agp_i810 not built on amd64?

Eric Anholt eric at
Fri May 4 21:19:33 UTC 2007

On Fri, 2007-05-04 at 13:13 -0700, Nate Lawson wrote:
> I have a desktop with i945GMS builtin video.  It appears agp_i810.c is
> not built on amd64, hence no support for agp.  This is on 6.x.
> none0 at pci0:2:0: class=0x030000 card=0x31031565 chip=0x27728086 rev=0x02
> hdr=0x00
>     vendor     = 'Intel Corporation'
>     device     = 'Integrated Graphics Controller'
>     class      = display
>     subclass   = VGA
> sys/conf/files.i386:pci/agp_i810.c                     optional agp
> $ ls /sys/amd64/compile/SMP/*agp*
> /sys/amd64/compile/SMP/agp.o            /sys/amd64/compile/SMP/agp_if.h
> /sys/amd64/compile/SMP/agp_amd64.o      /sys/amd64/compile/SMP/agp_if.o
> /sys/amd64/compile/SMP/agp_if.c         /sys/amd64/compile/SMP/agp_intel.o
> Is there any reason not to use i810 on amd64?  A quick glance through
> doesn't show it doing anything 32-bit specific.  On -current, it appears
> to be enabled for amd64.  It appears this MFC never happened:
> revision 1.93
> date: 2006/09/05 16:55:12;  author: anholt;  state: Exp;  lines: +1 -0
> Include agp_i810.c in amd64 AGP builds to get support for the Intel 915
> Express chipsets.

Nope, there's no good reason for the MFC to have not happened.

We've only got one amd64 issue that I know of, but it's actually not
unique to amd64.  We're not allocating our pages to back aperture
allocations to meet the requirements of the page tables, so for example
on i915-class hardware with 4GB of ram, you'll get pages sometimes that
are above the 4GB range, and we'll just drop the top bit of the address
when filling in the page table, resulting in pain.  We need a way for
AGP drivers to communicate their requirements for AGP memory to the
core, likely through busdma tags.

In the current agp_i810.c patch I've been working on, I at least panic
when we get out-of-range pages, instead of scribbling on random memory.

Eric Anholt                             anholt at
eric at                         eric.anholt at

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