At Tue, 28 May 2013 14:28:04 +0100, David Griffiths wrote: > Hi Matthew, > > On 24/05/13 23:54, David Griffiths wrote: > > On 24/05/13 18:44, Matthew Flatt wrote: > >> At Thu, 23 May 2013 14:43:18 +0100, David Griffiths wrote: > >>> I've been getting a problem for some time building against the racket > >>> ubuntu packages on 64 bit: > >>> > >>> /usr/bin/ld: /usr/lib/libracket3m.a(salloc.o): relocation > >>> R_X86_64_TPOFF32 against `scheme_thread_locals' can not be used when > >>> making a shared object; recompile with -fPIC > >>> > >>> Any chance this can be resolved? > >> > >> Is this with a vanilla Racket build (e.g., no `--enable-shared')? > > > > Probably - this is using the packages in the main PLT ubuntu launchpad > > ppa. I imagine they are built with vanilla settings. > > > >> And it's happening when you link your program to "libracket3m.a", as > >> opposed to just building Racket, right? > > > > Right. > > > >> Is your code compiled `-fPIC' (while the Racket code isn't, I think)? > > > > It is indeed, as I'm building shared objects to load as racket modules. > > > > I'm not clear why this is a problem with 64bit and not with 32, but I am > > a little rusty on this stuff... > > Any ideas on where the solution to this would be? > Are the Ubuntu package maintainers on this list?
A drawback of adding `-fPIC' to the Racket build by default is that everyone would pay a little of performance. For example, racket -c -l racket seems to take 5-8% longer when Racket is compiled with -fPIC. That's probably about the worst-case hit, though, since loading `racket' from source spends a lot of time in the C-implemented run-time system. An example that spends all its time in JIT-generated code is unaffected. (I also tried GC-intensive examples, but `-fPIC' doesn't seem to have much effect on the Racket GC.) Since the cost isn't so big, so I think it might be ok to add -fPIC to the Ubuntu PPA's build. Another option is adding it as a default flag for 64-bit Linux at the `configure' level, but that seems more complex. But how important is it in your context to use the PPA-supplied "libracket3m.a"? You could build your own "libracket3m.a" from the Racket source, suppling `CPPFLAGS=-fPIC' to `configure'. (On 32-bit x86 Linux, -fPIC isn't required for shared libraries.) ____________________ Racket Users list: http://lists.racket-lang.org/users
