[GHC] #7942: aarch64 support in ghc

[GHC]

#7942: aarch64 support in ghc
--------------------------------------------+------------------------------
        Reporter:  jcapik                   |            Owner:
            Type:  feature request          |           Status:  new
        Priority:  normal                   |        Milestone:  7.10.1
       Component:  Compiler                 |          Version:  7.6.3
      Resolution:                           |         Keywords:
Operating System:  Linux                    |     Architecture:  arm
 Type of failure:  GHC doesn't work at all  |       Difficulty:  Unknown
       Test Case:                           |       Blocked By:  7623, 8664
        Blocking:                           |  Related Tickets:
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Comment (by cjwatson):

 I've been working with Karel Gardas (kgardas) to get this going, and I've
 now completed an unregisterised GHC bootstrap on Ubuntu arm64.  I started
 by cross-building GHC 7.8 using variations on Karel's patch set, and then
 bodged together a GHC 7.6 build (since that's what we're shipping on other
 architectures) bootstrapping off that.  This all now appears to be working
 fine and I should be able to get binaries into our archive in the next few
 days.

 I'm attaching a patch (made against the ghc-7.8 branch); most of it is
 Karel's from https://ghcarm.wordpress.com/2014/01/18/unregisterised-ghc-
 head-build-for-arm64-platform/, I've just tweaked it a bit given that I
 had the advantage of access to real hardware.  Some of this may be
 unnecessary for an unregisterised build, but it doesn't hurt.  It would be
 great if somebody could review and apply it, since it's a lot easier to
 get started on more advanced things like LLVM or NCG support if you don't
 have to do the time-consuming bootstrap yourself.  Please note that you
 also need to update the embedded copy of libffi in `libffi-tarballs/` to
 at least version 3.0.12.

 Karel's initial patch caused `GHC_CONVERT_CPU` to return `arm64`.  I
 changed this to `aarch64`, since the return value of `GHC_CONVERT_CPU` is
 used to construct the `--host` option for configure scripts and thus it
 needs to be valid as the first part of a GNU config triplet.  I left the
 Haskell-level architecture name as `ArchARM64`, since that style is more
 common as a user-facing name for the architecture: for example, the Linux
 kernel returns `arm64` in its `uname` output.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7942#comment:24>
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