Re: Xen 3.0 Status update

["Scott Parish" <srparish@us.ibm.com>]

On Thu, Jul 28, 2005 at 11:39:46PM +0100, Ian Pratt wrote:

> > 
> > >  * Intel would get the standard s/w iommu working (just a case of 
> > > ensuring we have a machine contiguous aperture beloe 4GB -- 
> > the Linux 
> > > code currently uses the boot mem allocator rather than using 
> > > alloc_coherent, so it will need a little tweaking)
> > 
> > Yeah, i haven't had much luck so far.
> 
> I don't really understand why the aperture is allocated so early. I
> suspect its not actually used until the normal bootmem allocator is up. 
> 
> The slightly more fundamental problem is that we need a <4GB allocation
> zone in Xen, but since allocating the apperture is only currently an
> issue for dom0 it won't actually be a problem in practice. (something we
> need to address before driver domains come back)

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)

If the zones patch would be helpful i could clean it up and post it.

sRp

-- 
Scott Parish
Signed-off-by: srparish@us.ibm.com