Kevin Winchester reported a GART related direct rendering failure against
linux-next-20080611, which shows up via these log entries:

 PCI: Using ACPI for IRQ routing
 PCI: Cannot allocate resource region 0 of device 0000:00:00.0
 agpgart: Detected AGP bridge 0
 agpgart: Aperture conflicts with PCI mapping.
 agpgart: Aperture from AGP @ e0000000 size 128 MB
 agpgart: Aperture conflicts with PCI mapping.
 agpgart: No usable aperture found.
 agpgart: Consider rebooting with iommu=memaper=2 to get a good aperture.

instead of the expected:

 PCI: Using ACPI for IRQ routing
 agpgart: Detected AGP bridge 0
 agpgart: Aperture from AGP @ e0000000 size 128 MB

Kevin bisected it down to this change in tip/x86/gart:
"x86: checking aperture size order".

agp check is using request_mem_region(), and could fail if e820 is reserved...

change it back to e820_any_mapped().
Reported-and-bisected-by: "Kevin Winchester" <kjwinchester@gmail.com>
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Tested-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>