NAME
|
wd – hardware watchdog timer |
SYNOPSIS
|
bind –a #w /dev /dev/wdctl |
DESCRIPTION
|
This device presents textual information about hardware watchdog
timers on PCs and some other machines, and allows user–level control
of them. When enabled, a watchdog timer counts to zero in a few
seconds; upon reaching zero, it resets the machine with an NMI
or equivalent. Some process must periodically
restart the watchdog to avoid the NMI and keep the system alive;
watchdog(8) is one such program.
Reads from wdctl yield data of this form:
The watchdog is disabled at system shutdown, and when the last
open file descriptor for wdctl is closed. |
SOURCE
|
/sys/src/9/port/devwd.c /sys/src/9/*/*watchdog.c |
SEE ALSO
|
proc(3), watchdog(8) |
BUGS
|
On PCs, to ensure consistent use of one CPU's timers, an enable
message wires the issuing process (see proc(3)) to a CPU, and
any subsequent control messages will wire the issuing processes
to that same CPU. |