From 2b84008ed9a5d14b519834d6d85c4955fa326684 Mon Sep 17 00:00:00 2001 From: Himanshu Sahdev aka CunningLearner Date: Sun, 8 Sep 2019 12:29:27 +0530 Subject: [PATCH] arch/x86/bootblock_crt0.S: Leverage eax in protected mode entry Leverage already used eax register in bootblock_protected_mode_entry. Avoid another register ebx just for preserving eax value as it is not needed and is not used at all after moving the value into mm0. Allow EBX to be preserved for other usage. Change-Id: Ia668b78f2f97cf026692f1fe63ff8a382a162474 Signed-off-by: Himanshu Sahdev Reviewed-on: https://review.coreboot.org/c/coreboot/+/35292 Reviewed-by: Arthur Heymans Reviewed-by: Aaron Durbin Reviewed-by: Furquan Shaikh Tested-by: build bot (Jenkins) --- src/arch/x86/bootblock_crt0.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/arch/x86/bootblock_crt0.S b/src/arch/x86/bootblock_crt0.S index c07363d856..3cb57e058c 100644 --- a/src/arch/x86/bootblock_crt0.S +++ b/src/arch/x86/bootblock_crt0.S @@ -47,11 +47,10 @@ bootblock_protected_mode_entry: /* MMX registers required here */ /* BIST result in eax */ - movl %eax, %ebx + movd %eax, %mm0 /* Get an early timestamp */ rdtsc - movd %ebx, %mm0 movd %eax, %mm1 movd %edx, %mm2 #endif