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 07/10] xen/swiotlb: improve comment on gfp flags in x

To: Ingo Molnar <mingo@xxxxxxx>
Subject: [Xen-devel] [PATCH 07/10] xen/swiotlb: improve comment on gfp flags in xen_alloc_coherent()
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Tue, 12 May 2009 14:50:48 -0700
Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Joerg Roedel <joerg.roedel@xxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
Delivery-date: Tue, 12 May 2009 16:23:17 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <1242165051-6636-1-git-send-email-jeremy@xxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <1242165051-6636-1-git-send-email-jeremy@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

Clarify why we don't care about the kernel's pseudo-phys restrictions,
so long as the underlying pages are in the right place.

[ Impact: cleanup ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 drivers/pci/xen-iommu.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c
index bc64397..d09ff91 100644
--- a/drivers/pci/xen-iommu.c
+++ b/drivers/pci/xen-iommu.c
@@ -203,15 +203,17 @@ static void *xen_alloc_coherent(struct device *dev, 
size_t size,
        unsigned long vstart;
        u64 mask;
 
-       /* ignore region specifiers */
+       /*
+        * Ignore region specifiers - the kernel's ideas of
+        * pseudo-phys memory layout has nothing to do with the
+        * machine physical layout.  We can't allocate highmem
+        * because we can't return a pointer to it.
+        */
        gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
 
        if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
                return ret;
 
-       if (dev == NULL || (dev->coherent_dma_mask < DMA_BIT_MASK(32)))
-               gfp |= GFP_DMA;
-
        vstart = __get_free_pages(gfp, order);
        ret = (void *)vstart;
 
-- 
1.6.0.6


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