Re: [PATCH v2 21/30] Deprecate 32 bit big-endian MIPS

["Alex Bennée" <alex.bennee@linaro.org>]

Pierre Muller <pierre@freepascal.org> writes:

>   I am using gcc230 machine for the gcc compile farm.
>
>   This is a big endian mips64 machine runnig Debian Buster.

That's still oldstable, the current release of Debian doesn't support BE
mips in either 32 or 64 bit. As bullseye was released last year buster
will drop out of QEMU support window by August 2023 at the latest
(current LTS + 2 years or upstream drops support whichever comes first).

> When compiling the qemu 7.1.0 release source,
> the generated binaries are 32-bit mips binaries,
> and I did not find out how to generate a 64-bit versions
> of the executables.

I don't think we've ever been able to cross build QEMU BE mips64 - it was
only with buster we stopped relying on sid for access to working cross
compilers for building TCG tests:

  4575a701ea (tests/docker: move our mips64 cross compile to Buster)

>   As mips32 seems to still be the default arch that gcc uses,
> I don't really understand the idea of depreciating big endian mips32.
>
> Is this solely related to cross-compilation issues?

Decent cross-compilation support for building QEMU is the minimum we
need to ensure things don't bitrot. Ideally we would have real HW
running a non-bespoke OS with a gitlab runner so we could build *and*
run tests. However finding such HW is even harder than keeping the cross
compilation working.

>
> Pierre Muller
>
>
> More information on gcc230:
> muller@gcc230:~$ uname -a
> Linux gcc230 4.9.79-UBNT_E300 #9 SMP Tue Jul 13 13:04:47 BST 2021 mips64 GNU/Linux
> muller@gcc230:~$ cat /etc/os-release
> PRETTY_NAME="Debian GNU/Linux 10 (buster)"
> NAME="Debian GNU/Linux"
> VERSION_ID="10"
> VERSION="10 (buster)"
> VERSION_CODENAME=buster
> ID=debian
> HOME_URL="https://www.debian.org/"
> SUPPORT_URL="https://www.debian.org/support"
> BUG_REPORT_URL="https://bugs.debian.org/"
> muller@gcc230:~$ gcc --version
> gcc (Debian 8.3.0-6) 8.3.0
> Copyright (C) 2018 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> muller@gcc230:~$ gcc -print-libgcc-file-name
> /usr/lib/gcc/mips-linux-gnu/8/libgcc.a
> muller@gcc230:~$ gcc -mabi=64 -print-libgcc-file-name
> /usr/lib/gcc/mips-linux-gnu/8/64/libgcc.a


-- 
Alex Bennée