Advice about /usr/ports/math/gmp

[Torbjorn Granlund]

We are about to release GMP 5.2.

We have been forced to add three FreeBSD-related items to the releases
notes:

  * This release will not work on FreeBSD/amd64 7.x, 8.x or 9 series
    before 9.3 with a Haswell CPU or any other CPU which supports the
    BMI2 instructions.  The reason is that the FreeBSD m4 command is not
    correctly implemented.  (Workaround: Use an older GMP release, or
    install GNU m4 from /usr/ports and tell GMP to use it.)

  * This release will not work on FreeBSD/amd64 before version 10 using
    the 32-bit ABI.  The reason is broken limits.h and broken dynamic
    linking.  (Workaround: Use an older GMP release if using the 32-bit
    ABI on these FreeBSD releases is important.)

  * This release will not work on FreeBSD/amd64 10.0 using the 32-bit
    ABI.  The reason is bugs in the compiler 'clang'.  (Workaround:
    Compiling gcc from /usr/ports might work, except that gcc depends on
    GMP; we have not been able to test that workaround since
    FreeBSD/i386 10.0 does not work for us under KVM or Xen.)

The first item is a show-stopper.  It would be possible to implement a
workaround in GMP.  We choose not to do that since (1) we adviced the
FreeBSD project two years ago the m4 bug, and FreeBSD chose to make 4
releases without fixing m4, and (2) the fix is ugly, and (3) our use of
m4 which triggers the bug is actually part of a workaround for a broken
assembler (to much complexity to maintain workarounds for workarounds).

The second item should not affect /usr/ports builds since they would use
the default 64-bit ABI on amd64 machines.

The third item is a show-stopper until clang is fixed.  We have not been
able to isolate this problem due to lack of time and due to a deeply
malfunctioning filesystem of FreeBSD/i386 under KVM and Xen+NetBSD.  We
don't have any more information about these bugs.


We do not plan to implement workarounds for the above bugs for GMP 5.2.x
for any x.  I would advice that you stick with GMP 5.1.3.


Torbjörn
Please encrypt, key id 0xC8601622