Re: My proposal for the libgcc runtime ABI (ia64 gcc/glibc is broken.)

[Alexandre Oliva <aoliva at redhat dot com>]

On Jul 11, 2000, "H . J . Lu" <hjl@valinux.com> wrote:

> That is how it may be done in libgcc.so. But you cannot do it when
> they are included in libc.so unless you rebuild libc.so. The idea
> is we can easily rebuild libgcc.so without rebuilding libc.so.

I see.

Are you aware that GCC is moving towards creating a shared libgcc?

Why, then, should glibc people take over the creation of this shared
library for GNU/Linux systems?  The GCC maintainers are going to have
to face this problem themselves, probably in a far more complicated
way since we don't care just about GNU/Linux.

Of course, we'll welcome contributions from the maintainers of glibc
with all GNU/Linux-specific knowledge about maintaining shared
libraries and keeping ABI compatibility, but I still feel the burden
of caring about maintaining ABI compatibility and managing library
version numbers can't be delegated to anybody else.  Of course, glibc
people can bug us any time we change an ABI, but glibc people won't be
able to fix any such ABI change except by hacking GCC or introducing
work-arounds that will be specific to GNU/Linux, and that therefore
won't affect users of other platforms GCC maintainers care about.

> On any other system, you may change libstdc++ API and C++ ABI without
> breaking the existing binaries.

What about rebuilding C++ shared libraries with an ABI-incompatible
GCC?  Do you claim this works on all platforms other than GNU/Linux?
I find it hard to believe.

>> more often on GNU/Linux precisely because libc isn't always compiled
>> by the compiler someone who installed their own version of GCC uses.

> The Linux C library is the only C library I know to use the frame based
> exception in gcc.

What I mean is that the problem occurs more often on GNU/Linux because
libc also carries the symbols GCC EH depends upon.  However, I believe
it should affect any other system when you link together shared
libraries created with ABI-incompatible versions of GCC.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist    *Please* write to mailing lists, not to me