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

[David Laight <david%l8s.co.uk@localhost>]

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

From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/43611: kernel-trace (via ktruss) reports wrong 
parameter/result values
Date: Tue, 13 Jul 2010 18:40:14 +0100

 On Tue, Jul 13, 2010 at 12:35:00PM +0000, 
Wolfgang.Stukenbrock%nagler-company.com@localhost wrote:
 > >Synopsis:       kernel-trace (via ktruss) reports wrong parameter/result 
 > >values
 ...
 >      While debugging a tape-device problem we have traced the dd(1) command 
 > in order to validate the correct system calls.
 
 ktrace+kdump tends to work much better than ktruss.
 
 ktruss tries to convert the ktrace data to system call parameters and
 fails when the data is unexpected (due to extra traces).
 
 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).
 
        David
 
 -- 
 David Laight: david%l8s.co.uk@localhost