2 files changed, 21 insertions, 1 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b408e352198c..8782b4b689a7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -730,6 +730,22 @@ config LOWMEM_SIZE
         hex "Maximum low memory size (in bytes)" if LOWMEM_SIZE_BOOL
         default "0x30000000"
 
+config LOWMEM_CAM_NUM_BOOL
+        bool "Set number of CAMs to use to map low memory"
+        depends on ADVANCED_OPTIONS && FSL_BOOKE
+        help
+          This option allows you to set the maximum number of CAM slots that
+          will be used to map low memory.  There are a limited number of slots
+          available and even more limited number that will fit in the L1 MMU.
+          However, using more entries will allow mapping more low memory.  This
+          can be useful in optimizing the layout of kernel virtual memory.
+
+          Say N here unless you know what you are doing.
+
+config LOWMEM_CAM_NUM
+        int "Number of CAMs to use to map low memory" if LOWMEM_CAM_NUM_BOOL
+        default 3
+
 config RELOCATABLE
         bool "Build a relocatable kernel (EXPERIMENTAL)"
         depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM && FSL_BOOKE
diff --git a/arch/powerpc/mm/fsl_booke_mmu.c b/arch/powerpc/mm/fsl_booke_mmu.c
index dfd292748e6e..0b9ba6be49d9 100644
--- a/arch/powerpc/mm/fsl_booke_mmu.c
+++ b/arch/powerpc/mm/fsl_booke_mmu.c
@@ -56,10 +56,14 @@
 
 extern void loadcam_entry(unsigned int index);
 unsigned int tlbcam_index;
-static unsigned long cam[3];
+static unsigned long cam[CONFIG_LOWMEM_CAM_NUM];
 
 #define NUM_TLBCAMS     (16)
 
+#if defined(CONFIG_LOWMEM_CAM_NUM_BOOL) && (CONFIG_LOWMEM_CAM_NUM >= NUM_TLBCAMS)
+#error "LOWMEM_CAM_NUM must be less than NUM_TLBCAMS"
+#endif
+
 struct tlbcam TLBCAM[NUM_TLBCAMS];
 
 struct tlbcamrange {