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Re: [G++ 4.4.2] ABI changing?
çç <littlesweetmelon@gmail.com> writes:
> I find a problem when upgraded g++ from 4.4.1 to 4.4.2. Original g++
> generates code with "System V ABI", but new g++ generates code with
> "Linux ABI". I don't know what difference between them, but the output
> .so file from g++ 4.4.2 cannot be used in g++ 4.4.1.
>
> To describe my problem clear, I have two x86-64 PCs with RedHat Linux.
> g++ 4.4.1 is installed in PC1, while 4.4.2 is installed in PC2.
> If I copy the executable file compiled by PC1 to PC2, and run "ldd
> a.out", it prints the related modules.
> But if I copy the executable file compiled by PC2 to PC1, and run "ldd
> a.out", it prints error message for "not a dynamic executable".
> Therefore, it seem the gcc tool-chain have backward compatibility for
> "System V" and "Linux" ABI.
>
> Could you tell me why g++ changes ABI? and why cannot I find any thing
> about it from the changelog of gcc 4.4.2?
> Is there a way to specify ABI in gcc command line on x86/64 platform?
This question is not appropriate for the mailing list gcc@gcc.gnu.org.
It would be appropriate for the mailing list gcc-help@gcc.gnu.org.
Please take any followups to gcc-help or to some non-gcc mailing list.
Thanks.
This is actually being caused by the linker, which is not a part of
gcc. The linker marks the ABI in an executable or shared library by
setting the EI_OSABI field in the ELF header, which you can display
using readelf -h. The default value, 0, is known as the "System V
ABI." The GNU linker will set the EI_OSABI field to ELFOSABI_LINUX if
there are any STT_GNU_IFUNC symbols, which are a new feature of glibc.
There is no way to change the linker's behaviour from the gcc command
line.
Ian