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Re: RFC: threads PREPARE_TO_PROCEED patch
On Sat, Mar 15, 2003 at 09:39:14PM +0100, Mark Kettenis wrote:
> Date: Fri, 14 Mar 2003 13:35:29 -0500
> From: Daniel Jacobowitz <drow at mvista dot com>
>
> > I'm not quite sure whether changing the gdbarch default is a good
> > idea, but replacing lin_lwp_prepare_to_proceed with
> > generic_prepare_to_proceed has been the intention all along.
>
> Well, let me describe the problem I'm trying to solve; I'd like your
> opinion on how to approach it. When using gdbserver, we need to have
> generic_prepare_to_proceed. Not the lin_lwp version, and not the
> "default" one from arch-utils. The former won't work and the latter
> doesn't do enough. So cross debuggers need to pick this up.
>
> OK, but generic_prepare_to_proceed() is perfectly usable on a native
> GNU/Linux GDB too, isn't it?
Yes, exactly.
> Note that this is a property of the target. Not of the architecture.
> I'm not sure PREPARE_TO_PROCEED belongs in gdbarch at all. It's only
> defined by Mach3, HP/UX, and Linux; it's undefined for x86-64-linux
> (why???). I could set it in all the Linux gdbarch init functions that
> I care about, but that doesn't seem like much of a solution.
>
> It seems to be a property of the OS to me. In its current
> incarnation, gdbarch does includes details of both the architecture
> (ISA) and the OS (OS/ABI). So gdbarch seems to be the correct place
> for PREPARE_TO_PROCEED to me. So yes, I think you should add it to
> all relevant Linux gdbarch init functions.
I can do that; I'll put a patch together.
But I must admit that I don't really agree. It seems to be a property
of the threads implementation for the target instead. Consider this
case: if someone wanted to write a remote protocol stub for HP/UX.
They wouldn't want the HP/UX version of PREPARE_TO_PROCEED naturally,
since that's native-only. They'd want most likely
generic_prepare_to_proceed. The default function isn't useful; it
doesn't support switching threads correctly.
(Incidentally, from reading the HP/UX implementation, I believe that
using generic_prepare_to_proceed would work there too. It wouldn't
work for the Mach 3.0 implementation as-is but I think it could be made
to work. I'm not volunteering; are either hppa*-*-osf* or
mips*-*-mach3* still living? Perhaps we should deprecate them next
release.)
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer