Re: libffi illegal instruction - again

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Ken!

On Nov 3, 2021, at 6:43 PM, Ken Cunningham <ken.cunningham.webuse@gmail.com> wrote:

It appears that when building portable code, the ax_gcc_archflag.m4 macro clears -mcpu for almost every arch except powerpc:

https://github.com/libffi/libffi/blob/master/m4/ax_gcc_archflag.m4#L241

 case $host_cpu in i*86|x86_64*|amd64*) flag_prefixes="$flag_prefixes -mcpu= -m";; esac



The fact that PowerPC is excluded must result in m4 passing the “-mcpu=“ flag matching the buildbot’s CPU, and breaks everything older than the buildbot.

The problem is not exclusive to PowerPC but also SPARC and 32-bit x86. It used to work before with version 3.4.2 in experimental:

See: https://buildd.debian.org/status/fetch.php?pkg=libffi&arch=powerpc&ver=3.4.2-1&stamp=1626443428&raw=0

I‘m pretty confident that my analysis is correct and the problem is triggered by the new autoconf version.

Adrian