Re: Kernel Tracking Question.. regarding kernel and boot files

Hey All,

Please check this. Check this to use Eclipse/Qemu for Kernel
Debugging.
http://issaris.blogspot.com/2007/12/download-linux-kernel-sourcecode-from.html
It was designed to debug linux kernel.

Regards,

Mohammed


On Sun, Apr 10, 2011 at 9:28 AM, Devin Teske <dteske@xxxxxxxxx> wrote:

On Apr 9, 2011, at 9:46 PM, Julian Elischer <julian@xxxxxxxxxxx> wrote:

On 4/9/11 2:51 PM, Chris Richardson wrote:
On Sat, Apr 9, 2011 at 10:34 PM, Chuck Swiger<cswiger@xxxxxxx> wrote:

Hi, Chris--

[ ...Reply-to: set to direct towards the most appropriate list... ]

On Apr 9, 2011, at 8:31 AM, Chris Richardson wrote:
I am totally new to FreeBSD. I was involved within project which
will
trace the kernel. I used ktrace but I could not get appropriate
results
about the files being opened. I don't see any of the boot files
boot0-1
or 2
in the ktrace.out file. Where did they go?
The bootstrap loader stages are what loads and runs the kernel.
ktrace isn't available until afterwards, when the kernel is running.

Is ktrace the best "trace suite" for freebsd kernel?
Kinda depends on what you are doing. Setting up good logging and
making
userland
interfaces for getting to useful information (cf vmstat, ps, iostat,
etc)
is
more likely to be useful over the longer run.


What about if I wanna see the interaction between boot process and
kernel
loading.

either you run it under an emulator that allows you to single step it.
or you just add a lot of printf() to the boot loader.
(some parts are required to fit in small code sizes to adding prints will
cause overflow..)
best to read the docs and then the sources. then it wil become apparent
to you
what you want to find out.

You also have the option of writing Forth modules for the boot-loader. Even
dropping to the "ok" prompt is enough to give you full access to the
built-in Forth interpreter. You can query the variables that are set in the
"environment" (which are different depending whether you've booted via
pxeboot, cdboot, or other method). You can even do some limited device
poking and file-io (both read and write).

The benefit of the forth modules is that you can use it to produce the
necessary debug output whilst avoiding the overflow issue. That is to say,
that one technique I've used is to add code to the loader to export some
string or value of interest to a variable in the environment that I would
then add something like 'echo "debug == $debug"' to loader.rc. Keeps the
loader small and the human fluff off to the interpreter.



What about going through source code .. Is it better to
use Combination of Ecllipse/Qemu and FreeBSD Source tree?
Eclipse is an editor. If you like it in particular, free free to use
it,
otherwise pick something else you'd prefer to use for C code.

I use a combination of vim (as my editor) and CVSweb (URL is in the
handbook) for historical research as necessary.

Just my "tuppence."
--
Devin


Does this method will provide us with someway to see how booting
process
invokes
the kernel to memory ? Any help will be appreciated.
You're asking about the process here:



http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/boot-blocks.html

...? Frankly, none of these are especially big, start by reviewing the
source
code for 'em.


Yeah. this file provides me with the stages in theoretical way. How
about
implementing it using qemu to emulate livecd to see what is going on
boot0.
Do you have an idea about that ?

Good Luck,


Regards,
--
-Chuck



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--
*Mohammed Farrag*
*FreeBSD Contributor*
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