Hi Yamada-san,
On Wed, Jul 21, 2021 at 6:05 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
> On Wed, Jul 21, 2021 at 4:58 AM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
> > On Tue, Jul 20, 2021 at 7:43 PM Linus Torvalds
> > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > On Tue, Jul 20, 2021 at 1:05 AM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
> > >
> > > We do most of the other heavy lifting in this area in Kconfig anyway,
> > > why not add that compiler choice?
> > >
> > > Obviously it would be gated by the tests to see which compilers are
> > > _installed_ (and that they are valid versions), so that it doesn't ask
> > > stupid things ("do you want gcc or clang" when only one of them is
> > > installed and/or viable).
> >
> > I don't see a good way of making Kconfig options both select the
> > compiler and defining variables based on the compiler, since that
> > would mean teaching Kconfig about re-evaluating all compiler
> > dependent settings whenever the first option changes.
> >
> > I do have another idea that I think would work though.
> >
> > > Hmm? So then any "LLVM=1" thing would be about the "make config"
> > > stage, not the actual build stage.
> > >
> > > (It has annoyed me for years that if you want to cross-compile, you
> > > first have to do "make ARCH=xyz config" and then remember to do "make
> > > ARCH=xyz" for the build too, but I cross-compile so seldom that I've
> > > never really cared).
> >
> > The best thing that I have come up with is a pre-configure step, where
> > an object tree gets seeded with a makefile fragment that gets included
> > for any 'make' invocation. This would set 'ARCH=', 'CROSS_COMPILE',
> > 'CC=' and possibly any other option that gets passed to 'make' as
> > a variable and has to exist before calling 'make *config'.
>
>
> There is no need to add a hook to include such makefile fragment(s).
>
> Quite opposite, you can put your Makefile (in a different filename)
> that includes the top Makefile.
>
>
> I think this is what people are already doing:
>
>
> GNU Make looks for 'GNUmakefile', 'makefile', and 'Makefile'
> in this order.
Exactly. I only have a few source repositories, but lots of build directories
(I never build in a repo directory). Each build directory has a GNUmakefile:
build/linux-riscv-starlight$ cat GNUmakefile
MAKEARGS = ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-
include ~/linux/default.mk
build/linux-riscv-starlight$ cat ~/linux/default.mk
MAKEFLAGS += --no-print-directory
.PHONY: all $(MAKECMDGOALS)
all := $(filter-out all Makefile,$(MAKECMDGOALS))
all:
@$(MAKE) $(MAKEARGS) $(all) -f Makefile
Makefile:;
$(all): all
@:
%/: all
@:
build/linux-riscv-starlight$
Perhaps we could have a "make setup ARCH=foo CROSS_COMPILE=bar" target,
which creates such a GNUmakefile?
P.S. I put the extra logic in ~/linux/default.mk, so I don't have to update all
GNUmakefiles when I want to make a change to the main logic.
For build dirs where I want to track a specific config, I have a slightly
different version:
build/linux-m68k-allmodconfig-sun3$ cat GNUmakefile
MAKEARGS = ARCH=m68k KCONFIG_ALLCONFIG=1
DEFCONFIG = allmodconfig
include ~/linux/override-oldconfig.mk
build/linux-m68k-allmodconfig-sun3$ cat ~/linux/override-oldconfig.mk
MAKEFLAGS += --no-print-directory
.PHONY: all oldconfig realoldconfig $(MAKECMDGOALS)
all := $(filter-out all oldconfig realoldconfig
Makefile,$(MAKECMDGOALS))
all:
@$(MAKE) $(MAKEARGS) $(all) -f Makefile
# Replace oldconfig by $(DEFCONFIG)
oldconfig:
@$(MAKE) $(MAKEARGS) $(DEFCONFIG) -f Makefile
realoldconfig:
@$(MAKE) $(MAKEARGS) oldconfig -f Makefile
Makefile:;
$(all): all
@:
%/: all
@:
build/linux-m68k-allmodconfig-sun3$
That way I can always just type "make oldconfig", and it will do what
I want.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
