serial debugging - dumb question

[Greg 'groggy' Lehey]

On Thursday,  8 April 2004 at 14:57:22 -0400, Andrew Atrens wrote:
>
> Hi Folks,
>
> I guess I should apologize first before you read any further, for the
> dumbness of this question ....
>
> I've got a few 4.x systems kicking around, and at the moment have one hooked
> via serial port to my dragonfly box. I was hoping to use it to help debug
> some lockups I'm seeing...
>
> Not sure if this is possible or if I'd need to convert it to DragonFly
> first...

If you're concerned about whether you can use FreeBSD gdb to debug a
DragonFly kernel, I think you don't need to worry.  I've used it to
debug NetBSD and Linux as well; DragonFly should be no problem at all.

> On the Dragonfly box I break to ddb, and type 'gdb' and then 'c' to
> continue. Then I break to ddb again and it tells me that it's received
> the break and I assume is now chatting on the serial port ...
>
> On the 4.x (4.10beta) box, I see -
>
> $ gdb -k
> ...
> (kgdb) target remote /dev/cuaa0
> Remote debugging using /dev/cuaa0
> Ignoring packet error, continuing...
> (etc)

This is a typical communication error.  It certainly doesn't relate to
any potential compatibility issues between FreeBSD and DragonFly.

> Not sure if I should be using the ttyd0 instead of cuaa0, or perhaps
> something else entirely different?

cuas0 should be right, unless you meant to say cuaa1 :-)

> Not 100% sure about my cable either, I just grabbed it out of a big
> box of random cables in our lab ... It *looks* like a good cable.

There are plenty of good cables.  It's not clear that this is the
*correct* cable.

> Could I perhaps also be using the wrong baud rate ?

Yes.

> Any help our pointers to help would be greatly appreciated ..

I'd start by trying to set up a cu or tip connection between the two
boxes.  This is described in my (eternal draft) kernel debugging
tutorial.  You can find the latest version at
http://wwww.lemis.com/papers/Taiwan/tutorial.pdf (the name is because
I did it at the AsiaBSDCon last month), specifically round page 34.
Let me know if you have any problems.

Greg
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