Re: [Xen-devel] Xen Dom U kernel

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Apr 19, 2010 at 12:08:35PM -0700, kishore kumar wrote:
>    I included
>    kernel = "/boot/vmlinuz-2.6.32.10"
>    ramdisk = "/boot/initrd-2.6.32.10.img" (This is the same as my Dom 0.  As
>    I am trying to boot the same Dom 0 as my Dom U without any changes)
>

You cannot use the dom0 initrd/ramdisk for domU!

dom0 initrd contains drivers for the physical hardware, while in the domU initrd
you need to have drivers for the _virtual_ hardware!

In the log below root was not found because the drivers for the xen block 
devices
are not loaded.

-- Pasi


>    disk = ['phy:sda2,sda2,w']
>    root= "/dev/VolGroup01/LogVol00 ro"
> 
>      I see my .config and I have
>    CONFIG_XEN_BLKDEV_FRONTEND=m
>    CONFIG_XEN_BLKDEV_BACKEND=y
>    CONFIG_XEN_BACKEND=y
> 
>    Below is the output pasted.  Any help please on what is going wrong here?
> 
>    XENBUS: Device with no driver: device/vbd/2050
> 
>    XENBUS: Device with no driver: device/vif/0
> 
>    XENBUS: Device with no driver: device/console/0
> 
>    Magic number: 1:252:3141
> 
>    drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
> 
>    Initalizing network drop monitor service
> 
>    Freeing unused kernel memory: 3392k freed
> 
>    Write protecting the kernel read-only data: 6912k
> 
>    Red Hat nash version 5.1.19.6 starting
> 
>    Mounting proc filesystem
> 
>    Mounting sysfs filesystem
> 
>    Creating /dev
> 
>    Creating initial device nodes
> 
>    Setting up hotplug.
> 
>    Creating block device nodes.
> 
>    Loading ehci-hcd.ko module
> 
>    ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
> 
>    insmod used greatest stack depth: 5712 bytes left
> 
>    Loading ssb.ko module
> 
>    Loading ohci-hcd.ko module
> 
>    ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
> 
>    Loading uhci-hcd.ko module
> 
>    uhci_hcd: USB Universal Host Controller Interface driver
> 
>    Scanning and configuring dmraid supported devices
> 
>    Scanning logical volumes
> 
>    Reading all physical volumes. This may take a while...
> 
>    lvm used greatest stack depth: 5328 bytes left
> 
>    Activating logical volumes
> 
>    Volume group "VolGroup01" not found
> 
>    Trying to resume from /dev/VolGroup01/LogVol01
> 
>    Unable to access resume device (/dev/VolGroup01/LogVol01)
> 
>    Creating root device.
> 
>    Mounting root filesystem.
> 
>    mount: could not find filesystem '/dev/root'
> 
>    Setting up other filesystems.
> 
>    Setting up new root fs
> 
>    setuproot: moving /dev failed: No such file or directory
> 
>    no fstab.sys, mounting internal defaults
> 
>    setuproot: error mounting /proc: No such file or directory
> 
>    setuproot: error mounting /sys: No such file or directory
> 
>    Switching to new root and running init.
> 
>    unmounting old /dev
> 
>    unmounting old /proc
> 
>    unmounting old /sys
> 
>    switchroot: mount failed: No such file or directory
> 
>    init used greatest stack depth: 4888 bytes left
> 
>    Kernel panic - not syncing: Attempted to kill init!
> 
>    Pid: 1, comm: init Not tainted 2.6.32.10 #2
> 
>    Call Trace:
> 
>    [<ffffffff8105b747>] panic+0xa5/0x167
> 
>    [<ffffffff8100ed81>] ? xen_force_evtchn_callback+0xd/0xf
> 
>    [<ffffffff81475d48>] ? _write_unlock_irq+0x30/0x3c
> 
>    [<ffffffff8108c9f4>] ? trace_hardirqs_on_caller+0x110/0x134
> 
>    [<ffffffff8108ca25>] ? trace_hardirqs_on+0xd/0xf
> 
>    [<ffffffff81475d4f>] ? _write_unlock_irq+0x37/0x3c
> 
>    [<ffffffff8105efa7>] do_exit+0x7e/0x701
> 
>    [<ffffffff8105f6c6>] sys_exit_group+0x0/0x1b
> 
>    [<ffffffff8105f6dd>] sys_exit_group+0x17/0x1b
> 
>    [<ffffffff81012d72>] system_call_fastpath+0x16/0x1b
> 
>    On Sat, Apr 17, 2010 at 5:22 AM, Pasi Kärkkäinen <[1]pasik@xxxxxx> wrote:
> 
>      On Fri, Apr 16, 2010 at 03:24:53PM -0700, kishore kumar wrote:
>      >    I am using my Dom 0 kernel to boot as my Dom U.
>      >    I edited /etc/xen/xmexample1 file and modified only below lines
>      >
>      >    kernel="/boot/vmlinux-2.6.32.10"
>      >    memory=512
>      >    vcpus=5
>      >    root = "/dev/VolGroup01/LogVol00 ro"
>      >    Below is the output I pasted after freezing.  Not sure what is
>      wrong.  Can
>      >    you please help me here??
>      >    I doubt if I have provided the correct root option?
>      >
> 
>      I bet that kernel has xen block frontend driver as a module?
> 
>      You don't seem to have ramdisk/initrd image,
>      so you simply don't have the driver loaded at all
>      to access the root disk in the guest.
> 
>      You must create an initrd image that loads the driver module in the
>      guest.
>      >
>      >    VFS: Cannot open root device "VolGroup01/LogVol00" or
>      unknown-block(0,0)
>      >
>      >    Please append a correct "root=" boot option; here are the available
>      >    partitions:
>      >
>      >    Kernel panic - not syncing: VFS: Unable to mount root fs on
>      >    unknown-block(0,0)
>      >
> 
>      Root was not found - this is usually because you don't have the xen
>      blockdev frontend driver loaded.
>      -- Pasi
> 
> References
> 
>    Visible links
>    1. mailto:pasik@xxxxxx

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