On 04/01/2012 21:00, Joachim Breitner wrote:
Hi,
Am Mittwoch, den 04.01.2012, 20:50 +0100 schrieb Axel Simon:
On 04.01.2012, at 17:50, Joachim Breitner wrote:
BTW, Is there a way to get the linker to create two independent copies of a library in one program space? Maybe if it is compiled as PIC (random name dropping here)? That would seem to be an elegant solution, as it makes the distro packers happy and you would not have to maintain a code copy.
In the past, I've linked a C++ library that used gmpxx against a Haskell program by renaming all symbols starting with gmp to mygmp using objcopy. Unfortunately, this is not portable and completely broke down on Mac OS when Apple moved to fat binaries (Intel and PowerPC) since their objcopy version was crippled (there doesn't even seem to be an objcopy anymore on later OS X versions). Thus, renaming symbols after compilation is non-portable and sometimes not possible without writing your own tool.
So, I propose to revert to renaming the symbols in the source code which could probably be done automatically using a lot of CPP #defines, starting from some sort of source code tar ball of gmp. This would also allow to always use the latest gmp sources without too much hassle.
Just to more random ideas that can probably easily dismissed by more knowledgeable people:
Would linking gmp statically help? E.g. is there a way to link libgmp into the RTS that the symbols are not visible to the linker any more?
Linking a static copy of GMP into the integer-gmp package is an interesting idea that I hadn't considered before. It ought to be possible, but I haven't played around with it. You would probably have to resolve all the symbols between the integer-gmp code and GMP itself when building the library, and don't expose any GMP symbols in the resulting .a file. That might mean making a big .o file containing GMP and the integer-gmp code that refers to it. I expect there would be problems with shared libraries though. You can't link the static GMP into the shared integer-gmp, because the static GMP isn't built with -fPIC.
And would dlopen make a difference? RTLD_LOCAL sounds interesting...
Maybe, I haven't looked into that. Cheers, Simon
Greetings, Joachim
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