* Andi Kleen (ak at muc.de) wrote:
> On Mon, Oct 30, 2006 at 12:54:55PM -0800, Zachary Amsden wrote:
> > Andi Kleen wrote:
> > >no_timer_check. But it's only there on x86-64 in mainline - although there
> > >were some patches to add it to i386 too.
> > >
> >
> > I can rename to match the x86-64 name.
>
> I will do that in my tree.
Looks like this one might have been lost. Here's the renamed version
(it's against 2.6.19-rc5-mm2, which should have your tree in it).
thanks,
-chris
--
From: Zachary Amsden <zach at vmware.com>
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 at vmware.com>
[chrisw: use no_timer_check to bring inline with x86_64 as per Andi's request]
Signed-off-by: Chris Wright <chrisw at sous-sol.org>
===================================================================
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -610,8 +610,6 @@ and is between 256 and 4096 characters.
hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
- noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
-
i8042.direct [HW] Put keyboard port into non-translated mode
i8042.dumbkbd [HW] Pretend that controller can only read data from
keyboard and cannot control its state
@@ -1081,8 +1079,13 @@ and is between 256 and 4096 characters.
in certain environments such as networked servers or
real-time systems.
+ noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
+
noirqdebug [IA-32] Disables the code which attempts to detect and
disable unhandled interrupt sources.
+
+ no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
+ broken timer IRQ sources.
noisapnp [ISAPNP] Disables ISA PnP code.
===================================================================
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -1931,6 +1931,15 @@ static void __init setup_ioapic_ids_from
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:
@@ -1939,9 +1948,12 @@ static void __init setup_ioapic_ids_from
* - 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... */
@@ -2219,7 +2231,7 @@ 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;
