Red Hat Bugzilla – Bug 74781
compat-egcs needs better documention on usage
Last modified: 2007-04-18 12:46:58 EDT
From Bugzilla Helper: User-Agent: Mozilla/5.0 Galeon/1.2.5 (X11; Linux i686; U;) Gecko/20020606 Description of problem: When compiling and linking a shared library module which references semctl and/or shmctl, the compat-egcs package produces a shared library with dependencies on glibc 2.2, so that the library can't be used on RedHat 6.2. On RH 6.2, nm produces the following output: [~] nm libfoo.so | fgrep GLIBC_2.2 U semctl@@GLIBC_2.2 U shmctl@@GLIBC_2.2 Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. Write a C file with a function that reference semctl or shmctl. 2. Compile the C file, and link it into a shared library with egcs after running the compat-egcs compatibility script. 3. Run nm on the shared library to see the symbols. Actual Results: The shared library references GLIBC 2.2 versions of semctl and shmctl. Expected Results: The shared library should have referenced either unversioned or GLIBC 2.1 (or GLIBC 2.0?) versions of semctl and shmctl. Additional info:
After a day and a half of experimentation, I've come to the conclusion that compat-egcs is ... seriously confusing. :) The only way I could create shared libraries and executables that worked well on Red Hat 6.2 was to do the following: 1) run /usr/i386-glibc21-linux/bin/i386-glibc21-linux.sh to set the LDEMULATION and GCC_EXEC_PREFIX environment variables correctly. 2) compile and link with gcc 2.96 driving, *not* with egcs. So with a simple program, I'd compile as follows: gcc -c test.c 3) When compiling C++ programs, I found that gcc 2.96 was not passing a flag that the egcs subprograms expected, namely __cplusplus. So when compiling a C++ program, I have to do: g++ -D__cplusplus test.c and then... 4) I found that I have to actually use gcc 2.96 to link, *not* egcs as I had expected. The latter simply fails to work because it's using the wrong object files/libraries when compiling. So again, the possibilities might be: gcc -o test test.o gcc -shared -o libtest.so test.o gcc -shared -o libtest.so test.o -lstdc++ g++ -shared -o libtest.so test.o All of this leads me to wonder whether compat-egcs has been thoroughly tested (never mind that it's completely undocumented...). Have I come to the correct conclusions, or not?
Or... just use i386-glibc21-linux-gcc and i386-glibc21-linux-c++. I shoulda guessed. Or should I have? Can someone write documentation for this stuff, please?
compat-egcs is not included in the distribution any longer.