On Fri, Aug 25, 2006 at 01:39:25PM +0000, moreau francis wrote: > Russell King wrote: > > We have some folk who want a method to trigger emergency suspends when > > batteries got low, or if you move the battery cover, etc. These are > > events which require fast reactions from the system, and coding up some > > additional interface to pass such events to userland, have some daemon > > running to monitor for those events, and issue a PM event is completely > > overkill and, actually, unreliable. > > > > I'm not sure to understand why a daemon is needed. Could you explain ? Consider how you would make a connection between an interrupt being triggered and a suspend occuring, bearing in mind that you require a process context to perform a suspend. You essentially have three options: 1. a kernel thread, to which you pass an event or trigger condition. 2. a userland daemon which waits for the interrupt via some special kernel interface and triggers a suspend via normal userspace channels. 3. some hotplug-triggered userspace method. Note that both 2 and 3 have the same limitation - since they use normal userspace channels which have no concept of "emergency suspend", it's quite possible for (eg) a busy X server to inappropriately delay such a suspend. Therefore, I chose (1) as being the most appropriate solution. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core
