v2.0.x: Open BSD 6.0 and patcher problems

[hppritcha]

As reported by Paul H., Open BSD 6.0 disallows the patcher code's mprotect call.

See https://mail-archive.com/[email protected]/msg19527.html

This impacts master and v2.x

[PHHargrove]

FYI:

I have confirmed w/ the released 2.0.1 tarball that configuring with --enable-mca-no-build=patcher is sufficient to avoid the problem, such that I can pass make check and run ring_c, on both i386 and amd64 systems running OpenBSD-6.0

I suggest that a possible solution is to have the configure probe for the patcher framework attempt an mprotect() call with prot = PROT_EXEC|PROT_READ|PROT_WRITE. Then the problematic code would be automatically disqualified not only on OpenBSD-6, but also on any future OSes (including Linux and Mac OS X) with strong "W^X" policies.

-Paul

[jsquyres]

Per the call today, @artpol84 is going to check to see if Mellanox cares about Open BSD.

[hppritcha]

Mellanox does not care about Open BSD - per discussion devel telecon

[jsquyres]

@hjelmn Will add some kind of disabling for the patcher on Open BSF 6.0 systems.

[jsquyres]

@hjelmn says he can work on this next week.

[hppritcha]

we'd like this fixed in 2.0.2 but not a blocker.

[PHHargrove]

Current (2.0.2rc3) it is not possible to run on OpenBSD-6 unless one configures with --enable-mca-no-build=patcher.
Would it be appropriate to document this in README for v2.0.2?

[hppritcha]

done, PR #2687