lkml.org 
[lkml]   [2008]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [Q] Why does dma_alloc_coherent() of ia64 GFP_DMA?
From
On Mon, 10 Nov 2008 16:06:52 -0600 (CST)
Christoph Lameter <cl@linux-foundation.org> wrote:

> On Mon, 10 Nov 2008, Yasunori Goto wrote:
>
> > Even if a device allows over 4G access and the driver doesn't specify
> > GFP_DMA, dma_alloc_coherent() returns under 4G area.
>
> GFP_DMA can become 0 for configurations that have
> !CONFIG_ZONE_DMA. Then all of memory is available.
>
> The call is subarch specific. So f.e. Altix sn_dma_alloc_coherent does
> not set __GFP_DMA.

Is it because it does some kinda address translation
(provider->dma_map_consistent) later? The zone flag is meaningless if
you do sorta address translation (e.g. hardware IOMMU like VT-d).


\
 
 \ /
  Last update: 2008-11-11 06:57    [W:0.147 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site