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Subject[BUG] agpgart-amd64 not initialized in 2.6.33-rc2
Hi all,

Recently (2.6.33-rc2 kernel, x86_64, 4GB RAM) I found (in dmesg):

[drm:mga_do_agp_dma_bootstrap] *ERROR* Unable to acquire AGP: -19

and there is no /dev/agpgart device on the machine while all is OK
if booting

In both kernels I have:



but nevertheless dmesg shows:

PCI-DMA: Using software bounce buffering for IO (SWIOTLB)

due to quirks in via K8T800Pro host bridge.

Looking for the reason I found that agp_amd64_init() appears in:


/* so it is not invoked here due to CONFIG_GART_IOMMU=y */

and also appears in:

arch/x86/kernel/pci-gart_64.c, function: gart_iommu_init()

The last one is part of the struct x86_init_ops(struct x86_init_iommu, as a function pointer)
only if gart-iommu is successfully detected, which is not the case here due to the quirk,
so agp_amd64_init() is not invoked here neither.

Sure, configuring the kernel without CONFIG_GART_IOMMU=y (which is not user selectable)

should solve the problem, but usually users do not know about quirks, so it should
work even as set here (and it works up to I believe the bug is introduced
with the changes in the order iommu detect/init works for 2.6.33.

I am here for additional info/tests.

Best regards

Marin Mitov

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