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

[Richard Henderson]

On 9/16/22 10:08, Pierre Muller wrote:
>    I am using gcc230 machine for the gcc compile farm.
>
>    This is a big endian mips64 machine runnig Debian Buster.
>
> 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.

Yes, that host seems to have been installed with the o32 abi instead of the n64 
(or n32) abi.

>    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?

Yes.  Even gcc230 is fairly small for actually compiling qemu, it takes many hours.  So 
for many hosts we rely on cross-compilation from x86_64.

For that, we rely on the set of cross-compilers built by Debian 11 (bullseye) plus (!) the 
host libraries for that platform.  We cannot simply rely on crossbuild-essential-mips 
because building qemu requires many more system libraries than just libc.

In https://www.debian.org/releases/bullseye/, you'll note that big-endian mips is not 
listed, so we are now missing those system libraries.

We are not intending to *remove* support for big-endian mips, as 99% of the code paths are 
shared with little-endian mips, which we can continue to test.  But we are now saying that 
big-endian mips is not "supported" and might break.


r~