Commit 96051465 authored by Trent Piepho's avatar Trent Piepho Committed by Kumar Gala
Browse files

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: default avatarTrent Piepho <tpiepho@freescale.com>
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
parent c8f3570b

arch/powerpc/Kconfig

+16 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/mm/fsl_booke_mmu.c

+5 −1
Original line number Diff line number Diff line
@@ -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 {

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