Re: [Xen-devel] Xen 3.0 Status update

["Scott Parish" <srparish@xxxxxxxxxx>]

On Thu, Jul 28, 2005 at 11:57:27PM +0100, Mark Williamson wrote:

> > I have a patch that introduces zones into xen, and a hypercall to
> > request dmaable memory, which i've made xen_contig_memory() use.
> > Unfortunately, there still seems to be some places where kmallocs are
> > done for dma buffers. (i tried putting all linux memory into ZONE_NORMAL
> > and caught a couple of these places)
> 
> The Linux USB stack uses kmalloc-ed memory as DMA buffers as standard 
> practice.  This should still be dealt with correctly by bounce buffer code, 
> though.

I'll have to look at that code. The place i caught was
drivers/scsi/sd.c:1471:

        buffer = kmalloc(512, GFP_KERNEL | __GFP_DMA);

I've tried fixing the page allocator to xen_contig_memory() pages that
are requested __GFP_DMA, but now get a null pointer dereference i
haven't shaken out yet. (i'm not suggesting that xen_contig_memory() is
the appropriate long term solution, but for prototyping it should work)

sRp

-- 
Scott Parish
Signed-off-by: srparish@xxxxxxxxxx

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