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Re: Kernel Ioctl

On Mon, 1 Apr 2002, Dan Erickson wrote:

> I asked the person I was talking to on #kernelnewbies what sends the 
> command? ie) the unsigned int cmd in ioctl.
> And he said a userspace program sends the command. Is this true?
> What I mean, is that something needs to say "I want to keep the computer 
> alive". So I will call WDIOC_KEEPALIVE to do this for me. And it was 
> highly confussing me as to what actualy sends the WDIOC_KEEPALIVE to the 
> driver.

Open the watchdog character device (e.g. /dev/watchdog) and then pass the 
file descriptor to ioctl(2), you can then manipulate the device 
using ioctl with the requested ioctl (e.g. WDIOC_KEEPALIVE) as the second 
paramter. So yes it is a userland program which you'd use. Try writing a 
watchdog program/daemon and you'll understand how it works.

Cheers,
	Zwane

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