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- Last Reviewed: 10/05/2007
- WDT Watchdog Timer Interfaces For The Linux Operating System
- Alan Cox <alan@lxorguk.ukuu.org.uk>
- ICS WDT501-P
- ICS WDT501-P (no fan tachometer)
- ICS WDT500-P
- All the interfaces provide /dev/watchdog, which when open must be written
- to within a timeout or the machine will reboot. Each write delays the reboot
- time another timeout. In the case of the software watchdog the ability to
- reboot will depend on the state of the machines and interrupts. The hardware
- boards physically pull the machine down off their own onboard timers and
- will reboot from almost anything.
- A second temperature monitoring interface is available on the WDT501P cards.
- This provides /dev/temperature. This is the machine internal temperature in
- degrees Fahrenheit. Each read returns a single byte giving the temperature.
- The third interface logs kernel messages on additional alert events.
- The ICS ISA-bus wdt card cannot be safely probed for. Instead you need to
- pass IO address and IRQ boot parameters. E.g.:
- wdt.io=0x240 wdt.irq=11
- Other "wdt" driver parameters are:
- heartbeat Watchdog heartbeat in seconds (default 60)
- nowayout Watchdog cannot be stopped once started (kernel
- build parameter)
- tachometer WDT501-P Fan Tachometer support (0=disable, default=0)
- type WDT501-P Card type (500 or 501, default=500)
- Features
- --------
- WDT501P WDT500P
- Reboot Timer X X
- External Reboot X X
- I/O Port Monitor o o
- Temperature X o
- Fan Speed X o
- Power Under X o
- Power Over X o
- Overheat X o
- The external event interfaces on the WDT boards are not currently supported.
- Minor numbers are however allocated for it.
- Example Watchdog Driver: see samples/watchdog/watchdog-simple.c
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