Commit-ID: d7b4d6de57d414a6384376880f2caf7125a45494 Gitweb: http://git.kernel.org/tip/d7b4d6de57d414a6384376880f2caf7125a45494 Author: Steven Rostedt <srostedt@xxxxxxxxxx> AuthorDate: Mon, 18 Oct 2010 14:42:00 -0400 Committer: Steven Rostedt <rostedt@xxxxxxxxxxx> CommitDate: Mon, 18 Oct 2010 17:08:10 -0400 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@xxxxxxxxxxxx> ] Reported-by: Ingo Molnar <mingo@xxxxxxx> Tested-by: Ingo Molnar <mingo@xxxxxxx> Cc: Michal Marek <mmarek@xxxxxxx> Cc: linux-kbuild@xxxxxxxxxxxxxxx Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx> --- scripts/Makefile.build | 8 +++++++- 1 files changed, 7 insertions(+), 1 deletions(-) diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 4db60b2..843bd4f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -210,7 +210,13 @@ endif ifdef CONFIG_FTRACE_MCOUNT_RECORD ifdef BUILD_C_RECORDMCOUNT -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; else cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \ "$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \ -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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