From: Ian Campbell <ijc@hellion.org.uk>
Date: Wed, 30 Jan 2008 12:33:27 +0000 (+0100)
Subject: x86_32: remove unnecessary use of %ebx as the boot cpu flag
X-Git-Tag: v2.6.25-rc1~1143^2~202
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=503595010f2024b236fd2636a7318fe64c794d6c;p=linux-2.6

x86_32: remove unnecessary use of %ebx as the boot cpu flag

Currently in head_32.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@xmission.com>
Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Mika Penttilä <mika.penttila@kolumbus.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index f409fe2a52..7b9b2566b7 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -199,7 +199,6 @@ default_entry:
 	addl $0x67, %eax			/* 0x67 == _PAGE_TABLE */
 	movl %eax, 4092(%edx)
 
-	xorl %ebx,%ebx				/* This is the boot CPU (BSP) */
 	jmp 3f
 /*
  * Non-boot CPU entry point; entered from trampoline.S
@@ -268,10 +267,6 @@ ENTRY(startup_32_smp)
 	wrmsr
 
 6:
-	/* This is a secondary processor (AP) */
-	xorl %ebx,%ebx
-	incl %ebx
-
 #endif /* CONFIG_SMP */
 3:
 
@@ -297,7 +292,7 @@ ENTRY(startup_32_smp)
 	popfl
 
 #ifdef CONFIG_SMP
-	andl %ebx,%ebx
+	cmpb $0, ready
 	jz  1f				/* Initial CPU cleans BSS */
 	jmp checkCPUtype
 1: