Hi. On Sat, 2005-03-12 at 07:57, Patrick Mochel wrote: > On Fri, 11 Mar 2005, Nigel Cunningham wrote: > > > Hi. > > > > On Fri, 2005-03-11 at 16:28, David Zeuthen wrote: > > > Maybe I'm reading the source wrong, but isn't it the case that some > > > laptops using APM (my IBM thinkpad T41 with acpi=off for instance) > > > suspends without user space interaction when the lid is closed, thus > > > rendering it impossible to send the event from user space? > > > > > > One may even ask whether it's sound to assume that all architectures > > > will be suspended via user space? > > > > The most common way at the moment for a lid switch to activate > > suspending is via the userspace acpid daemon. I'd be mildly interested > > if you didn't have something equivalent running on your machine. > > APM doesn't work like that. There *might* be a way for the lid switch > interrupt to be passed to the kernel, which can the forward it to > userspace. But traditionally, the interrupt would generate an SMI and be > handled by the BIOS in a manner completely transparent to the OS (using > the Evil System Management Mode on x86 processor). Ah.. sorry. I missed those critical A P M letters :> Nigel > While it is true that APM is obsolete, a similar method to suspend some > systems may be employed by the system designer. I believe it's going to > be common in embedded systems, where an external signal triggers a suspend > transition. > > That doesn't preclude us from pushing the signal out to userpsace and > requiring userspace to trigger the susped through sysfs, but my general > opinion is that that solution is inelegant in principal and may not be > fast enough for people employing it. > > > Pat > 5B -- Nigel Cunningham Software Engineer, Canberra, Australia http://www.cyclades.com Bus: +61 (2) 6291 9554; Hme: +61 (2) 6292 8028; Mob: +61 (417) 100 574 Maintainer of Suspend2 Kernel Patches http://suspend2.net
