From 114c86d82654801fb77c5b2522739559a09997d3 Mon Sep 17 00:00:00 2001 From: Przemyslaw Marczak Date: Wed, 4 Mar 2015 14:01:22 +0100 Subject: [PATCH] arm: relocation: clear .bss section with arch memset if defined For ARM architecture, enable the CONFIG_USE_ARCH_MEMSET/MEMCPY, will highly increase the memset/memcpy performance. This is able thanks to the ARM multiple register instructions. Unfortunatelly the relocation is done without the cache enabled, so it takes some time, but zeroing the BSS memory takes much more longer, especially for the configs with big static buffers. A quick test confirms, that the boot time improvement after using the arch memcpy for relocation has no significant meaning. The same test confirms that enable the memset for zeroing BSS, reduces the boot time. So this patch enables the arch memset for zeroing the BSS after the relocation process. For ARM boards, this can be enabled in board configs by defining: 'CONFIG_USE_ARCH_MEMSET'. This was tested on Trats2. A quick test with trace. Boot time from start to main_loop() entry: - ~1384ms - before this change - ~888ms - after this change Signed-off-by: Przemyslaw Marczak Reviewed-by: Simon Glass Cc: Albert Aribaud Cc: Tom Rini --- arch/arm/lib/crt0.S | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S index 7939cedede..92d37324d3 100644 --- a/arch/arm/lib/crt0.S +++ b/arch/arm/lib/crt0.S @@ -122,14 +122,22 @@ here: movne sp, r0 # endif ldr r0, =__bss_start /* this is auto-relocated! */ - ldr r1, =__bss_end /* this is auto-relocated! */ +#ifdef CONFIG_USE_ARCH_MEMSET + ldr r3, =__bss_end /* this is auto-relocated! */ + mov r1, #0x00000000 /* prepare zero to clear BSS */ + + subs r2, r3, r0 /* r2 = memset len */ + bl memset +#else + ldr r1, =__bss_end /* this is auto-relocated! */ mov r2, #0x00000000 /* prepare zero to clear BSS */ clbss_l:cmp r0, r1 /* while not at end of BSS */ strlo r2, [r0] /* clear 32-bit BSS word */ addlo r0, r0, #4 /* move to next */ blo clbss_l +#endif #if ! defined(CONFIG_SPL_BUILD) bl coloured_LED_init -- 2.39.5