[Xen-devel] [PATCH] give xen dma zones

["Scott Parish" <srparish@xxxxxxxxxx>]

Attached patch adds a DMA zone to xen, also modifies xen_contig_memory()
to ask for DMA pages.

sRp

On Fri, Jul 29, 2005 at 12:31:42AM +0100, Ian Pratt 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.
> > > 
> > > 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.
> 
> extent_order only needs to be a byte parameter, so it would be
> reasonable to have the next byte of the word be the addr_limit_order.
> (We might want a separate alignment order in future too).
> 
> > > > 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.
> 
> I guess its probably allowed for sub page allocations. 
> 
> Hopefully the s/w iommu can take care of these at map time.
> 
> Ian 
> 
> 

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

Attachment: xen-dmazones.diff
Description: Text document

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