Re: [PATCH v2 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for LLVM=1 LLVM_IAS=1

From: Masahiro Yamada <masahiroy@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Miguel Ojeda <ojeda@kernel.org>,
	Fangrui Song <maskray@google.com>,
	Michal Marek <michal.lkml@markovi.net>,
	Arnd Bergmann <arnd@kernel.org>,
	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>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Christoph Hellwig <hch@infradead.org>,
	Nathan Chancellor <nathan@kernel.org>
Subject: Re: [PATCH v2 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for LLVM=1 LLVM_IAS=1
Date: Wed, 21 Jul 2021 14:12:23 +0900	[thread overview]
Message-ID: <CAK7LNAROLTHfz7d93xNx-MWj1-dsxD+7=OFGd8z078kdSRigPA@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=whS1zBU=uhDTk2M1LwkqG7AKLsR0_+XG+saY_s2FHZr-A@mail.gmail.com>

On Wed, Jul 21, 2021 at 8:20 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Tue, Jul 20, 2021 at 2:54 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > But there are other things that stick around. In particular, I have
> > considered simply using git config variables for that.
> >
> > Something like this in the main Makefile:
>
> A slightly more fleshed-out patch to do this just to see if somebody
> wants to work on something like this.
>
> It really would seem to make it very easy to set up any random build
> environment, and not have to remember it once it's done.
>
> There are probably better ways to do this, I normally try to avoid
> doing Makefile magic, since others have taken it over. Masahiro?

The patch would uglify the Makefile.

If git is not installed, $(shell git config  ...)
will spit an error message, so '2>/dev/null' is needed.

Actually, I believe we should be able to build the kernel
from a source tarball without relying on git in any way.

In fact, we rely on git in some places, for example,
scripts/setlocalversion can add commit hash to the release
string, but I want to minimize the git-dependent code.

>              Linus
>
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-- 
Best Regards
Masahiro Yamada