path: root/scripts/Makefile.build
diff options
authorSteven Rostedt <srostedt@redhat.com>2010-10-18 14:42:00 -0400
committerSteven Rostedt <rostedt@goodmis.org>2010-10-18 17:08:10 -0400
commitd7b4d6de57d414a6384376880f2caf7125a45494 (patch)
tree5c8e6fbe25157136cab42ca0fa6f03b065cbbb69 /scripts/Makefile.build
parentf92f6e6ee35d2779aa62e70f78ad8e1cd417eb52 (diff)
ftrace: Remove recursion between recordmcount and scripts/mod/empty
When DYNAMIC_FTRACE is enabled and we use the C version of recordmcount, all objects are run through the recordmcount program to create a separate section that stores all the callers of mcount. The build process has a special file: scripts/mod/empty.o. This is built from empty.c which is literally an empty file (except for a single comment). This file is used to find information about the target elf format, like endianness and word size. The problem comes up when we need to build recordmcount. The build process requires that empty.o is built first. The build rules for empty.o will try to execute recordmcount on the empty.o file. We get an error that recordmcount does not exist. To avoid this recursion, the build file will skip running recordmcount if the file that it is building is script/mod/empty.o. [ extra comment Suggested-by: Sam Ravnborg <sam@ravnborg.org> ] Reported-by: Ingo Molnar <mingo@elte.hu> Tested-by: Ingo Molnar <mingo@elte.hu> Cc: Michal Marek <mmarek@suse.cz> Cc: linux-kbuild@vger.kernel.org Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'scripts/Makefile.build')
1 files changed, 7 insertions, 1 deletions
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 4db60b2e2a7..843bd4f4ffc 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -210,7 +210,13 @@ endif
-cmd_record_mcount = $(objtree)/scripts/recordmcount "$(@)";
+# Due to recursion, we must skip empty.o.
+# The empty.o file is created in the make process in order to determine
+# the target endianness and word size. It is made before all other C
+# files, including recordmcount.
+cmd_record_mcount = if [ $(@) != "scripts/mod/empty.o" ]; then \
+ $(objtree)/scripts/recordmcount "$(@)"; \
+ fi;
cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \