Re: [Xen-devel] debugging xen ....

Tim Newsham
Wed, 24 Aug 2005 07:30:54 -0000

> After looking around for a howto and asking ppl on IRC, I had to come back
> to the forum for this - how to debug xen?
>
> Basically, I would love to be able to step through the code using gdb
connected
> serially to another machine.
>
> Is there some functionality like that in Xen. I also found some emails
referencing
> a XenDebugger-HowTo, however I couldn''t find that file anywhere.

Run the build script in xen-unstable.hg/tools/debugger/gdb.
Install the gdbserver and gdb (I put them in /usr/local/bin
   as gdbserver-xen and xengdb).
Build your kernel with debug.  I use the flags
   "verbose=y domu_debug=y debug=y".  although I dont know if these
   are all required.
Start up your domain (I use vm-tools and do all the steps except
   the vm-pause step).
Run gdbserver.  I run "gdbserver-xen 127.0.0.1:9999 --attach $dom"
Run gdb.  I run "xengdb -x remgdb" where remgdb has the command
   "target remote 127.0.0.1:9999" in it.

Tada, you''re in a debugger.

I use the following script to automate this tedious process:

--- deb.sh ---
#!/bin/sh

run()
{
         echo "$*"
         $* || (echo ''failed''; exit 1)
}

# vm-create isnt giving us the right answer...
dom=`vm-create`
echo dom is $dom

run vm-memory -m $dom 64m
run vm-memory -i $dom 64m
run vm-build.linux $dom /root/kernel

echo done $dom
gdbserver-xen 127.0.0.1:9999 --attach $dom &
sleep 1
xengdb -x /root/remgdb

run vm-pause -u $dom
--- end deb.sh ---

> Himanshu Raj
> PhD Student, GaTech (www.cc.gatech.edu/~rhim)

Hope this helps,
Tim Newsham