On Fri, Apr 13, 2012 at 04:36:07PM -0400, Adam Jackson wrote: > On 4/13/12 3:19 PM, Richard W.M. Jones wrote: > >On Fri, Apr 13, 2012 at 10:47:00AM -0700, Toshio Kuratomi wrote: > >>Although (since I know Rich works on OCaml stuff) since OCaml is compiled to > >>C before being compiled to object code, this section might still apply. > > > >OCaml isn't compiled to C, it's compiled direct to machine code. > > > >The OCaml native code compiler supports -fPIC output. I'm not quite > >sure if PIE is just PIC applied to the main program, or if there is > >some other magic it does. > > PIE produces a position independent executable. This is not the > same thing as an executable that just happens to have been linked > together from PIC code. It's more like a DSO that happens to have a > main() function. As usual I'm being dumb, but I still don't understand the difference. Anyhow we're not quite there with OCaml: $ echo 'print_endline "hello"' > foo.ml $ ocamlopt -fPIC foo.ml $ readelf -d a.out | grep TEXTREL # [1] $ ocamlopt -fPIC -cclib -pie foo.ml /usr/bin/ld: /usr/lib64/ocaml/libasmrun.a(roots.o): relocation R_X86_64_32S against `caml_frametable' can not be used when making a shared object; recompile with -fPIC /usr/lib64/ocaml/libasmrun.a: could not read symbols: Bad value collect2: error: ld returned 1 exit status File "caml_startup", line 1, characters 0-1: Error: Error during linking That static library includes the garbage collector. I have a non-upstream patch which makes the runtime into a shared library, and it's probably a good time to look at that again. Is there anything else apart from passing -fPIC to the compiler and -pie to the linker which needs to be done to make a PIE executable? Rich. [1] http://www.linuxfromscratch.org/~manuel/hlfs-book/glibc-2.4/chapter02/pie.html -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://et.redhat.com/~rjones/virt-df/ -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
