[lkml]   [2007]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Define CONFIG_BOUNCE to avoid useless inclusion of bounce buffer logic.
On Wed, May 23, 2007 at 09:03:02PM -0700, Christoph Lameter wrote:
> On Thu, 24 May 2007, Paul Mackerras wrote:
> > 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.
> That problem is to some extend addressed by switching ZONE_DMA off which
> results in GFP_DMA becoming meaningless. And if GFP_DMA and ZONE_DMA is
> gone from a platform then the MAX_DMA_ADDRESS inconsistencies are solved
> since the cause of the inconsistencies has evaporated.

Suffice it to say then that with this approach ARM will _never_ be able
to have ZONE_DMA turned off, even on platforms where there are no DMA
restrictions. I guess that's something we'll just have to live with.

Russell King
Linux kernel 2.6 ARM Linux -
maintainer of:
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-06-04 00:27    [W:0.042 / U:1.824 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site