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powerpc/fsl-booke: Make CAM entries used for lowmem configurable 

On booke processors, the code that maps low memory only uses up to three
CAM entries, even though there are sixteen and nothing else uses them.

Make this number configurable in the advanced options menu along with max
low memory size.  If one wants 1 GB of lowmem, then it's typically
necessary to have four CAM entries.

Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
This commit is contained in:
Trent Piepho 2008-12-08 19:34:58 -08:00 committed by Kumar Gala
parent c8f3570b7e
commit 96051465fd
2 changed files with 21 additions and 1 deletions
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16
arch/powerpc/Kconfig
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@ -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

6
arch/powerpc/mm/fsl_booke_mmu.c
View File

@ -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 {