Date: Thu, 1 Feb 1996 00:57:18 -0700 (MST) From: Don Yuniskis <dgy@rtd.com> To: jkh@time.cdrom.com (Jordan K. Hubbard) Cc: freebsd-hackers@freefall.FreeBSD.org (FreeBSD hackers) Subject: Re: Watchdog timers (was: Re: Multi-Port Async Cards) Message-ID: <199602010757.AAA19863@seagull.rtd.com> In-Reply-To: <2257.823145561@time.cdrom.com> from "Jordan K. Hubbard" at Jan 31, 96 07:32:41 pm
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Greetings, People of Earth! > > I actually thought about this some time back, and have a suggestion > > for a ISA card: > > If you're going to go to all that trouble, why not simply add a > low-cost CPU and a serial port to it? Then you could also hook an > external modem to it and use it as a full-blown dial-in diagnostic > port for stopping the system in its tracks and sniffing around (or > poking at the corpse). I'd imagine the costs of laying out and > fabricating the boards would add such a "knee" in the cost curve that > another $100 in parts for several orders of magnitude's worth of extra > potential functionality would be a more than reasonable trade off. Does this gizmo *need* to reside within the "PC"? Are you really wanting to let it grab the bus, poke around, etc.? Or, would something more "passive" suffice (i.e. sitting on a serial port external to the PC)? I'm thinking of a box I designed which did pretty much the same thing (but for a different application). Essentially, a UART talking to the host and a UART talking to an external modem (or whatever). The MCU within would log messages coming in (from host) and could be programmed to autodial on a specific set of conditions. The intended application was remote data logging / error reporting. Could gather data or accounting information (again, that's what the particular application was concerned with) and report it to a remote facility periodically. Also had hooks for external events (like monitoring temperature, contact closures, etc.). I think this would "suffice" for crude watchdog with history... setup a syslog to /dev/ttyxxx so this gizmo logs all pertinent info (it had a boatload of NVRAM in it). And, tell it that if it doesn't get any data in "N" minutes, it should autodial and/or reboot the system (through an isolated contact closure). You could also configure it to try to login routinely (using a bogus uid that has '/usr/bin/who' or '/bin/ps -ax' as it's shell) so it can 1) verify that the system is up 2) see what's going on 3) autodial if it can't get a login prompt, etc. On the incoming side, it could be configured to autoanswer and allow a remote host to query the "log" it has recorded. Likewise, it could be directed to reset the attached host (i.e. close the isolated contacts). Does this fit the bill? I could see how much of this hardware and software I can contribute if it's along the right lines. Then, if someone wants to layout some boards and sell them for "cost", I'm sure *most* of you guys could figure out which end of a soldering iron to hold... :> --don
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