Re: [Xen-devel] making changes to agp code?

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> "Langsdorf, Mark" <mark.langsdorf@xxxxxxx> 26.03.07 22:03 >>>
>As part of my endless quest to enable GART/IOMMU, I
>realized I need to make a slight change to a static
>function inside of agp-amd64.c.  Currently Xen doesn't
>have -xen variants of the AGP code.  Is there a 
>better way to handle this than sucking in the entire
>AGP tree into xen-sparse?

If the change is as small as you describe, I'd suggest doing it in the
file itself by means of adding a patch in patches/linux-2.6.18/, with
the change properly protected by #ifdef CONFIG_XEN or alike.

>As far what I need to change:
>   pci-gart calls agp_amd64_init() to determine if
>the aperture is provided by the BIOS, or if one 
>needs to be allocated.  agp_amd64_init() calls
>agp_amd64_probe() which calls another function
>and so forth, and eventually aperture_valid()
>calls 
>PageReserved(pfn_to_page(aperture >> PAGE_SHIFT)).
>The page isn't actually reserved, but dom0 thinks
>it is, and the operation fails.  I would like to
>do something more intelligent.

>From that description I'm getting afraid that this code is currently
broken anyway, i.e. the change you intend to make is needed
immediately and regardless of your iommu work. May I ask what
your intended replacement is?

Jan

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