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Jeff Squyres 814f3e9caa hwloc: clarify --with-hwloc behavior
Clarify in README what --with-hwloc does in its different use cases.

Also, ensure that the behavior when specifying `--with-hwloc` is the
same as if that option is not specified at all.  This is what we did
in Open MPI <= v3.x; looks like we inadvertantly caused `--with-hwloc`
to be synonymous with `--with-hwloc=external` in v4.0.0.

Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
(cherry picked from commit 18c3e1af5ef281e8b502a7ad778256889cc707d1)
2019-12-19 12:30:40 -08:00
..
2015-06-23 20:59:57 -07:00

12 Sep 2011

Notes for hwloc component maintainers:

1. There can only be *1* hwloc version component at a time.
   Specifically: if there are multiple hwlocXYZ components (i.e.,
   different versions of hwloc), then they must all be .ompi_ignore'd
   except for 1.  This is because we currently m4_include all of the
   underlying hwloc's .m4 files -- if there are multiple hwlocXYZ
   components, I don't know if m4 will barf at the multiple,
   conflicting AC_DEFUNs, or whether it'll just do something
   completely undefined.

1a. As a consequence, if you're adding a new hwloc version component,
   you'll need to .ompi_ignore all others while you're testing the new
   one.

2. If someone wants to fix #1 someday, we might be able to do what we
   do for libevent: OPAL_CONFIG_SUBDIR (instead of slurping in hwloc's
   .m4 files).