diff options
| author | Zachary Amsden <zach@vmware.com> | 2006-12-07 02:14:09 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:09 +0100 |
| commit | 8542b200cbe5609edd7aae0c304c091a1c290452 (patch) | |
| tree | 7b8a51fa34639c0e7a73a12c9cc2360b8c6d2efc /arch/i386 | |
| parent | 8ecb8950695e907ed25acffec9e98c6806e311c8 (diff) | |
[PATCH] paravirt: Add option to allow skipping the timer check
Add a way to disable the timer IRQ routing check via a boot option. The
VMI timer code uses this to avoid triggering the pester Mingo code, which
probes for some very unusual and broken motherboard routings. It fires
100% of the time when using a paravirtual delay mechanism instead of using
a realtime delay, since there is no elapsed real time, and the 4 timer IRQs
have not yet been delivered.
In addition, it is entirely possible, though improbable, that this bug
could surface on real hardware which picks a particularly bad time to enter
SMM mode, causing a long latency during one of the timer IRQs.
While here, make check_timer be __init.
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
[chrisw: use no_timer_check to bring inline with x86_64 as per Andi's request]
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Diffstat (limited to 'arch/i386')
| -rw-r--r-- | arch/i386/kernel/io_apic.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c index e33b7a845299..993150f206ed 100644 --- a/arch/i386/kernel/io_apic.c +++ b/arch/i386/kernel/io_apic.c @@ -1932,6 +1932,15 @@ static void __init setup_ioapic_ids_from_mpc(void) static void __init setup_ioapic_ids_from_mpc(void) { } #endif +static int no_timer_check __initdata; + +static int __init notimercheck(char *s) +{ + no_timer_check = 1; + return 1; +} +__setup("no_timer_check", notimercheck); + /* * There is a nasty bug in some older SMP boards, their mptable lies * about the timer IRQ. We do the following to work around the situation: @@ -1940,10 +1949,13 @@ static void __init setup_ioapic_ids_from_mpc(void) { } * - if this function detects that timer IRQs are defunct, then we fall * back to ISA timer IRQs */ -static int __init timer_irq_works(void) +int __init timer_irq_works(void) { unsigned long t1 = jiffies; + if (no_timer_check) + return 1; + local_irq_enable(); /* Let ten ticks pass... */ mdelay((10 * 1000) / HZ); @@ -2214,7 +2226,7 @@ int timer_uses_ioapic_pin_0; * is so screwy. Thanks to Brian Perkins for testing/hacking this beast * fanatically on his truly buggy board. */ -static inline void check_timer(void) +static inline void __init check_timer(void) { int apic1, pin1, apic2, pin2; int vector; |