It has been changed to behave more like an autoconf-generated
configure script. Please see --help for more information.
Some options have been removed including --cflags and --compiler.
Other options have been renamed and have different semantics
now (headers and library specify full path).
Previously, we wouldn't build on 32-bit architectures, let alone
configure. This was due in part to some issues where we essentially
ignored setting CFLAGS properly.
In addition, FreeBSD and possibly other BSDs only report i386 for any
32-bit x86 architecture. This has the side-effect that we have to do
some additional guesswork to determine the actual CPU. Since we make use
of cmpxchg8b, we require an i586 machine. FreeBSD's default 32-bit gcc
-march setting is i486, so in effort to make things easier for FreeBSD
users on 32-bit, set that to i586 by default.
Linux makes this a little easier for us, since its uname actually
returns useful information about the architecture (and assumedly the
compilers for that architecture target the same arch at a minimum), so
we will refuse to work on i386 / i486 on Linux as well.
But really, I'd be slightly surprised at a ton of use on pentium/k5.