Add support for alternative break-to-debugger support on the Xen console. This should help debug boot-time hangs experienced in 9.0-BETA.
Add support for alternative break-to-debugger support on the Xen console.
This should help debug boot-time hangs experienced in 9.0-BETA.

MFC after:	3 weeks
Tested by:	sbruno
Approved by:	re (kib)

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase