linux-kernel - [RFC PATCH] apic: drop useless apic

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Message-ID: <1492594109-13497-1-git-send-email-caoj.fnst@cn.fujitsu.com>
Date:   Wed, 19 Apr 2017 17:28:29 +0800
From:   Cao jin <caoj.fnst@...fujitsu.com>
To:     <linux-kernel@...r.kernel.org>
CC:     <tglx@...utronix.de>, <mingo@...hat.com>, <hpa@...or.com>,
        <x86@...nel.org>
Subject: [RFC PATCH] apic: drop useless apic_read

APIC ESR register reading doesn't clear its content.

Signed-off-by: Cao jin <caoj.fnst@...fujitsu.com>
---
It is also a question represented by a patch: Intel developer manual
doesn't say reading will clear it content, so why read it here?

 arch/x86/kernel/apic/apic.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 8ccb7ef..1742324 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1065,7 +1065,6 @@ void clear_local_APIC(void)
 		if (maxlvt > 3)
 			/* Clear ESR due to Pentium errata 3AP and 11AP */
 			apic_write(APIC_ESR, 0);
-		apic_read(APIC_ESR);
 	}
 }
 
-- 
2.1.0