[lug] Kernel Level Debug Tools

[Ian S. Nelson]

Jonathan Corbet wrote:

>>.What kernel level debug tools are available .... interested in what
>>experiences others have had also with the tools, and how they rate them as
>>to
>>effectiveness, usability, etc.
>>    
>>
>
>It depends on what you're trying to do.  Somebody else already mentioned
>the debug chapter in Linux Device Drivers, (available online at
>http://www.xml.com/ldd/chapter/book/ch04.html), so I don't have to do
>that...:)
>
>The one thing I might add is that, for certain kinds of work, User-mode
>Linux is seriously great stuff.  With UML, you have a kernel running as a
>regular process, and you just hit it with gdb in the usual way.  Great for
>things like filesystems; not so good for stuff that has to work with real
>hardware. 
>
>jon
>

It depends on what your'e trying to debug at the kernel level.  I've 
been very productive with a post card and a logic analyzer.  When you 
can't trust anything, you can usually trust post codes.

I've played with kgdb and kdb some.  kgdb is extremely cool but it seems 
to screw up things enough that by the time you need a kernel debugger 
kgdb makes the problem go away by tweaking the timing.  kdb is 
remarkably useful too.  Lower level and kind of a pain at times but it 
can really help find those odd ball problems.

Ian