ktrace -d broken on current/stable-9

Garrett Cooper yanegomi at gmail.com
Wed Jan 16 02:55:16 UTC 2013


On Tue, Jan 15, 2013 at 2:53 PM, Jilles Tjoelker <jilles at stack.nl> wrote:
> On Mon, Jan 14, 2013 at 06:48:13PM -0800, Garrett Cooper wrote:
>> I tried using ktrace on a kernel compiled a week ago, and it appears
>> to not be following forks like it should on amd64:
>
>> # ktrace -d ./regress -l
>> [snip]
>
>> Not sure how it broke, but it was working a couple months ago (in
>> particular I remember it working either around October or November),
>> and the bug seems to have worked its way back to 9-STABLE (I'm running
>> into the same problem if I do ktrace -d, enter a shell, then exec
>> another shell from that shell). Haven't spent the time to bisect the
>> commits looking for the culprit (yet), but if need be I'll trace down
>> the culprit sometime this week.
>
>> truss works, so it doesn't seem like ptrace(2) is broken.
>
> ktrace -d is not really useful in the synopsis with a command. It only
> means that the child processes of ktrace (at a time just before it
> executes the utility) should be traced as well. This is almost always an
> empty set, unless you do things like
>   cmd1 & ktrace -d cmd2
> which will trace cmd2 and part of cmd1.
>
> You probably want ktrace -i.

    Dangit -- forgot about that option. Ok, PEBKAC award for me.
Thanks,
-Garrett


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