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RE: Question about kernel module debug


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??
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'.

-----Original Message-----
From: systemtap-owner@sourceware.org [mailto:systemtap-owner@sourceware.org] On Behalf Of Frank Ch. Eigler
Sent: 2007年10月16日 23:58
To: Yuxin, Zhuang
Cc: systemtap@sources.redhat.com
Subject: Re: Question about kernel module debug

Yuxin_Zhuang@emc.com writes:

> I've installed systemtap 0.5.8 on RHEL4 with kernel 2.6.9-42. 

This is over a year old.  If you can, please upgrade to a later
systemtap build.  RHN should have 0.5.12 or even 0.5.14 by now.

> [...]  1. Is the 'debuginfo' of the module needed by systemtap is
> just the stuff created by gcc with option '-g'?

Yes.

> Will an additional '-O2' make a lot of difference?

It will make the debugging information somewhat less precise, giving
you fewer useful probe points.

> 2. I've put the '.ko' file which is built with options '-g -O2' under
> the proper search path and created a symbol link with the suffix
> '.ko.debug' to it. [...]

There should be no need for the .ko.debug file if the basic .ko file
was not stripped.  What does "readelf -S module.ko" say about .debug_*
sections?

- FChE


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