lkml.org 
[lkml]   [2007]   [May]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Define CONFIG_BOUNCE to avoid useless inclusion of bounce buffer logic.
Christoph Lameter writes:

> > The DMA zone is for memory allocations _for_ _DMA_. If all your memory
> > is DMA-able then it belongs in the DMA zone.
>
> Nope. The DMA zone is for crappy DMA devices that can only use a portion
> of memory.

That is (presumably) true today, but is in fact a redefinition of what
ZONE_DMA historically was for.

Also there is the problem that some drivers use ZONE_DMA allocations
because their device can only generate addresses below some limit, but
on a platform with an IOMMU there is in fact no restriction on what
memory the device can access.

Paul.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-05-24 06:01    [from the cache]
©2003-2011 Jasper Spaans