x86: PAT infrastructure patch
Sets up pat_init() infrastructure.
PAT MSR has following setting.
PAT
|PCD
||PWT
|||
000 WB _PAGE_CACHE_WB
001 WC _PAGE_CACHE_WC
010 UC- _PAGE_CACHE_UC_MINUS
011 UC _PAGE_CACHE_UC
We are effectively changing WT from boot time setting to WC.
UC_MINUS is used to provide backward compatibility to existing /dev/mem
users(X).
reserve_memtype and free_memtype are new interfaces for maintaining alias-free
mapping. It is currently implemented in a simple way with a linked list and
not optimized. reserve and free tracks the effective memory type, as a result
of PAT and MTRR setting rather than what is actually requested in PAT.
pat_init piggy backs on mtrr_init as the rules for setting both pat and mtrr
are same.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fd27048..5b46756 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1009,6 +1009,21 @@
See <file:Documentation/mtrr.txt> for more information.
+config X86_PAT
+ def_bool y
+ prompt "x86 PAT support"
+ depends on MTRR && NONPROMISC_DEVMEM
+ help
+ Use PAT attributes to setup page level cache control.
+ ---help---
+ PATs are the modern equivalents of MTRRs and are much more
+ flexible than MTRRs.
+
+ Say N here if you see bootup problems (boot crash, boot hang,
+ spontaneous reboots) or a non-working Xorg.
+
+ If unsure, say Y.
+
config EFI
def_bool n
prompt "EFI runtime service support"
