[RFC/RFA/hppa] unwind pc in bottom frame using correct register

[Randolph Chung]

> Almost works. We get the first frame right, but then the backtraces
> are broken because we get identical frames. This sort of makes sense
> to me, since once you are past frame 0, you know which register to
> unwind by inspecting the function associated to the frame (either prologue
> analysis, or using the unwind info, or ...). No? So I would venture
> that the SS_INSYSCALL thingy might be specific to the innermost frame?

hrm, yes.... you are right.

> > the bit about HPPA_FLAG_REGNUM seems to be an hpux specific thing. I
> > think the syscall stub does something special so we try to return r31
> > instead of pcoqh. I haven't looked at this in detail...
> 
> If it's HP/UX specific, it must be hurting hppa-linux?

well, on hppa-linux the "flags" register is always 0, so we always read
pcoqh.

as you said i think we need to first better understand what is this
SS_INSYSCALL thing....

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/