On Tue, Mar 05, 2019 at 02:48:16PM +0900, Masahiro Yamada wrote: > Tools that are globally needed for building the kernel are supposed to > be put in the scripts/ directory, but objtool is the exceptional one. > > People were confused by objtool's Makefile since most of tools run on > the target whereas objtool runs on the host machine. Some time ago, > Douglas Anderson suggested to move tools/objtool/ to scripts/tools/ > (https://patchwork.kernel.org/patch/9983535/#20996057), but we did > not go as far as submitting a patch at that time. > > Recently, Robin Meijboom reported that the generated files for objtool > were never cleaned up. (https://patchwork.kernel.org/patch/10813797/) > > So, I looked into this to fix the distortion. Move tools/objtool/ to > scripts/objtool/, and rewrite Makefiles in the Kbuild-ish manner. > > I also cleaned up the top-level Makefile by moving the libelf check > scripts/objtool/Makefile. > > I see some benefits in this. > > [1] generated files under scripts/ are cleaned up by 'make mrproper' > > Currently, the generated files under tools/objtool/ are not cleaned up > since the build system under tools/ is a complete different world. > > If we want to clean them up, it should be done by 'make mrproper' > instead of 'make clean' since objtool is needed for building external > modules. > > This commit naturally solves the issue since Kbuild cleans under > scripts/ by 'make mrproper'. Yes, but this can be solved instead with a one-line patch. > [2] build log looks nicer > > Currently, the build log under tools/objtool/ shows absolute paths, and > displays 'DESCEND objtool' every time for incremental building. > > Switching over to the standard Kbuild scheme will improve the log. > > Before: > > DESCEND objtool > HOSTCC /home/masahiro/workspace/linux/tools/objtool/fixdep.o > HOSTLD /home/masahiro/workspace/linux/tools/objtool/fixdep-in.o > LINK /home/masahiro/workspace/linux/tools/objtool/fixdep > CC /home/masahiro/workspace/linux/tools/objtool/exec-cmd.o > CC /home/masahiro/workspace/linux/tools/objtool/help.o > CC /home/masahiro/workspace/linux/tools/objtool/pager.o > CC /home/masahiro/workspace/linux/tools/objtool/parse-options.o > CC /home/masahiro/workspace/linux/tools/objtool/run-command.o > CC /home/masahiro/workspace/linux/tools/objtool/sigchain.o > CC /home/masahiro/workspace/linux/tools/objtool/subcmd-config.o > LD /home/masahiro/workspace/linux/tools/objtool/libsubcmd-in.o > AR /home/masahiro/workspace/linux/tools/objtool/libsubcmd.a > GEN /home/masahiro/workspace/linux/tools/objtool/arch/x86/lib/inat-tables.c > CC /home/masahiro/workspace/linux/tools/objtool/arch/x86/decode.o > LD /home/masahiro/workspace/linux/tools/objtool/arch/x86/objtool-in.o > CC /home/masahiro/workspace/linux/tools/objtool/builtin-check.o > CC /home/masahiro/workspace/linux/tools/objtool/builtin-orc.o > CC /home/masahiro/workspace/linux/tools/objtool/check.o > CC /home/masahiro/workspace/linux/tools/objtool/orc_gen.o > CC /home/masahiro/workspace/linux/tools/objtool/orc_dump.o > CC /home/masahiro/workspace/linux/tools/objtool/elf.o > CC /home/masahiro/workspace/linux/tools/objtool/special.o > CC /home/masahiro/workspace/linux/tools/objtool/objtool.o > CC /home/masahiro/workspace/linux/tools/objtool/libstring.o > CC /home/masahiro/workspace/linux/tools/objtool/str_error_r.o > LD /home/masahiro/workspace/linux/tools/objtool/objtool-in.o > LINK /home/masahiro/workspace/linux/tools/objtool/objtool > > After: > > HOSTCC scripts/objtool/builtin-check.o > HOSTCC scripts/objtool/builtin-orc.o > HOSTCC scripts/objtool/check.o > HOSTCC scripts/objtool/orc_gen.o > HOSTCC scripts/objtool/orc_dump.o > HOSTCC scripts/objtool/elf.o > HOSTCC scripts/objtool/special.o > HOSTCC scripts/objtool/objtool.o > HOSTCC scripts/objtool/libstring.o > HOSTCC scripts/objtool/str_error_r.o > HOSTCC scripts/objtool/exec-cmd.o > HOSTCC scripts/objtool/pager.o > HOSTCC scripts/objtool/parse-options.o > HOSTCC scripts/objtool/run-command.o > HOSTCC scripts/objtool/sigchain.o > HOSTCC scripts/objtool/subcmd-config.o > AWK scripts/objtool/arch/x86/lib/inat-tables.c > HOSTCC scripts/objtool/arch/x86/decode.o > HOSTLD scripts/objtool/objtool That does look better. > [3] simplify distro package script > > The special handling in scripts/package/buildeb is no longer needed > since all host programs are copied to linux-headers packages. I do see the benefits. In many ways objtool is a more natural fit in the scripts dir. But there are also some downsides to this change: - This will make it harder to package objtool as a standalone tool. It has a lot of functionality that could be useful to other non-kernel projects. - It shares libsubcmd with perf. Including the subcmd .c files from tools is hacky. - It's disruptive: it will break all the out-of-tree distro kernel packaging scripts which now look for objtool in tools. You're right that objtool isn't a natural fit in tools, because it's also used as part of the build. But it's not a natural fit in scripts either. I think we've resolved most of those issues and it seems to be working well these days. So instead of disrupting everything because "make mrproper" doesn't work, I think I'd rather just do the following: diff --git a/Makefile b/Makefile index ac5ac28a24e9..7e6696c9b862 100644 --- a/Makefile +++ b/Makefile @@ -1364,7 +1364,7 @@ PHONY += $(mrproper-dirs) mrproper $(mrproper-dirs): $(Q)$(MAKE) $(clean)=$(patsubst _mrproper_%,%,$@) -mrproper: clean $(mrproper-dirs) +mrproper: clean $(mrproper-dirs) tools/objtool_clean $(call cmd,rmdirs) $(call cmd,rmfiles)
