Re: Xen 3.0 Status update

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

On Fri, Jul 29, 2005 at 12:05:10AM +0100, Ian Pratt wrote:

> > > 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.
> 
> The hypercall should probably pass in the 'order' of the address limit
> required for the allocation. There are a few stupid devices that require
> memory below 2GB etc (e.g. aacraid)

This is with the MEMOP_decrease_reservation hypercall, which is already
using up all of its allotted arguments. Its been a while, but it didn't
look like it was going to be real easy to raise the limit of 6 arguments
on x86_32.

> > 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)
> 
> Can you give examples? What size are the allocations? Do you know what
> the official position is i.e. is using kmalloc with ZONE_DMA deprecated?

I have no idea about official positions of the linux kernel.

sRp

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