new syscall stub for ia64 linux

[David Mosberger]

>>>>> On Fri, 17 Jan 2003 22:30:37 -0800, Ulrich Drepper <drepper@redhat.com> said:

  Uli> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1

  Uli> David Mosberger wrote:

  >> Is this an OK thing to do?

  Uli> On x86 ld.so doesn't use the new syscall mechanism yet.  Once
  Uli> we have a feature bitmap which is available through AT_SYSINFO
  Uli> the uname syscall can go and we can use the new syscall stuff
  Uli> everywhere.  Do the same for ia64 for now.

I'm not sure I understand how this is supposed to work.  Do you mean
that a word in the AT_SYSINFO page would give you a feature-bitmap?
If so, how does that work with old kernels (where you don't get
AT_SYSINFO) at all, but you still need to know the kernel revision?

BTW: On ia64, the gate page that AT_SYSINFO points to is
"execute-only", so we can't read stuff directly off of it.  Of course
we could have a read-only page, but I don't see the point of wasting a
page given that we can now do (simple) syscalls in ~35 cycles.

	--david