[patch 27/59] x86: Work around gcc 4.2 over aggressive optimizer

Chris Wright
2007-02-03T02:52:00Z

[-- Attachment #1: x86-work-around-gcc-4.2-over-aggressive-optimizer.patch --]
[-- Type: text/plain, Size: 1262 bytes --]

-stable review patch. If anyone has any objections, please let us know.
------------------

From: Andi Kleen <ak@suse.de>

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>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
arch/i386/kernel/vmlinux.lds.S | 1 +
arch/x86_64/kernel/vmlinux.lds.S | 1 +
2 files changed, 2 insertions(+)

--- linux-2.6.19.2.orig/arch/i386/kernel/vmlinux.lds.S
+++ linux-2.6.19.2/arch/i386/kernel/vmlinux.lds.S
@@ -13,6 +13,7 @@ OUTPUT_FORMAT("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 */
--- linux-2.6.19.2.orig/arch/x86_64/kernel/vmlinux.lds.S
+++ linux-2.6.19.2/arch/x86_64/kernel/vmlinux.lds.S
@@ -13,6 +13,7 @@ OUTPUT_FORMAT("elf64-x86-64", "elf64-x86
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 */

--