From: Arnd Bergmann <arnd@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Miguel Ojeda <ojeda@kernel.org>,
Fangrui Song <maskray@google.com>,
Michal Marek <michal.lkml@markovi.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 0/2] infer CROSS_COMPILE from ARCH for LLVM=1 LLVM_IAS=1
Date: Fri, 9 Jul 2021 10:07:10 +0200 [thread overview]
Message-ID: <CAK8P3a3h_tVaXVKRgaC9L+z9CwVGkOmCPPeW7UjDUhPKHNQDmw@mail.gmail.com> (raw)
In-Reply-To: <CAKwvOdkaifETNvtTA3O9EToVHAK0N50wkT-bHOpQ2RmFg7qk0A@mail.gmail.com>
On Thu, Jul 8, 2021 at 8:04 PM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@googlegroups.com> wrote:
> > /usr/bin/powerpc64-linux-gnu-gcc-5.2.0
> > /usr/bin/powerpc64-linux-gnu-gcc -> powerpc64-linux-gnu-gcc-5.2.0
> > /usr/local/bin/ppc64le-linux-gcc-9
> > ~/bin/powerpc/powerpc-linux-unknown-gcc-12.0.20210708.experimental
> >
> > all of these should be able to cross-build any powerpc kernel, but
> > there is no obvious first choice (highest version, first in path,
> > ordered list of target triples, ...). I tried coming up with a heuristic
> > to pick a reasonable toolchain, but at some point gave up because
> > I failed to express that in a readable bash or Makefile syntax.
>
> Right; foremost in my mind was arm-linux-gnueabi-gcc vs
> arm-linux-gnueabihf-gcc. That's not even to mention the versioned
> suffixes.
>
> In terms of multiversion support; this series doesn't regress doing
> things the hard/verbose way. But I think for most users we can have a
> simpler common case; folks can play with their $PATH or focus on more
> hermetic builds if they want this new feature (CROSS_COMPILE
> inference) AND support for multiple versions of the same toolchain.
Fair enough. So how something like this:
powerpc-targets := powerpc32 powerpc64 powerpc32le \
powerpc32be powerpc64le powerpc64be ppc64le ppc64be
arm-targets := arm-linux-gnueabi arm-linux-gnueabihf
x86-targets := x86_64 i386 i686
x86_64-targets := x86
i386-targets := i686 x86 x86_64
parisc-targets := hppa64 hppa
...
CROSS_COMPILE ?= `find-toolchain $(ARCH) $($(ARCH)-targets)`
where find-toolchain just finds the first working toolchain based, looking
for $(target)-linux-gcc $(target)-gcc $(target)-unknown-linux-gcc etc
in $(PATH) but ignoring the versions?
What I had actually planned was a set of helpers that allow you to
do this in multiple steps:
- if $(objtree)/scripts/cross/bin/gcc (or something else we pick)
exists and CROSS_COMPILE is not set, set CROSS_COMPILE
to $(objtree)/scripts/cross/bin/ in the Makefile
- add script to enumerate the installed toolchains
- add a second script to symlink one of those toolchains to
$(objtree)/scripts/cross/bin
- add a third script to download a cross-toolchain from kernel.org
for $(ARCH) and install it to one of the locations that the first
script looks for (/opt/cross/, $(HOME)/cross/, $(objtree)scripts/cross/)
Arnd
next prev parent reply other threads:[~2021-07-09 8:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-07 22:43 [PATCH 0/2] infer CROSS_COMPILE from ARCH for LLVM=1 LLVM_IAS=1 Nick Desaulniers
2021-07-07 22:43 ` [PATCH 1/2] Makefile: move initial clang flag handling into scripts/Makefile.clang Nick Desaulniers
2021-07-07 22:43 ` [PATCH 2/2] Makefile: drop CROSS_COMPILE for LLVM=1 LLVM_IAS=1 Nick Desaulniers
2021-07-08 8:08 ` Geert Uytterhoeven
2021-07-08 8:44 ` Masahiro Yamada
2021-07-08 10:21 ` Masahiro Yamada
2021-07-08 11:44 ` Arnd Bergmann
2021-07-08 19:06 ` Nick Desaulniers
2021-07-08 19:02 ` Nick Desaulniers
2021-07-08 19:47 ` Masahiro Yamada
2021-07-08 5:49 ` [PATCH 0/2] infer CROSS_COMPILE from ARCH " Christoph Hellwig
2021-07-08 7:27 ` Arnd Bergmann
2021-07-08 18:04 ` Nick Desaulniers
2021-07-09 8:07 ` Arnd Bergmann [this message]
2021-07-14 18:09 ` Nick Desaulniers
2021-07-14 20:18 ` Arnd Bergmann
2021-07-19 21:10 ` Nick Desaulniers
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