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x86, reboot: Drop redundant write of reboot_mode

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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 <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2012-06-20 21:18:14 -07:00
parent 650513979a
commit 2b1b712f05
1 changed files with 0 additions and 8 deletions
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8
arch/x86/kernel/reboot.c
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@ -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" : :