Re: [ANNOUNCE] Merkey's Kernel Debugger

From: Nick Piggin
Date: Wed Aug 06 2008 - 01:50:44 EST


On Wednesday 06 August 2008 13:08, Andi Kleen wrote:
> Nick Piggin <nickpiggin@xxxxxxxxxxxx> writes:
> > Seriously? Because it doesn't seem to have had enough peer review,
> > it hasn't had widespread testing in somewhere like linux-next or
> > -mm, and we already have kgdb so you have to also explain why you
> > can't improve kgdb in the areas it trails mdb.
> >
> > But the ideal outcome would be if you could contribute patches to
> > kgdb to the point where it is as good as mdb. It is already in the
>
> I don't think kgdb and a simple assembler debugger
> are directly comparable. kgdb always requires a remote machine,
> which has many advantages, but is also often very inconvenient
> or impossible to arrange. An low overhead assembler debugger
> can be always compiled in just in case.
>
> Also at least for the x86 port the debugger interfaces should
> be general enough now (see die hooks as a "debug vfs") that it would
> be quite possible to have a multitude of debuggers just using
> them. In fact that's already the cases, kprobes and kgdb and
> kdump are all kinds of debuggers using such hooks.
>
> As long as it doesn't impact the core code and the mdb
> code itself is considered merge worthy and has clean interfaces
> that would seem fine to me.It essentially would just live somewhere in
> its own directory using the existing interfaces. My standard
> test for seeing if a debugger has clean interfaces is to see
> if it can be loaded as a module.
>
> There are enough different debugging styles around that offering
> developers different tools of which they can pick whatever suits
> them is not a bad idea. Also as everyone knows debugging
> is often a major time eater and if more tools are available that
> can only help the kernel.
>
> That said I haven't read the mdb code, not judging on its general
> merge-worthiness or am really completely sure what are all the details
> of a "netware style debugger", just a general high level comment on
> debuggers. At least judging based on the patch sizes it at least
> doesn't seem particularly bloated. But of course it would need full
> proper review first.

OK thanks for the info. I don't actually know debugger code as I
said, so I wasn't against merging mdb if it offers things that
kgdb fundamentally cannot.

If so, then ensuring clean interfaces indeed would seem like a
good first step to getting it merged.
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