[PATCH] ppc64 utmp changes

[Roland McGrath]

> That we certainly can't. We have to keep it for Alpha and IA-64 for sure.

Right, the always-64 platforms.  I would be happier with a new sysdeps
macro for 64-bit platforms saying whether they have 32-bit-compatible file
formats, just defined in some other file, and not having bits/utmp{x,}.h
copied.  It could be a macro just about utmp in an extra tiny bits/ header,
or it could be in bits/wordsize.h something like __WORDSIZE_COMPAT32 and
perhaps be used by other such cases if they come up. i.e.

#if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32
struct { __int32_t ... }
#else
struct timeval ...;
#endif

> I think we can not-too-painfully change it for sparc64.
> Dunno about x86-64 and s390x.

It's sounding like everyone is saying that breaking the existing 64-bit
file formats for all these platforms is ok.  Either people just don't care,
or those file formats have never really been used by 64-bit programs.  If
either of those is so, does that mean that noone cares about or ever used
the various struct utmp-using ABIs either?  Can we really change these ABIs
(the size and layout of struct utmp) without versioning?