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pci-gart_64.c: could we get better explanation? 

Add better explanation to pci-gart.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Trivial patch monkey <trivial@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Pavel Machek 2008-06-26 00:25:43 +02:00 committed by Ingo Molnar
parent 037a6079eb
commit fa3d319ac6
1 changed files with 2 additions and 2 deletions
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4
arch/x86/kernel/pci-gart_64.c
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@ -824,10 +824,10 @@ void __init gart_iommu_init(void)
wbinvd(); wbinvd();
/* /*
* Try to workaround a bug (thanks to BenH) * Try to workaround a bug (thanks to BenH):
* Set unmapped entries to a scratch page instead of 0. * Set unmapped entries to a scratch page instead of 0.
* Any prefetches that hit unmapped entries won't get an bus abort * Any prefetches that hit unmapped entries won't get an bus abort
* then. * then. (P2P bridge may be prefetching on DMA reads).
*/ */
scratch = get_zeroed_page(GFP_KERNEL); scratch = get_zeroed_page(GFP_KERNEL);
if (!scratch) if (!scratch)