From 2b1b712f050eaf0ac576591281446dc960c0afc5 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 20 Jun 2012 21:18:14 -0700 Subject: [PATCH] x86, reboot: Drop redundant write of reboot_mode We write reboot_mode to BIOS location 0x472 in native_machine_emergency_restart() (reboot.c:542) already, there is no need to then write it again in machine_real_restart(). This means nothing gets written there for MRR_APM, but the APM call is a poweroff call and doesn't use this memory location. Link: http://lkml.kernel.org/n/tip-3i0pfh44c1e3jv5lab0cf7sc@git.kernel.org Signed-off-by: H. Peter Anvin --- arch/x86/kernel/reboot.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 6ddb9cd0ced0..6ef559f09acd 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -179,14 +179,6 @@ void __noreturn machine_real_restart(unsigned int type) write_cr3(real_mode_header->trampoline_pgd); #endif - /* - * Write 0x1234 to absolute memory location 0x472. The BIOS reads - * this on booting to tell it to "Bypass memory test (also warm - * boot)". This seems like a fairly standard thing that gets set by - * REBOOT.COM programs, and the previous reset routine did this - * too. */ - *((unsigned short *)0x472) = reboot_mode; - /* Jump to the identity-mapped low memory code */ #ifdef CONFIG_X86_32 asm volatile("jmpl *%0" : : -- 2.34.1