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/include/asm-x86/pat.h b/include/asm-x86/pat.h
new file mode 100644
index 0000000..8b822b5
--- /dev/null
+++ b/include/asm-x86/pat.h
@@ -0,0 +1,16 @@
+
+#ifndef _ASM_PAT_H
+#define _ASM_PAT_H 1
+
+#include <linux/types.h>
+
+extern int pat_wc_enabled;
+
+extern void pat_init(void);
+
+extern int reserve_memtype(u64 start, u64 end,
+ unsigned long req_type, unsigned long *ret_type);
+extern int free_memtype(u64 start, u64 end);
+
+#endif
+