From 35bb5b1e0e84cfa1a8906f7e6a77f391ff315791 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Fri, 22 Feb 2008 15:15:03 +0100 Subject: Add option to enable -Wframe-larger-than= on gcc 4.4 Add option to enable -Wframe-larger-than= on gcc 4.4 gcc mainline (upcoming 4.4) added a new -Wframe-larger-than=... option to warn at build time about too large stack frames. Add a config option to enable this warning, since this very useful for the kernel. I choose (somewhat arbitarily) 2048 as default warning threshold for 64bit and 1024 as default for 32bit architectures. With some research and fixing all the code for smaller values these defaults should be probably lowered. With the default allyesconfigs have some new warnings, but I think that is all code that should be just fixed. At some point (when gcc 4.4 is released and widely used) this should obsolete make checkstack Signed-off-by: Andi Kleen Signed-off-by: Sam Ravnborg --- Makefile | 4 ++++ lib/Kconfig.debug | 11 +++++++++++ 2 files changed, 15 insertions(+) diff --git a/Makefile b/Makefile index 6ae7fd4475b..c6d331ba140 100644 --- a/Makefile +++ b/Makefile @@ -507,6 +507,10 @@ else KBUILD_CFLAGS += -O2 endif +ifneq (CONFIG_FRAME_WARN,0) +KBUILD_CFLAGS += $(call cc-option,-Wframe-larger-than=${CONFIG_FRAME_WARN}) +endif + # Force gcc to behave correct even for buggy distributions # Arch Makefiles may override this setting KBUILD_CFLAGS += $(call cc-option, -fno-stack-protector) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 623ef24c238..754cc0027f2 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -25,6 +25,17 @@ config ENABLE_MUST_CHECK suppress the "warning: ignoring return value of 'foo', declared with attribute warn_unused_result" messages. +config FRAME_WARN + int "Warn for stack frames larger than (needs gcc 4.4)" + range 0 8192 + default 1024 if !64BIT + default 2048 if 64BIT + help + Tell gcc to warn at build time for stack frames larger than this. + Setting this too low will cause a lot of warnings. + Setting it to 0 disables the warning. + Requires gcc 4.4 + config MAGIC_SYSRQ bool "Magic SysRq key" depends on !UML -- cgit v1.2.3-18-g5258