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    Subject[tip:x86/reboot] x86, reboot: Drop redundant write of reboot_mode
    Commit-ID:  2b1b712f050eaf0ac576591281446dc960c0afc5
    Gitweb: http://git.kernel.org/tip/2b1b712f050eaf0ac576591281446dc960c0afc5
    Author: H. Peter Anvin <hpa@zytor.com>
    AuthorDate: Wed, 20 Jun 2012 21:18:14 -0700
    Committer: H. Peter Anvin <hpa@zytor.com>
    CommitDate: Wed, 20 Jun 2012 21:18:14 -0700

    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 <hpa@zytor.com>
    ---
    arch/x86/kernel/reboot.c | 8 --------
    1 files changed, 0 insertions(+), 8 deletions(-)

    diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
    index 6ddb9cd..6ef559f 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" : :

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