Attachment 311256 Details for Bug 454417 – RHEL4 fix for this issue [v2]

[patch] RHEL4 fix for this issue [v2]

454417.patch (text/plain), 1.14 KB, created by Prarit Bhargava on 2008-07-08 12:06:03 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Prarit Bhargava

Created: 2008-07-08 12:06:03 UTC

Size: 1.14 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..dac68bf 100644
>--- a/Documentation/DMA-mapping.txt
>+++ b/Documentation/DMA-mapping.txt
>@@ -339,13 +339,6 @@ pci_alloc_consistent returns two values: the virtual address which you
> 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.
>-
> To unmap and free such a DMA region, you call:
> 
> 	pci_free_consistent(dev, size, cpu_addr, dma_handle);

Actions: View | Diff

Attachments on bug 454417: 311255 | 311256 | 311259