powerpc: reserve fixmap entries for early debug

Add a set of entries to the fixmap table to allow usage of known
reserved virtual address space by early debug code.

The address space reserved is the top 128K of the 32-bit address
space. This allows, if required, the use of a BAT to do the mappings.

Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/fixmap.h b/arch/powerpc/include/asm/fixmap.h
index f1f4e23a84e9..5c2c0233175e 100644
--- a/arch/powerpc/include/asm/fixmap.h
+++ b/arch/powerpc/include/asm/fixmap.h
@@ -44,6 +44,9 @@
  */
 enum fixed_addresses {
         FIX_HOLE,
+        /* reserve the top 128K for early debugging purposes */
+        FIX_EARLY_DEBUG_TOP = FIX_HOLE,
+        FIX_EARLY_DEBUG_BASE = FIX_EARLY_DEBUG_TOP+((128*1024)/PAGE_SIZE)-1,
 #ifdef CONFIG_HIGHMEM
         FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
         FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,