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Commit 14d98cad authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[PATCH] x86_64: Add option to disable timer check 



This works around the too fast timer seen on some ATI boards.

I don't feel confident enough about it yet to enable it by default, but give
users the option.

Patch and debugging from Christopher Allen Wing <wingc@engin.umich.edu>, with
minor tweaks (renamed the option and documented it)

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 607a1685

Documentation/x86_64/boot-options.txt

+3 −0
Original line number Diff line number Diff line
@@ -25,6 +25,9 @@ APICs 


   noapictimer	 Don't set up the APIC timer



   no_timer_check Don't check the IO-APIC timer. This can work around

		 problems with incorrect timer initialization on some boards.



Early Console



   syntax: earlyprintk=vga

arch/x86_64/kernel/io_apic.c

+10 −1
Original line number Diff line number Diff line
@@ -42,6 +42,8 @@ 


int sis_apic_bug; /* not actually supported, dummy for compile */



static int no_timer_check;



static DEFINE_SPINLOCK(ioapic_lock);



/*
@@ -1601,7 +1603,7 @@ static inline void check_timer(void) 
		 * Ok, does IRQ0 through the IOAPIC work?

		 */

		unmask_IO_APIC_irq(0);

		if (timer_irq_works()) {

		if (!no_timer_check && timer_irq_works()) {

			nmi_watchdog_default();

			if (nmi_watchdog == NMI_IO_APIC) {

				disable_8259A_irq(0);
@@ -1671,6 +1673,13 @@ static inline void check_timer(void) 
	panic("IO-APIC + timer doesn't work! Try using the 'noapic' kernel parameter\n");

}



static int __init notimercheck(char *s)

{

	no_timer_check = 1;

	return 1;

}

__setup("no_timer_check", notimercheck);



/*

 *

 * IRQ's that are handled by the PIC in the MPS IOAPIC case.