The patch titled
paravirt: skip timer works
has been added to the -mm tree. Its filename is
paravirt-skip-timer-works.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: paravirt: skip timer works
From: Zachary Amsden <zach@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
Documentation/kernel-parameters.txt | 7 +++++--
arch/i386/kernel/io_apic.c | 16 ++++++++++++++--
2 files changed, 19 insertions(+), 4 deletions(-)
diff -puN Documentation/kernel-parameters.txt~paravirt-skip-timer-works Documentation/kernel-parameters.txt
--- a/Documentation/kernel-parameters.txt~paravirt-skip-timer-works
+++ a/Documentation/kernel-parameters.txt
@@ -599,8 +599,6 @@ 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
@@ -1056,9 +1054,14 @@ 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.
+ noirqtest [IA-32,APIC] Disables the code which tests for broken
+ timer IRQ sources.
+
noisapnp [ISAPNP] Disables ISA PnP code.
noinitrd [RAM] Tells the kernel not to load any configured
diff -puN arch/i386/kernel/io_apic.c~paravirt-skip-timer-works arch/i386/kernel/io_apic.c
--- a/arch/i386/kernel/io_apic.c~paravirt-skip-timer-works
+++ a/arch/i386/kernel/io_apic.c
@@ -1864,6 +1864,15 @@ static void __init setup_ioapic_ids_from
static void __init setup_ioapic_ids_from_mpc(void) { }
#endif
+int timer_irq_really_works __initdata;
+int __init irqtest_disable(char *str)
+{
+ timer_irq_really_works = 1;
+ return 1;
+}
+
+__setup("noirqtest", irqtest_disable);
+
/*
* 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:
@@ -1872,10 +1881,13 @@ 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 (timer_irq_really_works)
+ return 1;
+
local_irq_enable();
/* Let ten ticks pass... */
mdelay((10 * 1000) / HZ);
@@ -2146,7 +2158,7 @@ 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;
_
Patches currently in -mm which might be from zach@xxxxxxxxxx are
fix-potential-interrupts-during-alternative-patching-was.patch
i386-pda-basic-definitions-for-i386-pda.patch
i386-pda-initialize-the-per-cpu-data-area.patch
i386-pda-use-%gs-as-the-pda-base-segment-in-the-kernel.patch
i386-pda-fix-places-where-using-%gs-changes-the-usermode-abi.patch
i386-pda-update-sys_vm86-to-cope-with-changed-pt_regs-and-%gs-usage.patch
i386-pda-implement-smp_processor_id-with-the-pda.patch
i386-pda-implement-current-with-the-pda.patch
paravirt-skip-timer-works.patch
paravirt-skip-timer-works-tidy.patch
paravirt-interrupts-subarch-cleanup.patch
paravirt-fix-missing-pte-update.patch
paravirt-fix-bad-mmu-names.patch
paravirt-mmu-header-movement.patch
-
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