Re: kern/43611: kernel-trace (via ktruss) reports wrong parameter/result values

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR kern/43611; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/43611: kernel-trace (via ktruss) reports wrong
 parameter/result values
Date: Wed, 14 Jul 2010 01:45:23 +0000

 On Tue, Jul 13, 2010 at 05:40:04PM +0000, David Laight wrote:
  >  ktruss probably should be rewritten to use system call entry/exit
  >  breakpoints and then userspace controlled reads of the traced programs
  >  memory (which is how truss works on SYSV).
 
 Using ptrace for this purpose is not desirable because it monkeys with
 the parent/child process relationships and tends to break things,
 particularly shell scripts.
 
 (I'm not particularly clear on exactly what ktruss does that's
 different from running kdump afterwards, but then I've never been
 particularly clear on why ktruss is desirable relative to running
 kdump afterwards, either.)
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost