Ignore RAMTOP for MTRRs
Without RELOCATABLE_RAMSTAGE have WB cache large enough
to cover the greatest ramstage needs, as there is no benefit
of trying to accurately match the actual need. Choose
this to be bottom 16MiB.
With RELOCATABLE_RAMSTAGE write-back cache of low ram is
only useful for bottom 1MiB of RAM as a small part of this gets used
during SMP initialisation before proper MTRR setup.
Change-Id: Icd5f8461f81ed0e671130f1142641a48d1304f30
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/15249
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/src/include/cpu/x86/mtrr.h b/src/include/cpu/x86/mtrr.h
index 4eb4f13..f33a4ac 100644
--- a/src/include/cpu/x86/mtrr.h
+++ b/src/include/cpu/x86/mtrr.h
@@ -91,9 +91,11 @@
(x>>6)|(x>>7)|(x>>8)|((1<<18)-1))
#define _ALIGN_UP_POW2(x) ((x + _POW2_MASK(x)) & ~_POW2_MASK(x))
-#if !defined(CONFIG_RAMTOP) || !CONFIG_RAMTOP
-# error "CONFIG_RAMTOP not configured"
-#endif
+/* At the end of romstage, low ram 0..CACHE_TM_RAMTOP may be set
+ * as write-back cacheable to speed up ramstage decompression.
+ * Note MTRR boundaries, must be power of two.
+ */
+#define CACHE_TMP_RAMTOP (16<<20)
#if ((CONFIG_XIP_ROM_SIZE & (CONFIG_XIP_ROM_SIZE -1)) != 0)
# error "CONFIG_XIP_ROM_SIZE is not a power of 2"
@@ -122,8 +124,4 @@
#define CACHE_ROM_BASE (((1<<20) - (CACHE_ROM_SIZE>>12))<<12)
-#if (CONFIG_RAMTOP & (CONFIG_RAMTOP - 1)) != 0
-# error "CONFIG_RAMTOP must be a power of 2"
-#endif
-
#endif /* CPU_X86_MTRR_H */