>> I think adding something like
>>     (arguments
>>      '(#:configure-flags
>>        (list "CFLAGS=-march=mips64 -mabi=64")))
>> to %bootstrap-glibc or maybe %glibc-for-bootstrap (whatever is used to 
>> obtain the bootstrap glibc) should do the trick.

> It’s %glibc-for-bootstrap in make-bootstrap.scm.

> You would actually add those CFLAGS to the configure flags already in there.

OK, I added the above.  I'm going to build the bootstrap tarballs (as
suggested in 'HACKING').