I'd like to know what is the best way to handle the watchdog timer in Linux? I've reviewed the docs and the watchdog framework and it's not really fitting my needs.
The system I'm upgrading turns on the WDT very early in the boot-loader There is code sprinkled through the boot-loader and then sprinkled through various init calls in Linux 2.4 that kick the WDT before it times out all through boot. Eventually when userspace comes up, a user program opens the WDT device and takes control of kicking it via an ioctl into a custom gpio driver. Of course there's still a few spots in the kernel and drivers that seem to kick the WDT during normal operation, so it's still a remote possibility that a reset wouldn't occur even if the user-space program died. As you might imagine, I don't like that the original coders simply, via trial and error, sprinkled a WDT kick call randomly through all the various kernel init calls in order to keep things going. I was hoping that with a formal WDT framework in 3.x that the kernel had some sort of hook to handle it in a clean and accepted manner. The kernel driver framework seems to assume that the WDT will only be handled by userspace and indeed doesn't start the WDT until the device is opened. As near as I can tell, there's no provision to handle a WDT that's started during or before kernel boot. True? It's important to note that the WDT on the MCF5235, once started, can not be disabled. And once it's time period is set, that can't be changed either. It's set at a max interval of about 8 seconds. I have thought of a few ways to proceed: 1. Implement a standard WDT that doesn't start till userspace opens the device and convince the system designers that's OK. 2. Implement the existing strategy and just sprinkle the kicking code through the kernel init and drivers, and add the standard WDT that userspace can open and take over with. 3. Implement some kernel process that takes over automatic periodic kicking until the real WDT driver is opened the first time by userspace. Then that process gets disabled. Anyway, any thoughts? How have other Coldfire projects handed the WDT in Linux? Thanks, - Steve _______________________________________________ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
