[j-nsp] RE switch master to backup

[Chris Adams]

Once upon a time, Ross Halliday <ross.halliday at wtccommunications.ca> said:
> On Sun servers there used to be a way cool method to get them to reboot: Send a trillion BREAKs over the console. Same thing could happen if you rebooted your console device a few times, or, indeed, if the cable was bad. I'm not sure if JUNOS operates like this internally, but as they have common BSD roots it could be related.

That was related to OpenFirmware serial console behaivor, which would be
unrelated to the Juniper BIOS (for x86 systems) or U-Boot (for the
other) behavior.  It didn't have anything to do with the OS that was
running.  Also, Solaris is System V, not BSD (/usr/ucb notwithstanding).

On OpenFirmware, sending a BREAK would drop the system to the firmware
prompt, which stopped the running OS (the firmware was essentially
always loaded and "running" in the background).  BIOS and U-Boot systems
don't operate like that (well, there are things like SMM, but that's
different).

-- 
Chris Adams <cma at cmadams.net>