On 04/13/2011 12:34 PM, Joerg Roedel wrote: > On Wed, Apr 13, 2011 at 12:14:55PM -0700, Yinghai Lu wrote: >> thanks for the bisecting... >> >> so those two patches uncover some problems. >> >> [ 0.000000] Checking aperture... >> [ 0.000000] No AGP bridge found >> [ 0.000000] Node 0: aperture @ a0000000 size 32 MB >> [ 0.000000] Aperture pointing to e820 RAM. Ignoring. >> [ 0.000000] Your BIOS doesn't leave a aperture memory hole >> [ 0.000000] Please enable the IOMMU option in the BIOS setup >> [ 0.000000] This costs you 64 MB of RAM >> [ 0.000000] memblock_x86_reserve_range: [0xa0000000-0xa3ffffff] aperture64 >> [ 0.000000] Mapping aperture over 65536 KB of RAM @ a0000000 >> >> so kernel try to reallocate apperture. because BIOS allocated is pointed to RAM or size is too small. > > It is actually beyond 4GB on that machine, this value read here is from > the previous kernel-boot. The BIOS does not reset these values on a > reboot. > >> but your radeon does use [0xa0000000, 0xbfffffff) > > Yes, I suspected that too (and spent a few hours reading radeon code), > but then I talked the Alex Deucher and he explained that these addresses > which the driver prints for GTT and VRAM are in the GPU address space > and do not refer to system ram. So this shouldn't be the problem. can you try following change ? it will push gart to 0x80000000 diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c index 86d1ad4..3b6a9d5 100644 --- a/arch/x86/kernel/aperture_64.c +++ b/arch/x86/kernel/aperture_64.c @@ -83,7 +83,7 @@ static u32 __init allocate_aperture(void) * so don't use 512M below as gart iommu, leave the space for kernel * code for safe */ - addr = memblock_find_in_range(0, 1ULL<<32, aper_size, 512ULL<<20); + addr = memblock_find_in_range(0, 1ULL<<32, aper_size, 512ULL<<21); if (addr == MEMBLOCK_ERROR || addr + aper_size > 0xffffffff) { printk(KERN_ERR "Cannot allocate aperture memory hole (%lx,%uK)\n", _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel