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Commit e6c4dc6c authored by Willy Tarreau's avatar Willy Tarreau Committed by Ingo Molnar
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x86: GEODE add the "mfgptfix" boot time option to fix MFGPT timers 



The new "mfgptfix" boot command line option may be usd to fix MFGPT
timers on AMD Geode platforms when the BIOS has incorrectly applied
a workaround. TinyBIOS version 0.98 is known to be affected, 0.99
fixes the problem by letting the user disable the workaround.

Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 45078cb5

Documentation/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -1092,6 +1092,11 @@ and is between 256 and 4096 characters. It is defined in the file 
			Multi-Function General Purpose Timers on AMD Geode

			platforms.



	mfgptfix	[X86-32] Fix MFGPT timers on AMD Geode platforms when

			the BIOS has incorrectly applied a workaround. TinyBIOS

			version 0.98 is known to be affected, 0.99 fixes the

			problem by letting the user disable the workaround.



	mga=		[HW,DRM]



	mousedev.tap_time=

arch/x86/kernel/mfgpt_32.c

+15 −0
Original line number Diff line number Diff line
@@ -63,6 +63,21 @@ static int __init mfgpt_disable(char *s) 
}

__setup("nomfgpt", mfgpt_disable);



/* Reset the MFGPT timers. This is required by some broken BIOSes which already

 * do the same and leave the system in an unstable state. TinyBIOS 0.98 is

 * affected at least (0.99 is OK with MFGPT workaround left to off).

 */

static int __init mfgpt_fix(char *s)

{

	u32 val, dummy;



	/* The following udocumented bit resets the MFGPT timers */

	val = 0xFF; dummy = 0;

	wrmsr(0x5140002B, val, dummy);

	return 1;

}

__setup("mfgptfix", mfgpt_fix);



/*

 * Check whether any MFGPTs are available for the kernel to use.  In most

 * cases, firmware that uses AMD's VSA code will claim all timers during