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

[christos%zoulas.com@localhost (Christos Zoulas)]

On Jul 13,  5:40pm, david%l8s.co.uk@localhost (David Laight) wrote:
-- Subject: Re: kern/43611: kernel-trace (via ktruss) reports wrong parameter

| 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).

Well, this is PT_SYSCALL and /usr/pkg/bin/strace :-)

christos