[PATCH] CONFIG_FRAME_POINTER

From 2.4, this adds a CONFIG_ option to disable
the usage of -fomit-frame-pointer

Makefile

@@ -168,7 +168,10 @@ NOSTDINC_FLAGS  = -nostdinc -iwithprefix include
 
 CPPFLAGS	:= -D__KERNEL__ -Iinclude
 CFLAGS 		:= $(CPPFLAGS) -Wall -Wstrict-prototypes -Wno-trigraphs -O2 \
-	  	   -fomit-frame-pointer -fno-strict-aliasing -fno-common
+	  	   -fno-strict-aliasing -fno-common
+ifndef CONFIG_FRAME_POINTER
+CFLAGS		+= -fomit-frame-pointer
+endif
 AFLAGS		:= -D__ASSEMBLY__ $(CPPFLAGS)
 
 export	VERSION PATCHLEVEL SUBLEVEL EXTRAVERSION KERNELRELEASE ARCH \

arch/i386/Kconfig

@@ -1618,6 +1618,14 @@ config DEBUG_SPINLOCK_SLEEP
 	  If you say Y here, various routines which may sleep will become very
 	  noisy if they are called with a spinlock held.	
 
+config FRAME_POINTER
+	bool "Compile the kernel with frame pointers"
+	help
+	  If you say Y here the resulting kernel image will be slightly larger
+	  and slower, but it will give very useful debugging information.
+	  If you don't debug the kernel, you can say N, but we may not be able
+	  to solve problems without frame pointers.
+
 config X86_EXTRA_IRQS
 	bool
 	depends on X86_LOCAL_APIC

arch/i386/kernel/semaphore.c

@@ -191,6 +191,10 @@ asm(
 ".align 4\n"
 ".globl __down_failed\n"
 "__down_failed:\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"pushl %ebp\n\t"
+	"movl  %esp,%ebp\n\t"
+#endif
 	"pushl %eax\n\t"
 	"pushl %edx\n\t"
 	"pushl %ecx\n\t"
@@ -198,6 +202,10 @@ asm(
 	"popl %ecx\n\t"
 	"popl %edx\n\t"
 	"popl %eax\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"movl %ebp,%esp\n\t"
+	"popl %ebp\n\t"
+#endif
 	"ret"
 );
 
@@ -206,11 +214,19 @@ asm(
 ".align 4\n"
 ".globl __down_failed_interruptible\n"
 "__down_failed_interruptible:\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"pushl %ebp\n\t"
+	"movl  %esp,%ebp\n\t"
+#endif
 	"pushl %edx\n\t"
 	"pushl %ecx\n\t"
 	"call __down_interruptible\n\t"
 	"popl %ecx\n\t"
 	"popl %edx\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"movl %ebp,%esp\n\t"
+	"popl %ebp\n\t"
+#endif
 	"ret"
 );
 
@@ -219,11 +235,19 @@ asm(
 ".align 4\n"
 ".globl __down_failed_trylock\n"
 "__down_failed_trylock:\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"pushl %ebp\n\t"
+	"movl  %esp,%ebp\n\t"
+#endif
 	"pushl %edx\n\t"
 	"pushl %ecx\n\t"
 	"call __down_trylock\n\t"
 	"popl %ecx\n\t"
 	"popl %edx\n\t"
+#if defined(CONFIG_FRAME_POINTER)
+	"movl %ebp,%esp\n\t"
+	"popl %ebp\n\t"
+#endif
 	"ret"
 );