[hppa-linux] syscall work

[Mike Shaver]

Cary Coutant wrote:
> I'd suggest *not* using the same gateway page address as HP-UX. If you
> do, you won't be able to develop a later kernel extension to support
> HP-UX binaries, unless you allocate syscall numbers carefully.

Well, my plan was to do what the MIPS guys have done (and others, like
maybe SPARC?): 
syscall numbers 0 to 200-something are __NR_HP_syscall, and then the
Linux ones start at 1000.  HP-UX binary emulation is something that I
really really want early on, because it will give us a functioning
userland while we're trying to get compiler and linker and glibc ports
complete and working.

But maybe you're right -- maybe we use one gateway page address for
HP-UX compat, and another for native-Linux syscalls.  We have a lot more
flexibility in our system call mechanism than the other platforms did, I
think, so perhaps there's a better way.

It'd be nice to have hpux.o as a module for binary compatibility, when
we get there, but that's probably not so hard.  Ponder...

The checked-in unistd.h has appropriate syscall numbering to support the
current plan, if you'd like to peek.

Mike

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