Messages in this thread Patch in this message | | | Date | Thu, 10 Dec 2009 17:39:40 +0100 | From | Gernot Hillier <> | Subject | [PATCH] [REMINDER] x86: fix warning for unsynchronized TSCs (was: avoid modifying global flag tsc_unstable in unsychronized) |
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From: Gernot Hillier <gernot.hillier@siemens.com>
This is a small reminder for a patch I sent some weeks ago. It was already confirmed by Alok (see http://article.gmane.org/gmane.linux.kernel/901641). I also decided to give it a better summary. Here's the original description from last mail:
The current behavior of unsynchronized_tsc() prevents the warning for unsychronized TSCs to be printed: tsc_init() calls unsynchronized_tsc() first to check for such problems; if found, mark_tsc_unstable() is called. However, the latter bails out immediately as unsynchronized_ tsc() did already set the global flag tsc_unstable. Thus, the intended warning message "Marking TSC unstable due to TSCs unsynchronized" won't show up.
This patch changes the behavior for unsynchronized_tsc() to only *check* for the quirk condition, but not to modify any global flags. If I'm not mistaken, the only place to *set* the flag shall be mark_tsc_unstable().
Signed-off-by: Gernot Hillier <gernot.hillier@siemens.com> Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com> Reviewed-by: Wolfgang Mauerer <wolfgang.mauerer@siemens.com> Reviewed-by: Alok Kataria <akataria@vmware.com>
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index cd982f4..ffbb786 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -836,10 +836,10 @@ __cpuinit int unsynchronized_tsc(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { /* assume multi socket systems are not synchronized: */ if (num_possible_cpus() > 1) - tsc_unstable = 1; + return 1; } - return tsc_unstable; + return 0; } static void __init init_tsc_clocksource(void)
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