Re: Help debugging domain builder, qemu upstream and hvmloader

[Wei Liu <liuw@liuw.name>]

On Wed, 2011-07-27 at 12:53 +0900, Daniel Castro wrote:
> Hello All,
> 
> I run into this problem when I modify seabios.
> (XEN) hvm.c:1131:d13 Triple fault on VCPU 0 - invoking HVM system reset.
> 
> Since there is no fault handlers in the early stages of guest boot I
> am in the need to debug the domain builder, upstream qemu and/or
> hvmloader to see where exactly the fault is being generated.
> 
> I have no experience on debugging and this seems like a good time to start.

Ian Campbell once mentioned his trick to debug QEMU (following
paragraphs quoted from his email):

=====================================================================
When I have an issue with qemu I often specify the device model in my
guest configuration as a script containing:
       echo $@ > /tmp/qemu-dm
       sleep 1h

Then immediately after running "xl create" I can examine /tmp/qemu-dm
and run the qemu by hand in the foreground, or under gdb etc. (there is
a timeout in xl waiting for qemu to announce itself so you need to be
reasonably prompt...)
=====================================================================

Wei.