From: Andi Kleen <ak@suse.de>
Date: Sat, 9 Dec 2006 20:33:36 +0000 (+0100)
Subject: [PATCH] x86: Work around gcc 4.2 over aggressive optimizer
X-Git-Tag: v2.6.20-rc1~34^2~19^2~3
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1bac3b383a93a4a920ffc57441eb133c78567fbd;p=linux-2.6

[PATCH] x86: Work around gcc 4.2 over aggressive optimizer

The new PDA code uses a dummy _proxy_pda variable to describe
memory references to the PDA. It is never referenced
in inline assembly, but exists as input/output arguments.
gcc 4.2 in some cases can CSE references to this which causes
unresolved symbols.  Define it to zero to avoid this.

Signed-off-by: Andi Kleen <ak@suse.de>
---

diff --git a/arch/i386/kernel/vmlinux.lds.S b/arch/i386/kernel/vmlinux.lds.S
index 16d3c7133a..a53c8b1854 100644
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -26,6 +26,7 @@ OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
 OUTPUT_ARCH(i386)
 ENTRY(phys_startup_32)
 jiffies = jiffies_64;
+_proxy_pda = 0;
 
 PHDRS {
 	text PT_LOAD FLAGS(5);	/* R_E */
diff --git a/arch/x86_64/kernel/vmlinux.lds.S b/arch/x86_64/kernel/vmlinux.lds.S
index 6c417788c5..514be5dd23 100644
--- a/arch/x86_64/kernel/vmlinux.lds.S
+++ b/arch/x86_64/kernel/vmlinux.lds.S
@@ -13,6 +13,7 @@ OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
 OUTPUT_ARCH(i386:x86-64)
 ENTRY(phys_startup_64)
 jiffies_64 = jiffies;
+_proxy_pda = 0;
 PHDRS {
 	text PT_LOAD FLAGS(5);	/* R_E */
 	data PT_LOAD FLAGS(7);	/* RWE */