RE: Question about kernel module debug

[Yuxin_Zhuang at emc dot com]

Configuration of my environment:
Machine architecture:	i686
OS: 	RHEL4 with kernel 2.6.9-42.Elsmp
Systemtap version:	0.6
Elfutils :	0.129
GCC:	3.4.6

The content of the script
**************************
probe module("my_module").function("*")
{
	printf( "In the module\n");
}
**************************

The output is as follows:
**************************
Pass 1: parsed user script and 25 library script(s) in 80usr/10sys/136real ms.
semantic error: cannot find module my_module debuginfo: r_offset is bogus
semantic error: no match for probe point
while: resolving probe point module("my_module").function("*")
Pass 2: analyzed script: 2 probe(s), 0 function(s), 0 global(s) in 0usr/30sys/43real ms.
Pass 2: analysis failed.  Try again with more '-v' (verbose) options.
**************************

And the functions in kernel and modules built with the kernel can be probed with no problem.
The module 'my_module' has been built with the debug information not stripped. But systemtap is still looking for a '.ko.debug' file.

Thanks !
ZHUANG Yuxin

-----Original Message-----
From: systemtap-owner@sourceware.org [mailto:systemtap-owner@sourceware.org] On Behalf Of Frank Ch. Eigler
Sent: 2007年10月19日 2:22
To: Yuxin, Zhuang
Cc: systemtap@sources.redhat.com
Subject: Re: Question about kernel module debug

Yuxin_Zhuang@emc.com writes:

> What do you mean by " There should be no need for the .ko.debug file
> if the basic .ko file was not stripped. "??  Does it means that
> systemtap will get the debug information from the .ko file and will
> not look for the .ko.debug file on the three search paths??

That's right.

> But when the .ko.debug symlink is removed, the result of strace
> shows that without finding the '.ko.debug' file on the three search
> paths systemtap just fails. Saying 'r_offset is bogus'.

That's not right (elfutils error DWFL_E_BADRELOFF).  It's as if
something has corrupted the data.  Please describe the toolchain
version, architecture, and anything else that may be unusual about the
build process.

- FChE