Re: [PATCH] quiet down swiotlb warnings

Andi Kleen
2007-06-02T16:47:18Z

On Sat, Jun 02, 2007 at 06:21:46PM +0300, Muli Ben-Yehuda wrote:
> On Fri, Jun 01, 2007 at 10:26:01PM +0200, Andi Kleen wrote:
>
> > Normally swiotlb doesn't even try to bounce when dma mask is <=
> > end_pfn so something must be very wrong in your kernel. It
> > definitely isn't a mainline kernel. If this happens in Xen then Xen
> > just needs fixing -- it should not try to bounce when the normal
> > kernel wouldn't.
>
> Xen needs to bounce when the requested buffer is not contiguous in
> machine memory (and indeed uses swiotlb for that).

Then it should just restrict the sg list merging at the block layer
to never merge into anything larger than a page. Then this cannot
happen or only very rarely.

-Andi