51 lines
1.8 KiB
Plaintext
Executable file
51 lines
1.8 KiB
Plaintext
Executable file
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
|