Re: [Xen-ia64-devel] [RFC] paravirtualize stock swiotlb

[Alex Williamson <alex.williamson@xxxxxx>]

On Sun, 2007-04-29 at 14:17 +0900, Isaku Yamahata wrote:
> On Fri, Apr 27, 2007 at 06:13:07PM -0600, Alex Williamson wrote:
> > 
> >   We need to get to a CONFIG_IA64_GENERIC kernel working, and the first
> > step to doing that seems to be fixing our usage of the i386 swiotlb and
> > pci-dma-xen.  The patch below paravirtualizes lib/swiotlb.c and rips out
> > a lot of the code we had around for supporting the i386 versions.  It
> > should be a little more straight-forward to switch to the generic kernel
> > flavor after this.  This hasn't had much testing, so please don't run
> > this on a machine with data you care about.  I'm running it with
> > swiotlb=force to try to exercise it, and it's holding up well.  Comments
> > welcome.  Thanks,
> 
> Hi Alex.
> I fully agree with you that going to CONFIG_IA64_GENERIC instead
> of CONFIG_IA64_DIG is the way.
> Jan Beulich of Novel is trying the same issue as
> "swiotlb abstraction (e.g. for Xen)".
> Although I don't know its current status though, you may want to 
> talk with him. Or you already did?

   Thanks for the pointer, I went back and re-read the history and
started a conversation with Jan in a separate thread.  I'd prefer to use
a partualized lib/swiotlb.c, but I'm wondering if an interim solution
would be to put a paravirtualized copy of lib/swiotlb.c in arch/ia64/xen
and build that one instead of the i386 version.  It's obviously more
maintenance, but I don't want to get deadlocked waiting on a merge with
upstream Linux for us to be able to proceed with supporting machine
vectors.  Thoughts?  Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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