Re: [PATCH] powerpc 44x: support for 256KB PAGE_SIZE
From: Milton Miller <hidden>
Date: 2008-12-20 22:33:32
On Dec 19, 2008, at 12:39 AM, Yuri Tikhonov wrote:
This patch adds support for 256KB pages on ppc44x-based boards.
Hi. A couple of small comments.
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diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index cd8ff7c..348702c 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig@@ -436,6 +436,14 @@ config PPC_64K_PAGES bool "64k page size" if 44x || PPC_STD_MMU_64 select PPC_HAS_HASH_64K if PPC_STD_MMU_64 +config PPC_256K_PAGES + bool "256k page size" if 44x + depends on !STDBINUTILS + help + ELF standard supports only page sizes up to 64K so you need apatched + binutils in order to use 256K pages. Chose it only if you know what + you are doing. +
Make the page size 256k. As the ELF standard only requires alignment to support page sizes up to 64k, you will need to compile all of your user space applications with a patched binutils. Say N unless you know what you are doing. (The previous text did not describe what the option actually did, and did not emphasize that all of user space had to be compiled).
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diff --git a/arch/powerpc/include/asm/thread_info.hb/arch/powerpc/include/asm/thread_info.h index 9665a26..3c8bbab 100644--- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h@@ -15,8 +15,12 @@ #ifdef CONFIG_PPC64 #define THREAD_SHIFT 14 #else +#ifdef CONFIG_PPC_256K_PAGES +#define THREAD_SHIFT 15 +#else #define THREAD_SHIFT 13 #endif +#endif
Switching to #elif would remove the nested ifdef here.
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#define THREAD_SIZE (1 << THREAD_SHIFT)diff --git a/arch/powerpc/kernel/head_booke.hb/arch/powerpc/kernel/head_booke.h index fce2df9..bc6a26c 100644--- a/arch/powerpc/kernel/head_booke.h +++ b/arch/powerpc/kernel/head_booke.h@@ -10,6 +10,14 @@ mtspr SPRN_IVOR##vector_number,r26; \ sync +#ifndef CONFIG_PPC_256K_PAGES
This if should be on THREAD_SIZE or THREAD_SHIFT, not the option that causes it to be large.
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+#define ALLOC_STACK_FRAME(reg, val) addi reg,reg,val +#else +#define ALLOC_STACK_FRAME(reg, val) \ + addis reg,reg,val@ha; \ + addi reg,reg,val@l +#endif + #define NORMAL_EXCEPTION_PROLOG \ mtspr SPRN_SPRG0,r10; /* save two registers to work with */\ mtspr SPRN_SPRG1,r11; \@@ -20,7 +28,7 @@ beq 1f; \ mfspr r1,SPRN_SPRG3; /* if from user, start at top of */\ lwz r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack */\ - addi r1,r1,THREAD_SIZE; \ + ALLOC_STACK_FRAME(r1, THREAD_SIZE); \ 1: subi r1,r1,INT_FRAME_SIZE; /* Allocate an exception frame */\ mr r11,r1; \ stw r10,_CCR(r11); /* save various registers */\diff --git a/init/Kconfig b/init/Kconfig index f763762..96229b9 100644 --- a/init/Kconfig +++ b/init/Kconfig@@ -635,6 +635,16 @@ config ELF_CORE help Enable support for generating core dumps. Disabling saves about 4k. +config STDBINUTILS + bool "Using standard binutils" if EMBEDDED + depends on 44x + default y + help + Turning this option off allows you to select 256KB PAGE_SIZE on44x. + Note, that kernel will be able to run only those applications, + which had been compiled using the patched binutils (ELF standard + supports only page sizes up to 64K). +
The config variable 44x is pretty nondescript for a global config file. If you leave it here, I would suggest making it depend on PPC && 44x so that other people don't have to wonder what 44x means. I didn't look if there was a better place to put this option, somewhere architecture specific might be better (eg after selecting the 44x cpu type).
config PCSPKR_PLATFORM bool "Enable PC-Speaker support" if EMBEDDED depends on ALPHA || X86 || MIPS || PPC_PREP || PPC_CHRP || PPC_PSERIES
thanks, milton