Re: [Haskell-cafe] Partial statical linking

24 Sep 2012

      2012/9/19 Brandon Allbery :
...
On Wed, Sep 19, 2012 at 7:06 AM, Jason Dusek  wrote:
...
What I attempted was building a binary with only some C libraries
statically linked, with this command line:
# Build https://github.com/erudify/sssp on Ubunut 12.04
  ghc -outputdir ./tmp -v --make -O2 sssp.hs -o sssp.ubuntu \
    /usr/lib/x86_64-linux-gnu/libffi.a \
    /usr/lib/x86_64-linux-gnu/libgmp.a \
    /usr/lib/x86_64-linux-gnu/libz.a
However, this really made no difference. Running `ldd' on the
resulting binary reveals that libz and friends are still
dynamically linked:
On Linux you probably need -optl--whole-archive for this to do anything;
alternately, you would need to get the final ld command line out of ghc and
insert the above libraries into it *after* the package .a files.
Putting them before the packages (including the GHC runtime) that need them,
as will happen by default, will cause them to be ignored because they
contain no required symbols *at that point* in the link.  --whole-archive
tells to blindly link the whole static archive in instead of ignoring it.
Hi Brandon,

This turned out to be the right ticket. The full command line is
like this:

  ghc -outputdir ./tmp --make -O2 sssp.hs -o sssp.ubuntu \
    -optl-Wl,--whole-archive \
      /usr/lib/x86_64-linux-gnu/libffi.a \
      /usr/lib/x86_64-linux-gnu/libgmp.a \
      /usr/lib/x86_64-linux-gnu/libz.a \
    -optl-Wl,--no-whole-archive

Without the --no-whole-archive at the end, I get errors like:

  (.text+0x880): multiple definition of `__morestack_unblock_signals'
  /usr/lib/gcc/x86_64-linux-gnu/4.6/libgcc.a(generic-morestack.o):(.text+0x880):
first defined here
  /usr/lib/gcc/x86_64-linux-gnu/4.6/libgcc.a(generic-morestack.o): In
function `__morestack_allocate_stack_space':

I am not sure why that happens -- libgcc.a wasn't explicitly
asked for; but it stands to reason that one shouldn't specify
--whole-archive for everything GHC links, just the archives of
interest. Life is short and art is long.

--
Jason Dusek
pgp // solidsnack // C1EBC57DC55144F35460C8DF1FD4C6C1FED18A2B