From c2b84b30b8c8bbccf4d2e32f8a3a70ad09ba9ab8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 30 Jan 2008 13:33:04 +0100
Subject: [PATCH] x86: sanity check APIC timer frequency
Check the APIC timer calibration result for sanity. When the frequency
is out of range, issue a warning and disable the local APIC timer.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/apic_32.c | 13 +++++++++++++
arch/x86/kernel/apic_64.c | 12 ++++++++++++
2 files changed, 25 insertions(+)
diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index cbcf72cde95..20d4dbc42e6 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -470,6 +470,19 @@ void __init setup_boot_APIC_clock(void)
local_apic_timer_verify_ok = 1;
+ /*
+ * Do a sanity check on the APIC calibration result
+ */
+ if (calibration_result < (1000000 / HZ)) {
+ local_irq_enable();
+ printk(KERN_WARNING
+ "APIC frequency too slow, disabling apic timer\n");
+ /* No broadcast on UP ! */
+ if (num_possible_cpus() > 1)
+ setup_APIC_timer();
+ return;
+ }
+
/* We trust the pm timer based calibration */
if (!pm_referenced) {
apic_printk(APIC_VERBOSE, "... verify APIC timer\n");
diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index d1a696673d9..731b48660fc 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -383,6 +383,18 @@ void __init setup_boot_APIC_clock(void)
printk(KERN_INFO "Using local APIC timer interrupts.\n");
calibrate_APIC_clock();
+ /*
+ * Do a sanity check on the APIC calibration result
+ */
+ if (calibration_result < (1000000 / HZ)) {
+ printk(KERN_WARNING
+ "APIC frequency too slow, disabling apic timer\n");
+ /* No broadcast on UP ! */
+ if (num_possible_cpus() > 1)
+ setup_APIC_timer();
+ return;
+ }
+
/*
* If nmi_watchdog is set to IO_APIC, we need the
* PIT/HPET going. Otherwise register lapic as a dummy
--
2.20.1