>>>>> On Thu, 10 Feb 2005 13:47:47 +1100, Keith Owens <[EMAIL PROTECTED]> said:
Keith> The problem is that some of the dirty registers will be in
Keith> the original stack, some will be in the MCA stack.
That's OK, libunwind already handles that. The only thing that's
needed to make this work is that ar.bsp/ar.bspstore/ar.rnat are saved
and that those saves properly be described by the unwind-info. The
rest will be automatic. There is one problem though: in pt_regs, we
save the loadrs value instead of ar.bsp. That can't be described at
the moment (the pt_regs code was written long before I knew about
unwind-info...). However, since pt_regs is special anyhow, we can
just handle that in the unwinder, analogous to what we do for
signal-handlers (check_rbs_switch() in libunwind's src/ia64/Gstep.c).
Keith> The preserved registers at the time of MCA/INIT still need to
Keith> be saved so they can be restored on return to SAL. Save the
Keith> preserved registers, set the values that the kernel needs,
Keith> call C code, restore original preserved registers, return to
Keith> SAL. Hmm, I just described struct switch_stack, didn't I?
True. If you really return, then there is no need to even use switch_stack.
You'd just return and that magically restores the preserved registers.
--david
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