Hi Wim and all, While investigating a customer case, it occurred to me that it is not always possible to figure out which driver is handling /dev/watchdog. For some drivers, /sys/dev/char/10:130 is a symbolic link to /sys/devices/virtual/misc/watchdog, and that virtual device says nothing about the physical device nor the device driver. As far as I can see, this happens whenever the dev.parent field of the watchdog_device structure isn't set before calling watchdog_register_device(). Couldn't we make setting this field mandatory, so that it is always possible to get to the physical device? It seems that only a minority of watchdog drivers are doing it properly at the moment. Also, it seems to me that at least in some cases, the parent device that is set isn't the right one. I am looking at the iTCO_wdt driver, it puts the PCI device as the parent, however the driver itself is a platform driver so it is attached to the iTCO_wdt platform device. That makes it impossible to find which driver is handling /dev/watchdog in an automated way: both /sys/dev/char/10:130 and /sys/class/watchdog/watchdog0 point to the PCI device, which has driver "lpc_ich" attached, not "iTCO_wdt". One has to enter the iTCO_wdt directory there to find the proper driver. May I suggest that dev.parent should point to the iTCO_wdt platform device in that case? If you need some background: my customer needs to unload the native watchdog driver and use the IPMI watchdog instead. So they need a reliable way to figure out who is handling /dev/watchdog so that they can unload the right module. This is rather difficult, costly and fragile with the way things are currently implemented. Thanks, -- Jean Delvare SUSE L3 Support -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
