Re: Linux 2.6.39-rc3

[Yinghai Lu <yinghai@kernel.org>]

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",