Re: [RFC PATCH 0/4] utrace: new modular infrastructure for user debug/tracing

From: Chuck Ebbert
Date: Thu Jun 15 2006 - 19:02:52 EST


In-Reply-To: <20060613231000.38B76180072@xxxxxxxxxxxxxxxxxxx>

On Tue, 13 Jun 2006 16:10:00 -0700, Roland McGrath wrote:

> I have been working on for a while, and imagining for much longer,
> replacing ptrace from the ground up. This is what I've come up with so
> far, and I'm looking for some reactions on the direction.

At least three different sets of people want to extend the syscall
tracing. Jeff Dike posted a patch that lets you supply a bitmask of
syscalls to trace. Renzo Davoli posted one that lets you decide, after
trapping entrance to a syscall, whether to skip the trap that would
normally be done on exit from the same call. Charles P. Wright also
had a similar patch. I think this needs to be done at the utrace
level -- a tracing engine couldn't add that on its own (could it?)

Renzo Davoli also posted a patch to allow "batching" of ptrace requests
and Systemptap really needs this, too. AFAICT this can be done by writing
a custom engine.

And BTW patches 1 and 2 never made it to the list. The ones on your
server (http://redhat.com/~roland/utrace/) don't apply cleanly due to
whitespace damage but that can be fixed by stripping trailing whitespace
from the kernel files patch(1) complains about.

--
Chuck
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