From: Joachim Deguara Date: Tue, 24 Apr 2007 11:05:36 +0000 (+0200) Subject: [PATCH] x86-64: make GART PTEs uncacheable X-Git-Tag: v2.6.21~9^2~3 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf6387daf8858bdcb3e123034ca422e8979d73f1;p=linux-2.6 [PATCH] x86-64: make GART PTEs uncacheable This patches fixes the silent data corruption problems being seen using the GART iommu where 4kB of data where incorrect (seen mostly on Nvidia CK804 systems). This fix, to mark the memory regin the GART PTEs reside on as uncacheable, also brings the code in line with the AGP specification. Signed-off-by: Joachim Deguara Signed-off-by: Andi Kleen --- diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c index 2bac8c60ad..0bae862e9a 100644 --- a/arch/x86_64/kernel/pci-gart.c +++ b/arch/x86_64/kernel/pci-gart.c @@ -519,7 +519,11 @@ static __init int init_k8_gatt(struct agp_kern_info *info) gatt_size = (aper_size >> PAGE_SHIFT) * sizeof(u32); gatt = (void *)__get_free_pages(GFP_KERNEL, get_order(gatt_size)); if (!gatt) - panic("Cannot allocate GATT table"); + panic("Cannot allocate GATT table"); + if (change_page_attr_addr((unsigned long)gatt, gatt_size >> PAGE_SHIFT, PAGE_KERNEL_NOCACHE)) + panic("Could not set GART PTEs to uncacheable pages"); + global_flush_tlb(); + memset(gatt, 0, gatt_size); agp_gatt_table = gatt;