From 060700b571717c997a2ea5e2049b848fa248ee13 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 24 Aug 2008 11:52:06 -0700 Subject: [PATCH] x86: do not enable TSC notifier if we don't need it Impact: crash on non-TSC-equipped CPUs Don't enable the TSC notifier if we *either*: 1. don't have a CPU, or 2. have a CPU with constant TSC. In either of those cases, the notifier is either damaging (1) or useless(2). From: Linus Torvalds Signed-off-by: H. Peter Anvin --- arch/x86/kernel/tsc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 46af7167673..9bed5cae4bd 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -325,6 +325,10 @@ static struct notifier_block time_cpufreq_notifier_block = { static int __init cpufreq_tsc(void) { + if (!cpu_has_tsc) + return 0; + if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) + return 0; cpufreq_register_notifier(&time_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); return 0; -- 2.39.5