DomU & HVM GDB server for 32-bit (PAE and non-PAE) and x86_64 systems
----------------------------------------------------

Lines marked below with [*] are optional, if you want full
source-level debugging of your kernel image.

To build the GDB server:
 0. Build rest of the Xen first from the base directory
 1. Run ./gdbbuild from within this directory.
 2. Copy ./gdb-6.2.1-linux-i386-xen/gdb/gdbserver/gdbserver-xen
    to your test machine.

To build a debuggable guest domU kernel image:
 1. cd linux-2.6.xx-xenU
 2. make menuconfig
 3. From within the configurator, enable the following options:
    # Kernel hacking -> Compile the kernel with debug info [*]
                     -> Compile the kernel with frame pointers
 4. (Re)build and (re)install your xenU kernel image.

To debug a running guest:
 1. Use 'xm list' to discover its domain id ($domid). 
 2. Run 'gdbserver-xen 127.0.0.1:9999 --attach $domid'.
 3. Run 'gdb /path/to/vmlinux-syms-2.6.xx-xenU'.
 4. From within the gdb client session:
    # directory /path/to/linux-2.6.xx-xenU [*]
    # target remote 127.0.0.1:9999
    # bt
    # disass

To debug a crashed domU guest:
 1. Add '(enable-dump yes)' to /etc/xen/xend-config.sxp before
    starting xend.
 2. When the domain crashes, a core file is written to
    '/var/xen/dump/<domain-name>.<domain-id>.core'.
 3. Run 'gdbserver-xen 127.0.0.1:9999 --file <core-file>'.
 4. Connect to the server as for a running guest.