[PATCH 3/3] x86, NMI: knob to disable using NMI IPIs to stop cpus

Don Zickus
2011-10-11T15:26:14Z

Some machines may exhibit problems using the NMI to stop other cpus.
This knob just allows one to revert back to the original behaviour to help
diagnose the problem.

Signed-off-by: Don Zickus <dzickus@redhat.com>
---
Documentation/kernel-parameters.txt | 4 ++++
arch/x86/kernel/smp.c | 8 ++++++++
2 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6ca1f5c..dab6439 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1761,6 +1761,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).

+ nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
+ shutdown the other cpus. Instead use the REBOOT_VECTOR
+ irq.
+
nopat [X86] Disable PAT (page attribute table extension of
pagetables) support.

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index f54e07a..cc8026a 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -283,6 +283,14 @@ void smp_call_function_single_interrupt(struct pt_regs *regs)
irq_exit();
}

+int __init nonmi_ipi_setup(char *str)
+{
+ native_smp_disable_nmi_ipi();
+ return 1;
+}
+
+__setup("nonmi_ipi", nonmi_ipi_setup);
+
struct smp_ops smp_ops = {
.smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
.smp_prepare_cpus = native_smp_prepare_cpus,
--
1.7.6.4