linux-kernel - [PATCH] x86,perf: Unmask LVTPC only if we have APIC supported

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Message-ID: <20100313081116.GA5179@lenovo>
Date:	Sat, 13 Mar 2010 11:11:16 +0300
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Lin Ming <ming.m.lin@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] 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@...e.hu>
CC: Lin Ming <ming.m.lin@...el.com>
CC: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
---
 arch/x86/kernel/cpu/perf_event_p4.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c
+++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
@@ -365,8 +365,10 @@ static int p4_pmu_handle_irq(struct pt_r
 	}
 
 	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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