Re: kgdb in emacs

[Sanjeev Kumar.S]

I will answer your questions from the beginning:

> When can you use gdb -k?
> With the latest GDB from CVS, I get:
> $ gdb -k
> gdb: unrecognized option `-k'
I believe in newer versions of bsd release we've moved from 
"bsd -k" to  kgdb. I don't know why this decision was made. Maybe
its for some simple reason but I haven't poked around it.
> Run gdb ( like this ) : kgdb -a -a -a kernel.debug
> (kgdb) target remote  /dev/cuad0

kgdb requires either a core file or a device file for remote
debugging. If we issue this command on a local machine this
behavior is pretty straightforward, with no quirkiness.

> I guess you mean Emacs now parses your command line now.

> But presumably you still get *gud-cuad0* in the mode-line of the GUD
> buffer.
Yes. I get the above, but is that an issue ? 

> Does kgdb work like gdb?
yes
 it works like gdb. In its full glory.

> Is "target remote  /dev/cuad0" a valid kgdb command?

Again, I was not able to get to this point without specifying the 
complete set of arguments while starting. ie. to start i need to specify
-r and the debug file. without that i was not able to start it up.

> Run gdb ( like this ) : kgdb -a -a -a -r /dev/cuad0 kernel.debug

Just -a works for me. "-a -a" or "-a -a -a" and I get some garbled output
on the screen. But still I have an issue, I have to press a "n" or "s" to
get emacs to display the source file. Any way around it ?

> One last thing, if you do get it to work well, please e-mail me what you
> have learnt so that I can add it to my homepage.

Yes...I will do this. I will make a complete document and give one copy
to you and one to the Freebsd doc team. But I will try and get as much
questions resolved in the document, so no one has to waste almost
a
 day figuring it out like me. 

Regards,
Sanjeev.

Nick Roberts <nickrob@snap.net.nz> wrote:
>   > Thank you very much Nick, Your clue of emacs version prompted me
>  > to upgrade my emacs. after which I'm able to do it.
>
> I guess you mean Emacs now parses your command line now.
>
> But presumably you still get *gud-cuad0* in the mode-line of the GUD
> buffer.
>
>  > BTW,  my earlier emacs version was 21.2.4 and now it is 22.0.50.1
>  > 
>  > One more question: I'm still not able to open the file another emacs
>  > window. I thought this was supposed happen automatically. In other
>  > instances of emacs ( like when debugging apps ) the source code file
>  > opens automatically in another emacs window ( vertical split style).
>
> I have some more thoughts but you need to answer my
>  questions for good
> communication.
>
> Does kgdb work like gdb?
> Is "target remote  /dev/cuad0" a valid kgdb command?
>
>  > Even if it doesn't, when I enter "f" it opens up automatically.
>
> For the source to appear gdb/kgdb must output annotations.  In gdb, this
> requires "--fullname" or "-annotate=1" for text mode and "-annotate=3"
> for graphical mode.  In Emacs 21 "--fullname" was used but was not visible
> to the user.
>
> In Emacs 22, running an app like this:
>
>   Run gdb (like this): gdb myprog
>
> won't display the source, but:
>
>   Run gdb (like this): gdb -annotate=3 myprog
>
> will.  Likewise, I suspect
>
>   Run gdb ( like this ) : kgdb -r /dev/cuad0 kernel.debug
>
> won't display the source, but:
>
>   Run gdb ( like this ) : kgdb -a -a -a -r /dev/cuad0 kernel.debug
>
> will.
>
>  > One possibility is, though i changed the emacs current directory
>  > to /usr/obj/usr/src/sys/MYKERNEL/ , the -r
>  /dev/cuad0 option would have
>  > changed the default directory, as evident in the file line when a gud
>  > window is opened:
>  > Current directory is /dev/
>  > :(
>
> You really want to find another way of specifying the arguments along the lines
> that I suggested, so that the directory doesn't change and you get
> *gud-kernel.debug* in the mode-line of the GUD buffer.  However, I think
> another way to stop the current directory from changing is to set
> gud-chdir-before-run to nil.
>
> One last thing, if you do get it to work well, please e-mail me what you
> have learnt so that I can add it to my homepage.
>
> Thanks,
>
> Nick                                           http://www.inet.net.nz/~nickrob

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