lkml.org 
[lkml]   [2003]   [Jul]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] block layer support for DMA IOMMU bypass mode II
On Wed, Jul 02, 2003 at 07:20:26PM +0200, Andi Kleen wrote:
...
> > Can two adjacent IOMMU entries be used to map two 1K buffers?
> > Assume the 1st buffer ends on a 4k alignment and the next one
> > starts on a 4k alignment.
>
> Yes, it could. But is that situation likely/worth to handle?

Probably. It would reduce the number of mappings by 25% (3 instead of 4).
My assumption is two adjecent IOMMU entries have contigious bus addresses.

I was trying to figure out if x86-64 should be setting
BIO_VMERGE_BOUNDARY to 0 or 4k.

It sounds like x86-64 could support "#define BIO_VMERGE_BOUNDARY 4096"
if the IOMMU code will return one DMA address for two SG list entries
in the above example.

hth,
grant
-
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: 2005-03-22 13:46    [W:2.126 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site