[lkml]   [2011]   [May]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Question about iommu on x86_64 and radeon driver.
On Wed, May 25, 2011 at 09:21:21PM +0100, Daniel Haid wrote:
> >Only if you allow 3GB or less in the machine. So you would have to do
> >mem=3G as well.
> >
> >The reason is that (and you can see that yourself by looking at the
> >E820), is that 1GB is actually _above_ the 4GB.
> Just another question on this one:
> Why can a driver not simply ask for DMA-capable memory, is this not
> what memory zones are for?

In many cases the memory gets passed into the driver.

If it's not already in the right boundaries it would need to copy through
a bounce buffer. That is what swiotlb does, if there's no IOMMU.


 \ /
  Last update: 2011-05-26 01:07    [W:0.079 / U:0.684 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site