x86, reboot: Drop redundant write of reboot_mode (2b1b712f) · Commits · 戴 / test

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

+0 −8

Original line number	Diff line number	Diff line
		@@ -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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