On Mon, 24 Jul 2006, Greg 'groggy' Lehey wrote:
On Friday, 21 July 2006 at 13:29:38 +0200, Dag-Erling Smrgrav wrote:
Tom Rhodes <[EMAIL PROTECTED]> writes:
Wait. I'm lost. Isn't truss(1) broken on FreeBSD?
Depends on your definition of broken. It kind of works provided you have
/proc mounted. Still, there's really not much point in using it; ktrace(1)
is better in almost all respects.
truss is good in that it gives immediate output. I used it recently under
6.1, and I somehow missed that it was broken.
A few things are wrong with truss, none that make it completely broken:
(1) In the past there were a number of reports of problems with race
conditions during truss attach/detach. These reports have entirely
disappeared, as far as I can tell, due to process locking fixes, procfs
fixes, debugging fixes, etc. If they still exist, they should be
investigated, but up-to-date debugging infomation will be needed.
(2) truss relies on procfs, which is known to be evil, and as such, doesn't
work out of the box since we don't mount procfs out of the box. Several
people have worked on enhancing ptrace() so that it can be used to
implement truss, but no one has finished this work. I think the necessary
ptrace() traps now exist for system calls so that this could be done.
(3) truss is believed not to work properly with threaded applications. ktrace
has been extended to know about thread IDs, and has always been able to
generate traces properly for threaded apps, whereas truss likely doesn't
see events from more than one thread (or if it does, it likely gets very
mixed up). It might be good to confirm this.
Robert N M Watson
Computer Laboratory
University of Cambridge
_______________________________________________
[email protected] mailing list
http://lists.freebsd.org/mailman/listinfo/cvs-all
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
