linux-kernel - [PATCH 02/12] i386 head.S: Remove unnecessary use of %ebx as the boot cpu flag

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Message-ID: <m14pmx6ewk.fsf_-_@ebiederm.dsl.xmission.com>
Date:	Mon, 30 Apr 2007 09:49:31 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Andi Kleen <ak@...e.de>
Cc:	virtualization <virtualization@...ts.linux-foundation.org>,
	<linux-kernel@...r.kernel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Dave Jones <davej@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: [PATCH 02/12] i386 head.S: Remove unnecessary use of %ebx as the boot cpu flag


Currently in head.S there are two ways we test to see if we
are the boot cpu.  By looking at %ebx and by looking at the
static variable ready.  When changing things around I have
found that it gets tricky to preserve %ebx.  So this
patch just switches head.S over to the more reliable
test of always using ready.

Hopefully later we can kill these tests entirely.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 arch/i386/kernel/head.S |    7 +------
 1 files changed, 1 insertions(+), 6 deletions(-)

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index 9b10af6..aa9e28e 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -157,7 +157,6 @@ page_pde_offset = (__PAGE_OFFSET >> 20);
 	jb 10b
 	movl %edi,(init_pg_tables_end - __PAGE_OFFSET)
 
-	xorl %ebx,%ebx				/* This is the boot CPU (BSP) */
 	jmp 3f
 /*
  * Non-boot CPU entry point; entered from trampoline.S
@@ -228,10 +227,6 @@ ENTRY(startup_32_smp)
 	wrmsr
 
 6:
-	/* This is a secondary processor (AP) */
-	xorl %ebx,%ebx
-	incl %ebx
-
 #endif /* CONFIG_SMP */
 3:
 
@@ -257,7 +252,7 @@ ENTRY(startup_32_smp)
 	popfl
 
 #ifdef CONFIG_SMP
-	andl %ebx,%ebx
+	cmpb $0, ready
 	jz  1f				/* Initial CPU cleans BSS */
 	jmp checkCPUtype
 1:
-- 
1.5.1.1.181.g2de0

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