Hello Pádraig, On Wed, Aug 05, 2015 at 12:43:39AM +0100, Pádraig Brady wrote: > On 04/08/15 03:13, Guenter Roeck wrote: > > The watchdog infrastructure is currently purely passive, meaning > > it only passes information from user space to drivers and vice versa. > > > > Since watchdog hardware tends to have its own quirks, this can result > > in quite complex watchdog drivers. A number of scanarios are especially common. > > > > - A watchdog is always active and can not be disabled, or can not be disabled > > once enabled. To support such hardware, watchdog drivers have to implement > > their own timers and use those timers to trigger watchdog keepalives while > > the watchdog device is not or not yet opened. > > - A variant of this is the desire to enable a watchdog as soon as its driver > > has been instantiated, to protect the system while it is still booting up, > > but the watchdog daemon is not yet running. > > Just mentioning that patting the watchdog in the boot loader > (by patching grub etc.) can be a more general solution here as it > avoids hangs if the kernel crashes before it runs the watchdog driver, > which is especially true if PXE loaded across the net for example. > Also this tends to be better spaced between boot start and user space loading. the watchdog I'm currently working with on a powerpc platform has a unchangable timeout of ~1 s. To make the machine boot I patched the bootloader and need some automatic pinging in the kernel before userspace takes over. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
