[ipxe-devel] [gPXE] Debugging over UDP

Michael Brown mbrown at fensystems.co.uk
Wed Dec 8 19:24:40 UTC 2010

On Wednesday 08 Dec 2010 18:58:11 Vinay Venkataraghavan wrote:
> I just recently started to play with gPXE and would like to step through
>  the process using the debugging options. But I have not been sucessful.
>  Any help would be appreciated.
> The steps I followed are as show below:
> 1. Built an iso image and burned it to a dvd.
> 2. Booted the client machine and broke into the gPXE prompt.
> 3. Executed: ifopen net0
>                    set net0/ip
>                       bdgstub udp net0
> 4. On the debugger machine.
>                 gdb
>                 set debug remote 1
>                 file bin/gpxe.lkrn.tmp
>                 target remote udp:
> Questions:
> 1) What is the name of the corresponding .tmp file to use when I am using
>  an gpxe.iso image. This is not specified in the gPXE documentation.

You want the ".lkrn.tmp" file.  (An .iso image is built using the .lkrn 

> 2) I get the following output:
> <snip>

Are you able to ping from the machine running gdb?

Also, since you say that you just recently started to play: are you aware that 
there is a substantial amount of built-in debug code that can be enabled 
without having to go to the effort of using gdb?  For example, if you are 
having problems with DHCP, then

  make bin/ipxe.iso DEBUG=dhcp

will show you debugging messages related to DHCP.  You can find some 
description of debug builds at




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