From: Rusty Russell Date: Tue, 4 Mar 2008 12:07:50 +0000 (+1100) Subject: x86: if we cannot calibrate the TSC, we panic. X-Git-Tag: v2.6.26-rc1~1154^2~491 X-Git-Url: http://pilppa.org/gitweb/?a=commitdiff_plain;h=3c2047cd32b1a8c782d7efab72707e7daa251625;p=linux-2.6-omap-h63xx.git 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 unstable. 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: Rusty Russell Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index c2241e04ea5..68657d8526f 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -392,13 +392,15 @@ void __init tsc_init(void) int cpu; if (!cpu_has_tsc) - goto out_no_tsc; + return; 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"); + return; + } printk("Detected %lu.%03lu MHz processor.\n", (unsigned long)cpu_khz / 1000, @@ -431,9 +433,4 @@ void __init tsc_init(void) tsc_enabled = 1; clocksource_register(&clocksource_tsc); - - return; - -out_no_tsc: - setup_clear_cpu_cap(X86_FEATURE_TSC); }