>> I’ve already tried that:
>>
>> $ ./pre-inst-env guix build -K -s mips64el-linux-gnuabi64 hello
>>
>> […]
>>
>> ERROR: bootstrap binary not found "tar" "mips64el-linux-gnuabi64"

> As I wrote, call it ‘mips64el-linux’, and put the binaries under the
> directory of that name.

I did that but forgot to adjust ‘-s mips64el-linux-gnuabi64’.  So I’ve
just tried this command:

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

The bootstrap Guile binary that I fetched from Hydra [1] aborts when
‘./guile --version’ is called.  But this one works [2].  What has
happened?

I’ve also tested ‘./tar --version’ (the one from Hydra), and it works.

Could you run the following command and paste the hashsums?

$ ./pre-inst-env guix build bootstrap-tarballs -s x86_64-linux --target=mips64el-linux-gnuabi64

[1] https://lists.gnu.org/archive/html/guix-devel/2013-09/msg00046.html
[2] http://www.fdn.fr/~lcourtes/tmp/guile-static-stripped-2.0.9-mips64el-linux-gnuabi64.tar.xz