On Sun, Dec 05, 2021 at 02:54:05AM +0900, Masahiro Yamada wrote: > On Sun, Dec 5, 2021 at 1:53 AM Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Sat, Dec 4, 2021 at 5:13 AM Salvatore Bonaccorso <carnil@xxxxxxxxxx> wrote: > > > > > > Andreas suggested to replace the > > > > > > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH) > > > > > > with > > > > > > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(patsubst "%",%,$(CONFIG_CC_IMPLICIT_FALLTHROUGH)) > > > > Ugh. I think the external build environment is a bit broken, but > > whatever. The above is ugly but I guess it works. > > > > Another alternative would be to make the Kconfig strings simply not > > have '"' as part of them. > > > > When you do > > > > a = "hello" > > print $a > > > > in any normal language, you generally wouldn't expect it to print the > > quotes, it should just print the bare word. > > > > But that's what the Kconfig string language basically does in this > > case. And I guess several users expect and take advantage of that ;( > > > > Masahiro? Comments? > > Yes, you get to the point. > > In fact, this is in my TODO list for a while > (and this is the reason I was doing prerequisite Kconfig refactoring > in the previous development cycle). > I will try to find some spare time to complete this work. > > > > Kconfig generates two similar files, > > - .config > - include/config/auto.conf > > Changing the format of the .config is presumably problematic > since it is the saved user configuration as well. > > It is possible (and more reasonable) to change include/config/auto.conf > so strings are not quoted. > > In Makefiles, quotations are just normal characters; they have no > special functionality. > > So, in Makefile context, it is more handy to do > > CONFIG_X=foo bar > > instead of > > CONFIG_X="foo bar" > > > > One problem is include/config/auto.conf is included not only by Makefiles > but also by shell scripts. > > > In shell context, the right hand side must be quoted > in case the value contains spaces. > > CONFIG_X="foo bar" > > > > My plan is to fix > scripts/link-vmlinux.sh > scripts/gen_autoksyms.sh > etc. to not directly include the auto.conf. > Later, change Kconfig to generate the auto.conf without "". > > > > In the meantime, > > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(patsubst > "%",%,$(CONFIG_CC_IMPLICIT_FALLTHROUGH)) > > or if you prefer slightly shorter form, > > KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH:"%"=%) > > will be a workaround. It'll be nice to get this fixed. There are a few places where there is a test for a compiler flag in Kconfig, and then the option is repeated in the Makefile, due to the above quoting issues. For example: arch/arm64/Kconfig: config CC_HAS_BRANCH_PROT_PAC_RET # GCC 9 or later, clang 8 or later def_bool $(cc-option,-mbranch-protection=pac-ret+leaf) arch/arm64/Makefile: branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=pac-ret+leaf I like the $(CONFIG_CC_IMPLICIT_FALLTHROUGH:"%"=%) solution: it's short. -- Kees Cook
