Attachment 311259 Details for Bug 454417 – RHEL4 fix for this issue [v3]

[patch] RHEL4 fix for this issue [v3]

454417.patch (text/plain), 1.06 KB, created by Prarit Bhargava on 2008-07-08 12:10:29 UTC

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Creator: Prarit Bhargava

Created: 2008-07-08 12:10:29 UTC

Size: 1.06 KB

patch

obsolete

>RHEL4's implementation of pci_alloc_consistent (and dma_alloc_coherent for
>that matter) does not guarantee alignment to anything other than PAGE_SIZE.
>
>There is an inconsistency in the Documentation -- the DMA-mapping.txt file was
>backported into RHEL4 and contains erroneous information about
>pci_alloc_consistent.
>
>Resolves BZ 454417.
>
>diff --git a/Documentation/DMA-mapping.txt b/Documentation/DMA-mapping.txt
>index f4ac37f..e447b3c 100644
>--- a/Documentation/DMA-mapping.txt
>+++ b/Documentation/DMA-mapping.txt
>@@ -340,11 +340,7 @@ can use to access it from the CPU and dma_handle which you pass to the
> card.
> 
> The cpu return address and the DMA bus master address are both
>-guaranteed to be aligned to the smallest PAGE_SIZE order which
>-is greater than or equal to the requested size.  This invariant
>-exists (for example) to guarantee that if you allocate a chunk
>-which is smaller than or equal to 64 kilobytes, the extent of the
>-buffer you receive will not cross a 64K boundary.
>+guaranteed to be aligned to PAGE_SIZE.
> 
> To unmap and free such a DMA region, you call:
>

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