Document supported platforms

[Dan Bonachea]

Somewhere in the release documentation we need to document what platforms are supported by the implementation.

This should include at least:

• C++ Compiler families (with minimum versions)
• Operating Systems (with any known minimum versions)
• Processor architectures or ABI restrictions (eg the current implementation is 64-bit only)
• GASNet conduits/networks

The informal list we've been tossing around so far for the September release is:

• Linux + gcc (what versions?) + x86_64 + smp/udp/ibv(?)
• Mac OSX (what versions?) + clang (what version?) + x86_64 + smp/udp
• Cray XC + PrgEnv-gnu (gcc 6.3.0) + x86_64 + aries

This list needs to be fleshed out with more detailed info and any restrictions.

[Paul Hargrove]

I've opened two new issues which I would link as blocking this one if such a capability were available.
I chose to open these as independent issues because they may each involve a non-trivial amount of discussion:

• Issue #29: Document minimum clang/Xcode version on Mac OSX
• Issue #31: Document minimum clang version on Linux

Based on comments in other issues, I suspect Cray XC + PrgEnv-gnu may work significantly earlier than 6.3.0 (probably 5.2.0). I will comment here again if/when I learn more (perhaps with a link to another new issue if the result isn't clear-cut).

[Paul Hargrove]

I have confirmed that "Cray XC + PrgEnv-gnu (gcc 5.2.0) + x86_64" works (and gcc/4.9.3 does not).
By works I mean everything in tests/ can be compiled and run on Edison.

Additionally I've verified that gcc/5.2.0 is sufficient to build and run tests/* with smp-conduit on the front-end.

[Paul Hargrove]

Looking more at gcc on Linux I see gcc-5.1.0 works as well (as Amir predicted in issue #19).

[Paul Hargrove]

Here is a summary of what I have been able to determine with respect to compilers with the current develop as of Sept 6:

• Mac OS X 10.11, 10.12 and 10.13beta (El Capitan, Sierra and High Sierra, respectively) with the most recent Xcode releases for each, though it is suspected that any Xcode release 8.0 or newer will work. [smp and udp conduits]
• Linux/x86-64 with gcc-5.1.0 or newer, or with clang-3.7.0 when using libstdc++ from gcc-5.1.0 (but see the note [to be provided] about use of non-system compilers. [smp, udp and ibv conduits]
• Cray XC with PrgEnv-gnu and gcc/5.2.0 (or later) environment modules loaded [smp and aries conduits]

[Dan Bonachea]

fix issue 18: document currently supported platforms

Document the list of platforms currently known to work.

Minor cosmetic tweaks to README.md.

→ <<cset 28fd426cd5ab>>

[Dan Bonachea]

Merge pull request #1 into develop

• issue18: Add install-time checking of platform support fix issue 18: document currently supported platforms Convert EOLs in README.md

→ <<cset 5ecd40875e2b>>