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Re: PPC startup code
Roland McGrath <roland at redhat dot com> writes:
> > Given that the calling sequence is in fact defined in the ABI spec, I
> > think we probably shouldn't change it without a really good reason.
>
> This makes it sound like it's part of a formal spec, which it's not. The
> registers at startup are part of the ELF ABI spec. But __libc_start_main
> and its calling sequence are just part of the glibc ABI, which can and does
> change between glibc releases. There is just the set of practical issues I
> mentioned with the part of the ABI involving crt1.o changing, which is rare
> but not intrinsically different from other glibc ABI changes that are fine.
However, you still need to provide compatibility code so that
executables that contain the old crt1.o can still run. In practise,
this means that changing an ABI just to "clean up glibc" doesn't work;
things just get worse because now you have both the old ABI *and* the
new ABI to support.
--
- Geoffrey Keating <geoffk at geoffk dot org>