>> Can I download the bootstrap tarballs from the web interface of Hydra?

> Why not do ‘guix build bootstrap-tarballs -s x86_64-linux --target=...’?

When I tested the previous set of binaries (see the mips64el branch), it
was necessary to adjust ‘%url-base’ in ‘build-aux/download.scm’.  It
seems that now it’s not needed since they are already available on
hydra.gnu.org.

What I’ve done so far:

1. Added ‘mips64el-linux-gnuabi64’ to ‘glibc-dynamic-linker’ in
   ‘bootstrap.scm’.

2. Adjusted ‘%bootstrap-coreutils&co’ and similar procedures.

3. Created ‘mips64el-linux-gnuabi64’ in ‘gnu/packages/bootstrap/’.

4. Placed ‘bash’, ‘mkdir’, ‘tar’, ‘xz’, and ‘guile-2.0.7.tar.xz’* in
   that directory.

   * It’s 2.0.9.  I decided not to touch ‘%bootstrap-guile’ for now to
     avoid errors.

Am I on the right track?

Now, how can I test it?  My machine uses a different ABI (N32), so
‘%current-system’ is set to ‘mips64el-linux’.  I’ve already tried to run

  $ ./pre-inst-env guix build -K -s mips64el-linux-gnuabi64 hello

but that failed with

  guix build: error: build failed: a `mips64el-linux-gnuabi64' is
  required to build `/nix/store/…guile-bootstrap-2.0.drv', but I am a
  `mips64el-linux'