running 5.1-RELEASE with no procfs mounted (lockups?)

[John Baldwin]

On 18-Jul-2003 Terry Lambert wrote:
> Pawel Jakub Dawidek wrote:
>> +> truss                Relies on the event model of procfs; there have been some
>> +>              initial patches and discussion of migrating truss to ptrace() but
>> +>              I don't think we have anything very usable yet.  I'd be happy to
>> +>              be corrected on this. :-)
>> 
>> Hmm, why to change this behaviour? Is there any functionality that
>> ktrace(1) doesn't provide?
> 
> It can interactively run in another window, giving you realtime
> updates on what's happening up to the point of a kernel crash.
> With ktrace, you are relatively screwed.
> 
> Another good example is that it dump out information that ktrace
> can't, because of where it synchronizes.  Some people recently
> have been seeing "EAGAIN" when they haven't expected it, with
> the process exiting immediately after that, with no real clue
> as to where in the code it's happening (e.g. which system call);
> truss will show this, if run in another terminal window, but
> ktrace will not (yes, I know it should; it doesn't.  If you can't
> reconcile this with how you think ktrace should work, then fix it).

Since ktrace logs all syscall entries and exits, it should seem that
a kdump after the process had exited would show which syscall returned
EAGAIN quite easily.

-- 

John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/