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Subject[tip:perf/core] x86, perf: Unmask LVTPC only if we have APIC supported
Commit-ID:  8576e1971663ffdb6139041de97cdd2e1d4791cc
Gitweb: http://git.kernel.org/tip/8576e1971663ffdb6139041de97cdd2e1d4791cc
Author: Cyrill Gorcunov <gorcunov@openvz.org>
AuthorDate: Sat, 13 Mar 2010 11:11:16 +0300
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 13 Mar 2010 13:32:27 +0100

x86, perf: Unmask LVTPC only if we have APIC supported

Ingo reported:

|
| There's a build failure on -tip with the P4 driver, on UP 32-bit, if
| PERF_EVENTS is enabled but UP_APIC is disabled:
|
| arch/x86/built-in.o: In function `p4_pmu_handle_irq':
| perf_event.c:(.text+0xa756): undefined reference to `apic'
| perf_event.c:(.text+0xa76e): undefined reference to `apic'
|

So we have to unmask LVTPC only if we're configured to have one.

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
CC: Lin Ming <ming.m.lin@intel.com>
CC: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20100313081116.GA5179@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/cpu/perf_event_p4.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c
index 381f593..ef861da 100644
--- a/arch/x86/kernel/cpu/perf_event_p4.c
+++ b/arch/x86/kernel/cpu/perf_event_p4.c
@@ -365,8 +365,10 @@ static int p4_pmu_handle_irq(struct pt_regs *regs)
}

if (handled) {
+#ifdef CONFIG_X86_LOCAL_APIC
/* p4 quirk: unmask it again */
apic_write(APIC_LVTPC, apic_read(APIC_LVTPC) & ~APIC_LVT_MASKED);
+#endif
inc_irq_stat(apic_perf_irqs);
}


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