From: Cyrill Gorcunov <gorcunov@gmail.com>
Date: Wed, 22 Oct 2008 14:00:09 +0000 (+0400)
Subject: x86: do_boot_cpu - check if we have ESR register
X-Git-Tag: v2.6.28-rc1~12^2~9
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=db96b0a0e4158806fcf03945a870f9320e6bac9b;p=linux-2.6-omap-h63xx.git

x86: do_boot_cpu - check if we have ESR register

Impact: fix APIC IRQ irregularities on certain older boxes

We should touch the APIC ESR register if only we have it.

The patch fixes the problem mentioned by Max Kellermann:

	http://lkml.org/lkml/2008/10/17/147

Bisected-by: Max Kellermann <mk@cm4all.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
[ mingo@elte.hu: build fix ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 7ece815ea63..7b109339731 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -893,9 +893,11 @@ do_rest:
 		smpboot_setup_warm_reset_vector(start_ip);
 		/*
 		 * Be paranoid about clearing APIC errors.
-	 	*/
-		apic_write(APIC_ESR, 0);
-		apic_read(APIC_ESR);
+		*/
+		if (APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
+			apic_write(APIC_ESR, 0);
+			apic_read(APIC_ESR);
+		}
 	}
 
 	/*