* Frank Ch. Eigler <f...@redhat.com> wrote:
> Hi -
>
> On Tue, Dec 01, 2009 at 05:11:32PM +0100, Ingo Molnar wrote:
>
> > Those facilities are not overlapping with kgdb though so my point
> > doesnt apply to them. An in-kernel gdb server sure overlaps/extends
> > kgdb though.
>
> Only in name. One is highly invasive, for debugging the kernel across
> serial consoles. The other is highly noninvasive, for debugging user
> processes across normal userspace channels. They both happen to talk
> to gdb, but that's the end of the natural "overlap".
>
> Even if kgdb was extended to be able to manage userspace, and if gdb
> itself was extended to be able to use that same single channel, this
> would still not duplicate the use scenario for an ordinary user
> debugging his own processes.
>
> (Plus, in the future where at least gdb is applied toward kernel+user
> debugging, it is unlikely to be the case that this would need to be
> done *over a single channel*. A separate channel for kernel and
> separate channels for userspace programs are no less likely.)
Well nothing that you mention here changes our obvious suggestion that
an in-kernel gdb stub should obviously either be a kgdb extension, or a
replacement of it. We dont want to separate facilities for the same
conceptual thing: examining application state (be that in user-space and
kernel-space).
> > Btw., perf does meet that definition: it functionally replaces all
> > facilities that it overlaps/extends - such as Oprofile. [...]
>
> (And they currently separately coexist.)
You didnt get my point apparently. Keeping the overlapped facility for
compatibility (and general user inertia) is fine. Creating a new
facility that doesnt do everything that the existing facility does, and
not integrating it either, is not fine.
Which was both Peter's and my point really.
Ingo
