Commit 35bb5b1e authored by Andi Kleen's avatar Andi Kleen Committed by Sam Ravnborg

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: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
parent 80ff2624
......@@ -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)
......
......@@ -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
......
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