Dynamic Libraries
I have encountered something that I do not understand. Everything works fine. Basically I have a bunch of user modules (low level) that are built into a dynamic library. If I write top level code that calls modules in that library, everything works just fine on i386 and AMD64. However, the application involved has another library of modules. Some of them call modules in the low level library. The top level code call modules in both libraries. Often when it calls a module in the mid level library, that module calls several modules in the low level library. All this works just fine on i386. However, when I compile everything on AMD64 I get an error message that says the lower level library needs to be compiled with fPIC. If I add that to the Makefile for the lower level library and rebuild everything, it all works again. I don't understand why the fPIC is required for AMD64. Also, how do I tell if the lower level library is being dynamically linked at run time, or being directly incorporated into the mid level library or top level application? Since both of these libraries are quite large, and they are in use by a number of top level applications, I want just one copy to exist in physical memory.___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: Dynamic Libraries
Doug Hardie wrote: I have encountered something that I do not understand. Everything works fine. Basically I have a bunch of user modules (low level) that are built into a dynamic library. If I write top level code that calls modules in that library, everything works just fine on i386 and AMD64. However, the application involved has another library of modules. Some of them call modules in the low level library. The top level code call modules in both libraries. Often when it calls a module in the mid level library, that module calls several modules in the low level library. All this works just fine on i386. However, when I compile everything on AMD64 I get an error message that says the lower level library needs to be compiled with fPIC. If I add that to the Makefile for the lower level library and rebuild everything, it all works again. I don't understand why the fPIC is required for AMD64. Also, how do I tell if the lower level library is being dynamically linked at run time, or being directly incorporated into the mid level library or top level application? Since both of these libraries are quite large, and they are in use by a number of top level applications, I want just one copy to exist in physical memory. This sounds exactly like compiling with clang through ccache. There are issues with clang and ccache cooperation. Actually the one you may hit is libtool detecting implicit fPIC requirement when running clang through ccache. -- Sphinx of black quartz judge my vow. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: Dynamic Libraries
On 7 March 2012, at 01:40, Volodymyr Kostyrko wrote: Doug Hardie wrote: I have encountered something that I do not understand. Everything works fine. Basically I have a bunch of user modules (low level) that are built into a dynamic library. If I write top level code that calls modules in that library, everything works just fine on i386 and AMD64. However, the application involved has another library of modules. Some of them call modules in the low level library. The top level code call modules in both libraries. Often when it calls a module in the mid level library, that module calls several modules in the low level library. All this works just fine on i386. However, when I compile everything on AMD64 I get an error message that says the lower level library needs to be compiled with fPIC. If I add that to the Makefile for the lower level library and rebuild everything, it all works again. I don't understand why the fPIC is required for AMD64. Also, how do I tell if the lower level library is being dynamically linked at run time, or being directly incorporated into the mid level library or top level application? Since both of these libraries are quite large, and they are in use by a number of top level applications, I want just one copy to exist in physical memory. This sounds exactly like compiling with clang through ccache. There are issues with clang and ccache cooperation. Actually the one you may hit is libtool detecting implicit fPIC requirement when running clang through ccache. The Makefile specifies GCC and its FreeBSD 8.0. I don't believe clang was in that soon, but I may be wrong. How can I check that? Where is clang? I have installed 9.0 on another system but haven't had time to try that out yet. ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: Dynamic Libraries
On Wed, Mar 07, 2012 at 12:53:13AM -0800, Doug Hardie wrote: All this works just fine on i386. However, when I compile everything on AMD64 I get an error message that says the lower level library needs to be compiled with fPIC. If I add that to the Makefile for the lower level library and rebuild everything, it all works again. I don't understand why the fPIC is required for AMD64. It is a requirement of the architecture. It is explained e.g. in: http://www.technovelty.org/code/c/amd64-pic.html Also, how do I tell if the lower level library is being dynamically linked at run time, or being directly incorporated into the mid level library or top level application? Examine the application with 'ldd -a binary'. That will give you a list of all dynamic objects used by an application, and for each of those dynamic objects the dynamic objects that they depend on. See ldd(1). If your low-level libraries don't show up in that, they are not dynamically loaded. Roland -- R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) pgpAWHZ4rNFFt.pgp Description: PGP signature
