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authorPeter Zijlstra <peterz@infradead.org>2017-04-13 15:56:44 +0300
committerIngo Molnar <mingo@kernel.org>2017-05-15 11:15:14 +0300
commit8309f86cd41e8714526867177facf7a316d9be53 (patch)
treeea2ca294166540ec796bfcdb8c3936aabfd61fa9 /arch/x86/kernel/tsc.c
parent625ed2bf049d5a352c1bcca962d6e133454eaaff (diff)
downloadlinux-8309f86cd41e8714526867177facf7a316d9be53.tar.xz
x86/tsc: Provide 'tsc=unstable' boot parameter
Since the clocksource watchdog will only detect broken TSC after the fact, all TSC based clocks will likely have observed non-continuous values before/when switching away from TSC. Therefore only thing to fully avoid random clock movement when your BIOS randomly mucks with TSC values from SMI handlers is reporting the TSC as unstable at boot. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 714dfba6a1e7..8ab883a4293e 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -374,6 +374,8 @@ static int __init tsc_setup(char *str)
tsc_clocksource_reliable = 1;
if (!strncmp(str, "noirqtime", 9))
no_sched_irq_time = 1;
+ if (!strcmp(str, "unstable"))
+ mark_tsc_unstable("boot parameter");
return 1;
}