Commit 3c2047cd authored by Rusty Russell's avatar Rusty Russell Committed by Ingo Molnar
Browse files

x86: if we cannot calibrate the TSC, we panic.

The current tsc_init() clears the TSC feature bit if the TSC khz
cannot be calculated, causing us to panic in
arch/x86/kernel/cpu/bugs.c check_config().  We should simply mark it

Frankly, someone should take an axe to this code.  mark_tsc_unstable()
not only marks it unstable, but sets tsc_enabled to 0, which seems
redundant but is actually important here because means it won't be
used by sched_clock() either.  Perhaps a tristate enum "UNUSABLE,
UNSTABLE, OK" would be clearer, and separate mark_tsc_unstable() and
mark_tsc_broken() functions?
Signed-off-by: default avatarRusty Russell <>
Signed-off-by: default avatarIngo Molnar <>
parent 9fc34113
......@@ -392,13 +392,15 @@ void __init tsc_init(void)
int cpu;
if (!cpu_has_tsc)
goto out_no_tsc;
cpu_khz = calculate_cpu_khz();
tsc_khz = cpu_khz;
if (!cpu_khz)
goto out_no_tsc;
if (!cpu_khz) {
mark_tsc_unstable("could not calculate TSC khz");
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,
......@@ -431,9 +433,4 @@ void __init tsc_init(void)
tsc_enabled = 1;
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