Don't allow unguarded mappings in PCI-express space. This is resolves
problems with frame buffers having garbage on them due to failing
write merges.
Index: 2.6.21/arch/powerpc/mm/hash_native_64.c
===================================================================
--- 2.6.21.orig/arch/powerpc/mm/hash_native_64.c
+++ 2.6.21/arch/powerpc/mm/hash_native_64.c
@@ -152,6 +152,10 @@ static long native_hpte_insert(unsigned
if (i == HPTES_PER_GROUP)
return -1;
+ /* Workaround for bug 4910: No non-guarded access over IOB */
+ if (pa >= 0x80000000 && pa < 0x100000000)
+ rflags |= _PAGE_GUARDED;
+
hpte_v = hpte_encode_v(va, psize) | vflags | HPTE_V_VALID;
hpte_r = hpte_encode_r(pa, psize) | rflags;
--
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