linux-kernel - Re: Updating kernel.org cross compilers?

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Date:   Sun, 30 Apr 2017 00:29:57 -0500
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Andre Przywara <andre.przywara@....com>
Cc:     Tony Breeds <tony@...eyournoodle.com>,
        Guenter Roeck <linux@...ck-us.net>,
        LKML <linux-kernel@...r.kernel.org>,
        LAKML <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: Updating kernel.org cross compilers?

Hi,

On Wed, Apr 26, 2017 at 03:14:16PM +0100, Andre Przywara wrote:
> It seems that many people (even outside the Linux kernel community) use
> the cross compilers provided at kernel.org/pub/tools/crosstool.
> The latest compiler I find there is 4.9.0, which celebrated its third
> birthday at the weekend, also has been superseded by 4.9.4 meanwhile.
> 
> So I took Segher's buildall scripts from [1] and threw binutils 2.28 and
> GCC 6.3.0 at them.

Happy to see people are still using these!

> After removing --enable-sjlj-exceptions from build-gcc

This was needed to build some targets.  It does prevent aarch64 from
building without patch.

> and adding --disable-multilib (for building x86-64 on a x86-64
> box without 32-bit libs)

Why is this needed?  What error are you seeing.

> I was able to build (bare-metal) toolchains for
> all architectures except arc, m68k, tilegx and tilepro.

arc needs a more recent GCC; the other probably as well.  GCC 7 should
be out very soon, you probably want to wait for that :-)

> $ ./buildall --toolchain
> $ PATH=$PATH:/opt/cross/bin
> $ ./buildall --kernel

You should have the target dir in your PATH before doing anything else.
Is this not documented?  Hrm I guess not, let me fix that.

> And what is a good build setup, so that the binaries run on as many
> systems as possible?

Run contrib/download_prerequisites in the gcc source dir: this will
make GMP, MPFR, MPC statically linked, and use a version of each that
is known to work (and work correctly).

> [1] http://git.infradead.org/users/segher/buildall.git/

I'll push some changes that make aarch64 work out-of-the-box in a
minute.  It does some other things as well (e.g., make ia64 work again
after *that* change); more changes are still needed to make sh4 work
without patches.

Segher