linux/kernel/gcov/Makefile

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ccflags-y := -DSRCTREE='"$(srctree)"' -DOBJTREE='"$(objtree)"'
gcov: add gcov profiling infrastructure Enable the use of GCC's coverage testing tool gcov [1] with the Linux kernel. gcov may be useful for: * debugging (has this code been reached at all?) * test improvement (how do I change my test to cover these lines?) * minimizing kernel configurations (do I need this option if the associated code is never run?) The profiling patch incorporates the following changes: * change kbuild to include profiling flags * provide functions needed by profiling code * present profiling data as files in debugfs Note that on some architectures, enabling gcc's profiling option "-fprofile-arcs" for the entire kernel may trigger compile/link/ run-time problems, some of which are caused by toolchain bugs and others which require adjustment of architecture code. For this reason profiling the entire kernel is initially restricted to those architectures for which it is known to work without changes. This restriction can be lifted once an architecture has been tested and found compatible with gcc's profiling. Profiling of single files or directories is still available on all platforms (see config help text). [1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Li Wei <W.Li@Sun.COM> Cc: Michael Ellerman <michaele@au1.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com> Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: WANG Cong <xiyou.wangcong@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-18 07:28:08 +08:00
# if-lt
# Usage VAR := $(call if-lt, $(a), $(b))
# Returns 1 if (a < b)
if-lt = $(shell [ $(1) -lt $(2) ] && echo 1)
ifeq ($(CONFIG_GCOV_FORMAT_3_4),y)
cc-ver := 0304
else ifeq ($(CONFIG_GCOV_FORMAT_4_7),y)
cc-ver := 0407
else
# Use cc-version if available, otherwise set 0
#
# scripts/Kbuild.include, which contains cc-version function, is not included
# during make clean "make -f scripts/Makefile.clean obj=kernel/gcov"
# Meaning cc-ver is empty causing if-lt test to fail with
# "/bin/sh: line 0: [: -lt: unary operator expected" error mesage.
# This has no affect on the clean phase, but the error message could be
# confusing/annoying. So this dummy workaround sets cc-ver to zero if cc-version
# is not available. We can probably move if-lt to Kbuild.include, so it's also
# not defined during clean or to include Kbuild.include in
# scripts/Makefile.clean. But the following workaround seems least invasive.
cc-ver := $(if $(call cc-version),$(call cc-version),0)
endif
obj-$(CONFIG_GCOV_KERNEL) := base.o fs.o
ifeq ($(call if-lt, $(cc-ver), 0407),1)
obj-$(CONFIG_GCOV_KERNEL) += gcc_3_4.o
else
obj-$(CONFIG_GCOV_KERNEL) += gcc_4_7.o
endif