Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 28 Nov 2017 20:27:43 +0100 | Subject | Re: [PATCH v3] kbuild: Set KBUILD_CFLAGS before incl. arch Makefile |
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Hi Nick,
On Tue, Nov 28, 2017 at 7:18 PM, Nick Desaulniers <ndesaulniers@google.com> wrote: > Thanks for merging Chris' patch, and sorry for taking so long to respond. > > On Wed, Nov 22, 2017 at 8:24 PM, Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: >> Linus suggests to move compiler flag testing to Kconfig. > > Do you have an LKML link for context? > > On Wed, Nov 15, 2017 at 6:32 PM, Masahiro Yamada > <yamada.masahiro@socionext.com> wrote: >> BTW, I notice another issue. >> >> If we move clang settings before including arch Makefile, >> "ifneq ($(CROSS_COMPILE),)" comes early. >> >> Some arch Makefiles (arch/mips/Makefile, arch/blackfin/Makefile, etc.) >> set CROSS_COMPILE there if CROSS_COMPILE is not given. >> >> Then, we have a conflict between two requirements among arch. >> >> [1] arm64, powerpc use ld-option in their Makefile. >> So, clang flags must be set before inc. arch Makefile. >> [2] mips, blackfin, etc. may set CROSS_COMPILE in their Makefile. >> So, we want to reference CROSS_COMPILE only after inc. arch Makefile >> >> I have no idea how to solve it. >> >> At this moment, I guess clang is intended to support >> only limited architectures. >> >> It might be OK to be compromised here. > > I definitely find it curious that certain arch's define CROSS_COMPILE > themselves. The benefit is one less argument to supply at compile > time, but it assumes that the toolchain always has a certain prefix. > This makes sense to me when cross compiling, but seems odd when > compiling natively on that arch as the host and target. Maybe those > arch's use that convention, or simply are always cross compiled for? > > Taking a survey of all arch's currently in the kernel via `cd arch; ag > CROSS_COMPILE` and quickly eyeballing the result: > > m68k if not set
And inside "ifneq ($(SUBARCH),$(ARCH))", so the prefix is not used for native compilation.
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
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
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