david@xxxxxxx wrote: > On Mon, 16 Jul 2007, Al Boldi wrote: > > We have to go through ACPI, for wakeup functions to succeed. A simple > > power-off won't do. > > the kexec switch being posted requires ACPI be disabled, so it's clearly > possible to switch kernels and initialize devices without ACPI It's a given that kexec works in the absence of ACPI; what we have to handle is the ACPI states across kernel invocations, to ensure wakeup functions succeed. If you don't need this, then just power off. > >> suspend-to-disk-and-ram could be implemented as three > >> seperate steps > >> > >> 1. suspend-to-disk > >> > >> 2. resume-from-disk > >> > >> 3. suspend-to-ram > >> > >> followed by either > >> > >> 4. resume-from-ram > >> > >> or > >> > >> 4. battery dies and loptop powers off completely > >> > >> 5. power-on boot. > >> > >> 6. resume-from-disk > >> > >> all that you need to do is to make sure that the system doesn't run > >> anything that would affect permanent media or the outside world between > >> steps #2 and #3 > > > > Exactly, which is why your scheme would break down on #3, and that's why > > you need to call S3 from within the kexec'd hibernation kernel after > > saving the hibernation image. > > when a kexec is called, how does the kernel know what to execute? > something needs to tell it what to do, and I think that something is > either something in the kexec image, or it's something passed as a > parameter to that image. > > all that would be needed to do #3 safely is to have the kernel that you > restarted on #2 do a suspend-to-ram before it does anything else. If you mean by kernel 'the normal kernel', then this won't work, because it would imply a change of state after saving its image. If you mean by kernel 'the kexec'd hibernation kernel', then you wouldn't need to do #2, but rather do #3 right after dumping the image in #1. [...insert from another post...] > > BTW, it would be really helpful if people would actually try the kexec > > hibernation patches, as this may yield a much more constructive > > discussion. > > I would love to, but so far I don't see the nessasary pieces > > once I kexec to the new kernel, how can it find out what pages of memory > (and swap) need to be saved? No need to save the swap, all you need to do is to dump /dev/oldmem onto storage, and if that dump image is compatible with swsusp, then a normal kernel should be able to resume from this image via /dev/snapshot. Thanks! -- Al _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
