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xen-users
RE: [Xen-users] 3D acceleration question (again)
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Andre.Weidemann@xxxxxx
> Sent: 08 December 2006 14:43
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] 3D acceleration question (again)
>
> Hi,
> I know this subject has been discussed several times here on the list
> before, but I'd like to bring it up again.
>
> From what I have read in the Wiki's FAQ and the list here, an IOMMU
> would cure the problem of translating the IO-Addresses for
> accessing the
> GFX card directly.
>
> From what I have read, the Pacifica architecture inside the AMD
> Athlon64s respectively the CPU's northbridge provides an IOMMU.
> Is this correct?
Not quite. There is a possibility to use the GART (Graphics Aperture
Redirection Table(??)) to translate one PCI (including PCI, PCI-x, PCI-e and
AGP[248]x) address to another physical memory address - this is used in the
Linux kernel to do IOMMU for memory buffers above 4GB to hardware that isn't
64-bit addressing.
I think Mark Langsdorf at AMD was working on a xenified version of this, but I
don't know what happened to that work. Unforutnately, the GART only translates
for ONE GUEST AT A TIME, so if you have a multiprocessor (or even multicore)
system, you can't have two guests use the GART translation (no problem in this
application, you'd probably only _WANT_ give the graphics card to ONE guest
anyways) which limits it's usefulness.
There are plans for a FULL IOMMU (actually, I'd expect this to be more than a
plan at this stage, but I don't know what the hardware guys are doing on this,
and _IF_ I did know, I couldn't tell anyone anyways... ;-) )
> Could this be used for the previously discussed address translations?
> If so, are there any plans yet on using this unit and could one get
> direct access to the GFX card so full hardware acceleration
> was possible?
As I said, there's been plans for it, but as of right now I don't know if it's
realistic to expect this to happen.
--
Mats
>
>
> Thank you in advance.
> André
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users
>
>
>
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