[PATCH] Add biarch support for powerpc64

[Roland McGrath]

> Actually I originally planned to make the ppc64 syscall table different
> from the ppc32 table, leaving out the unimplemented and 32-bit only
> syscalls.

The kernel shares a single table in the source file.  So the correlation of
numbers to names is really not going to vary (just a few of them are only
used on ppc32).  IMHO it is better to print the names in case these
ppc32-only syscalls are used in ppc64.

> There are a lot of places that assume you can read sizeof(long) worth of
> data from the u-area to read a register's contents.  That won't work on
> ppc32 targeting ppc64 whereas it works fine the other way round.

It's really only a small handful of functions that use upeek.  All that
code would use PTRACE_GETREGS64 instead, and that is not much complexity.
It's all the struct decoding that would really be a lot of tedious work.
Anyway, my note was just for future reference and for clarity in our
announcements of what newly works after your changes.  If there were only
the upeek calls to worry about, then I would probably try to talk you into
implementing that.  But I'm not suggesting that now.


Thanks,
Roland