libpthread fails to build as an add-on

[ludo@gnu.org (Ludovic Courtès)]

(Hurd people: this is about a configure error when cross-compiling glibc
with libpthread as an add-on.)

Manolis Ragkousis <manolis837@gmail.com> skribis:

> when building glibc with libpthread as an addon I get this
>
> configure: running configure fragment for add-on libpthread
> configure: WARNING: you should use --build, --host, --target
> configure: WARNING: you should use --build, --host, --target
> checking build system type... Invalid configuration `dummy': machine
> `dummy' not recognized
> configure: error:
> /gnu/store/281n6ma5jxy9sb3nwc09mzpqx43vczr6-bash-4.2/bin/bash
> ../source/scripts/config.sub dummy failed
>
> Normally the flags passed to glibc's configure should be passed to
> libpthread as well. Why isn't it happening?

Actually libc’s configure doesn’t use the normal AC_CONFIG_SUBDIRS
mechanism, and instead runs add-on configure scripts by itself, without
arguments AFAICS.

[...]

> It was created by GNU C Library configure (see version.h), which was
> generated by GNU Autoconf 2.68.  Invocation command line was
>
>   $ ../source/configure dummy readelf

(This is libpthread’s config.log, right?)

I don’t understand where those arguments come from.

Ideas?

Thanks,
Ludo’.