amd64 agp driver bug?

[Jung-uk Kim]

On Saturday 07 October 2006 05:43 pm, John-Mark Gurney wrote:
> I was looking at the agp driver and the BIOS and Kernel Developer's
> Guide, and noticed that it appears we program the page register
> incorrectly...
>
> Currently we do, in sys/pci/agp_amd64.c:
>         sc->gatt->ag_virtual[offset >> AGP_PAGE_SHIFT] = physical;
>
> but according to Table 38 in the guide, it looks like it should be:
>         sc->gatt->ag_virtual[offset >> AGP_PAGE_SHIFT] =
>             (physical & 0xfffff000) | ((physical >> 28) & 0xff0) |
> 1;
>
> To support physical addresses above 4G...
>
> Has anyone used AGP w/ >4GB of memmory?  I'm also puzzled by the
> fact that the guide says to set bit 0, but we don't do that...

As you can see, this part of the documentation is very 
confusing. :-(  I'll take care of it soon.

Jung-uk Kim