Bug#604096: Bug#602418: #601341, #602418 and #604096 seem to be duplicates
.. snip of back-history..
> > Thanks for the pointers.
> >
> > I agree with Bastian that some of these changes are really quite nasty.
> > Do you and other Xen developers have any plan for how to fix the GART
> > and TTM mapping problems in a cleaner way as Xen dom0 support goes
> > upstream?
>
> I know that there is a plan to get rid of the _PAGE_IOMAP stuff
> altogether by simply arranging for a 1-1 mapping for the relevant device
> PFNs in the P2M array. However I'm not sure whether or not this
> knocks-on into a fix for the GART/TTM stuff.
Unfortunately it won't fit the whole bill. What some of those patches
did was introduce a mechanism to "use" the PCI API to do virt_to_phys.
And when I say "use", I mean that really loosely. The solution I cobbled
was to bypass using any API and just hard-coded the phys->bus address
lookup. My plan for upstream is to actually work on those drivers
(intel-agp.c, agpgart.c) to utilize the PCI API.
>
> Konrad, do you have an idea how you plan to solve the GART/TTM issues
> upstream?
Yes, I am working on a set of patches that are cleaner and more upstream-able
than the first revision. Hope to have most of a) and b) done in the next two weeks.
And there are actually three distinct milestones here:
a) Fix the GART/AGP backend (so drivers/char/agp/*.c) so they use the PCI API.
Only the i915 and higher are using the PCI API and I've some of the older
boxes with i860 so can actually test it.
b) Fix the TTM to use the DMA API.
c) Lastly, get rid of _PAGE_IOMAP so we don't have to depend on radeon/nouveau/etc
to set the proper _PAGE_IOMAP on the PFNs/BARs..
>
> > If there is no such plan then I would rather disable these drivers than
> > make them work temporarily with a hack.
The shape of the stuff that I am going to propose upstream is more refined
and much cleaner. Do you want me to send you an email when I am ready
and had done my testing so you can take a look at it?
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