Subject: [PATCH] make gcc -O1 in fs/reiserfs optional

From: Olaf Hering <[email-masked]>
Date: Tue, 26 Apr 2005 23:10:19 +0200

Jeff,

you added this EXTRA_CFLAGS= during 2.4 development, I think the broken
compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config
option?

Signed-off-by: Olaf Hering <[email-masked]>

Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile
===================================================================
--- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile
+++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile
@@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y)
 reiserfs-objs += xattr_acl.o
 endif
 
-# gcc -O2 (the kernel default)  is overaggressive on ppc32 when many inline
-# functions are used.  This causes the compiler to advance the stack
-# pointer out of the available stack space, corrupting kernel space,
-# and causing a panic. Since this behavior only affects ppc32, this ifeq
-# will work around it. If any other architecture displays this behavior,
-# add it here.
-ifeq ($(CONFIG_PPC32),y)
+ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y)
 EXTRA_CFLAGS := -O1
 endif
 
Index: linux-2.6.12-rc3-olh/fs/Kconfig
===================================================================
--- linux-2.6.12-rc3-olh.orig/fs/Kconfig
+++ linux-2.6.12-rc3-olh/fs/Kconfig
@@ -186,6 +186,18 @@ config REISERFS_FS
 	  If you like it, you can pay us to add new features to it that you
 	  need, buy a support contract, or pay us to port it to another OS.
 
+config REISERFS_CC_REDUCE_OPTIMZE
+	bool "Reduce CC optimization level to workaround compiler bugs"
+	depends on PPC32
+	default n
+	help
+	  gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline
+	  functions are used.  This causes the compiler to advance the stack
+	  pointer out of the available stack space, corrupting kernel space,
+	  and causing a panic. Since this behavior only affects ppc32, this ifeq
+	  will work around it. If any other architecture displays this behavior,
+	  add it here.
+
 config REISERFS_CHECK
 	bool "Enable reiserfs debug mode"
 	depends on REISERFS_FS