otherend_id;
+       struct xenbus_watch otherend_watch;
+       struct device dev;
+       enum xenbus_state state;
+       struct completion down;
+};
+
+static inline struct xenbus_device *to_xenbus_device(struct device *dev)
+{
+       return container_of(dev, struct xenbus_device, dev);
+}
+
+struct xenbus_device_id
+{
+       /* .../device/<device_type>/<identifier> */
+       char devicetype[32];    /* General class of device. */
+};
+
+/* A xenbus driver. */
+struct xenbus_driver {
+       char *name;
+       struct module *owner;
+       const struct xenbus_device_id *ids;
+       int (*probe)(struct xenbus_device *dev,
+                    const struct xenbus_device_id *id);
+       void (*otherend_changed)(struct xenbus_device *dev,
+                                enum xenbus_state backend_state);
+       int (*remove)(struct xenbus_device *dev);
+       int (*suspend)(struct xenbus_device *dev);
+       int (*resume)(struct xenbus_device *dev);
+       int (*uevent)(struct xenbus_device *, char **, int, char *, int);
+       struct device_driver driver;
+       int (*read_otherend_details)(struct xenbus_device *dev);
+};
+
+static inline struct xenbus_driver *to_xenbus_driver(struct device_driver *drv)
+{
+       return container_of(drv, struct xenbus_driver, driver);
+}
+
+int xenbus_register_frontend(struct xenbus_driver *drv);
+int xenbus_register_backend(struct xenbus_driver *drv);
+void xenbus_unregister_driver(struct xenbus_driver *drv);
+
+struct xenbus_transaction
+{
+       u32 id;
+};
+
+/* Nil transaction ID. */
+#define XBT_NIL ((struct xenbus_transaction) { 0 })
+
+int __init xenbus_dev_init(void);
+
+char **xenbus_directory(struct xenbus_transaction t,
+                       const char *dir, const char *node, unsigned int *num);
+void *xenbus_read(struct xenbus_transaction t,
+                 const char *dir, const char *node, unsigned int *len);
+int xenbus_write(struct xenbus_transaction t,
+                const char *dir, const char *node, const char *string);
+int xenbus_mkdir(struct xenbus_transaction t,
+                const char *dir, const char *node);
+int xenbus_exists(struct xenbus_transaction t,
+                 const char *dir, const char *node);
+int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node);
+int xenbus_transaction_start(struct xenbus_transaction *t);
+int xenbus_transaction_end(struct xenbus_transaction t, int abort);
+
+/* Single read and scanf: returns -errno or num scanned if > 0. */
+int xenbus_scanf(struct xenbus_transaction t,
+                const char *dir, const char *node, const char *fmt, ...)
+       __attribute__((format(scanf, 4, 5)));
+
+/* Single printf and write: returns -errno or 0. */
+int xenbus_printf(struct xenbus_transaction t,
+                 const char *dir, const char *node, const char *fmt, ...)
+       __attribute__((format(printf, 4, 5)));
+
+/* Generic read function: NULL-terminated triples of name,
+ * sprintf-style type string, and pointer. Returns 0 or errno.*/
+int xenbus_gather(struct xenbus_transaction t, const char *dir, ...);
+
+/* notifer routines for when the xenstore comes up */
+extern int xenstored_ready;
+int register_xenstore_notifier(struct notifier_block *nb);
+void unregister_xenstore_notifier(struct notifier_block *nb);
+
+int register_xenbus_watch(struct xenbus_watch *watch);
+void unregister_xenbus_watch(struct xenbus_watch *watch);
+void xs_suspend(void);
+void xs_resume(void);
+
+/* Used by xenbus_dev to borrow kernel's store connection. */
+void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg);
+
+/* Called from xen core code. */
+void xenbus_suspend(void);
+void xenbus_resume(void);
+void xenbus_probe(struct work_struct *);
+
+#define XENBUS_IS_ERR_READ(str) ({                     \
+       if (!IS_ERR(str) && strlen(str) == 0) {         \
+               kfree(str);                             \
+               str = ERR_PTR(-ERANGE);                 \
+       }                                               \
+       IS_ERR(str);                                    \
+})
+
+#define XENBUS_EXIST_ERR(err) ((err) == -ENOENT || (err) == -ERANGE)
+
+int xenbus_watch_path(struct xenbus_device *dev, const char *path,
+                     struct xenbus_watch *watch,
+                     void (*callback)(struct xenbus_watch *,
+                                      const char **, unsigned int));
+int xenbus_watch_path2(struct xenbus_device *dev, const char *path,
+                      const char *path2, struct xenbus_watch *watch,
+                      void (*callback)(struct xenbus_watch *,
+                                       const char **, unsigned int));
+int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state 
new_state);
+int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn);
+int xenbus_map_ring_valloc(struct xenbus_device *dev,
+                          int gnt_ref, void **vaddr);
+int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
+                          grant_handle_t *handle, void *vaddr);
+
+int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr);
+int xenbus_unmap_ring(struct xenbus_device *dev,
+                     grant_handle_t handle, void *vaddr);
+
+int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port);
+int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port);
+int xenbus_free_evtchn(struct xenbus_device *dev, int port);
+
+enum xenbus_state xenbus_read_driver_state(const char *path);
+
+void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, 
...);
+void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, 
...);
+
+char *xenbus_strstate(enum xenbus_state state);
+int xenbus_dev_is_online(struct xenbus_device *dev);
+int xenbus_frontend_closed(struct xenbus_device *dev);
+
+#endif /* _XEN_XENBUS_H */

-- 


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>