GHC on ARM

During my “Linux Kernel Modules with Haskell” tech talk I mentioned my next personal project (on my already over-full plate) would be to play with Haskell on ARM.  I’m finally getting around to a little bit of playing!  Step zero was to get hardware so I acquired a touchbook – feel free to ignore all the marketing on that site (though I am quite happy with it) and just understand it is the equivalent of a beagleboard with keyboard, touch-pad, touch screen, speakers, wifi, bluetooth, two batteries, more USB ports, and a custom Linux distribution.

Step 1: Get an Unregistered Build

To start its best to bypass the porting GHC instructions and steal someone elses porting effort in the form of a Debian package (actually, three debian packages).  Convert them to a .tar.gz (unless you have a debian OS on your ARM system) using a handy deb2targz script.  Now untar them onto your ARM system via “sudo tar xzf oneOfThePackages.tar.gz -C /” .  Be sure to copy the package.conf  as it seems to be missing from the .debs “sudo cp /usr/lib/ghc-6.10.4/package.conf.shipped /var/lib/ghc-6.10.4/package.conf”.   After all this you should have a working copy of GHC 6.10.4 – confirm that assertion by compiling some simple test programs.

I now have my copy of 6.10.4 building GHC 6.12.1.  The only hitch thus far was needing to add -mlong-calls to the C options when running ./configure.  With luck I will soon have an unregistered GHC 6.12.1 on my ARM netbook.  I’ll edit this post tomorrow with results (yes, I’m actually compiling on the ARM and not in an x86 + QEMU environment).

Step 2: Get a registered build – upstream patches

This is where things become more black-box to me.  I want to make a native code generator (NCG) for GHC/ARM.  There are some decent notes about the RTS at the end of the previously mentioned porting guide and there is also a (up-to-date?) page on the NCG.  Hopefully this, combined with the GHC source, will be enough but I’ll probably be poking my head into #ghc more often.

Step 3: Write more Haskell

The purpose of all of this was to use Haskell on my ARM system.  Hopefully I’ll find time to tackle some problems that non-developers will care about!