XenDebugger-HOWTO

XenDebugger-HOWTO

[Ryan Harper]

I've been trying to get the XenDebugger running on the unstable tree.
After compiling xen with debugging=y ( and some patches ), I started
following the XenDebugger-Howto, but something is missing.

How does nsplitd connect to the serial line going into Xen?

Looking at the diagram entitled Setup:

Setup
-----

 +-------+ telnet +-----------+ serial +-------+
 |  GDB  |--------|  nsplitd  |--------|  Xen  |
 +-------+        +-----------+        +-------+

it would seem that nsplitd connects a gdb-telnet session to the serial
connection into Xen running with pdb on.  However, if you examine
nsplitd code there is nothing related to serial at all, just sockets.

Looking further into the howto, I set up my xinetd conf as instructed
and added the two lines to /etc/services:

hostname$ egrep 'wcons00|nsplit1' /etc/services
wcons00         9600/tcp        # Wanda remote console
nsplit1         12010/tcp       # Nemesis console splitter ports.

What is the Wanda remote console?  

I'm guessing that Wanda is the missing piece that connects the local
serial port to the network.  If so, where is Wanda?  And if not, what am
I missing that connects the network connection (gdb telnet) to the
serial line into xen?

Ryan Harper


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Re: XenDebugger-HOWTO

[Kip Macy]

nsplitd allows you to use one serial port for both the debugger and the
console. It multiplexes the two by setting the high-bit on one and not
the other.

Sample - machine is named 'larry'
from /etc/services:
shemp0          6056/tcp                        # shemp console
shempnsplit     12016/tcp                       # shemp nsplit service

6056 is the port on the actual console server - 12016 is the port I
connect to on this machine to connect to the console

from /etc/xinetd.d/nsplit:

  service shempnsplit
  {
        socket_type             = stream
        protocol                = tcp
        wait                    = no
        user                    = root
        server                  = /usr/sbin/in.nsplitd
        server_args             = raidqa-cpt1:shemp0
        disable                 = no

  }


raidqa-cpt1 is the name of the console server -


I connect to shemp's console by on larry 12016, I connect gdb with
(gdb) target remote shemp:2345


Just to warn you. I've found PDB to be completely broken for the past
four months. If you get it to work, let me know what your setup is. If
you are debugging DOM0 or xen, it is pretty much your only option. If
you are debugging a guest, my debug patches work *much* better.



					-Kip






On Mon, 17 Jan 2005, Ryan Harper wrote:

> I've been trying to get the XenDebugger running on the unstable tree.
> After compiling xen with debugging=y ( and some patches ), I started
> following the XenDebugger-Howto, but something is missing.
>
> How does nsplitd connect to the serial line going into Xen?
>
> Looking at the diagram entitled Setup:
>
> Setup
> -----
>
>  +-------+ telnet +-----------+ serial +-------+
>  |  GDB  |--------|  nsplitd  |--------|  Xen  |
>  +-------+        +-----------+        +-------+
>
> it would seem that nsplitd connects a gdb-telnet session to the serial
> connection into Xen running with pdb on.  However, if you examine
> nsplitd code there is nothing related to serial at all, just sockets.
>
> Looking further into the howto, I set up my xinetd conf as instructed
> and added the two lines to /etc/services:
>
> hostname$ egrep 'wcons00|nsplit1' /etc/services
> wcons00         9600/tcp        # Wanda remote console
> nsplit1         12010/tcp       # Nemesis console splitter ports.
>
> What is the Wanda remote console?
>
> I'm guessing that Wanda is the missing piece that connects the local
> serial port to the network.  If so, where is Wanda?  And if not, what am
> I missing that connects the network connection (gdb telnet) to the
> serial line into xen?
>
> Ryan Harper
>
>
> -------------------------------------------------------
> The SF.Net email is sponsored by: Beat the post-holiday blues
> Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek.
> It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
>


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Correction Re: XenDebugger-HOWTO

[Kip Macy]

Man am I out of it.
>
>
> I connect to shemp's console by on larry 12016, I connect gdb with
> (gdb) target remote shemp:2345

I connect to shemp's console by 'console_client.py larry 12016' - I
connect to the stub from gdb with 'target remote larry:12017'



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