Re: Some thoughts on Giant instrumentation

On 28-Feb-02 Glenn Gombert wrote:
> 
> 
>     First a 're-cap' of the various kernel-debugging resources that are
> available and then a couple of suggestions from my own (somewhat limited)
> experience蔊> 
>    There are basically four different types of kernel debugging 'schemes'
> that can be configured with what is commonly available in -Current:
> 
>   (1). Kernel debugging can be done (from user space) using the gdb
> debugging (gdb -k kernelxxx) which can be used to do such simple things as
> examine/set global variables,etc.
> 
> (2). A serial console can be set up (using a remote machine) using the ddb
> debugger, and a kernel compiled on the host machine which had the 'Options
> ddb' and associated 'break_to_debugger' options enabled in the kernel.
>  
> (3). The third is a option to remote (over serial line(s)) perform remote
> kernel debugging using a 'stripped' kernel booted on a second machine and
> running ddb/gdb from two serial consoles on the second (debugging) machine.
> 
> (4). The fourth option is to use a VMware virtual machine (running under
> Current) and use it (as described on the list here at various times) to do
> a versions of 'gdb debugging'. In my experience this arrangement is very
> slow but does have the advantage of using only on pc for as a development
> platform. 
> 
>      I think what needs to be added (and is sorely lacking) are some good
> syscalls (that can be called from 'userland' to perform such things as dump
> out the 'ktr' buffer from a user land program and show contents of some of
> the other kernel parameters (when using a test program from user land). It
> seems like a good set of 'debug syscalls' would be a good addition to the
> smp code that is -current and would make debugging/development efforts
> easier and more efficient for everyone :))

Yep, being able to dump ktr to userland would be rather cool indeed if you'd
like to tackle it. :)

> Glenn Gombert
> [e-mail]
> 

-- 

John Baldwin <[e-mail]>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/

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