On Fri, Jul 11, 2008 at 1:59 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > On Friday, 11 of July 2008, Pavel Machek wrote: >> On Fri 2008-07-11 21:18:34, Rafael J. Wysocki wrote: >> > On Friday, 11 of July 2008, Pavel Machek wrote: >> > > On Wed 2008-07-09 21:37:18, Rafael J. Wysocki wrote: >> > > > On Tuesday, 8 of July 2008, Pavel Machek wrote: >> > > > > Hi! >> > > > > >> > > > > > According to the ACPI spec, ACPI NVS memory region is required to >> > > > > > be saved/restored by OS during hibernation. >> > > > > > >> > > > > > Section 15.3.2 ACPI Spec 3.0b, >> > > > > > "OSPM will call the _PTS control method some time before entering >> > > > > > a sleeping state, to allow the platform???s AML code to update >> > > > > > this memory image before entering the sleeping state. >> > > > > > After the system awakes from an S4 state, OSPM will restore this >> > > > > > memory area and call the _WAK control method to enable the BIOS >> > > > > > to reclaim its memory image." >> > > > > > >> > > > > > This patch set add the mechanism to save/restore ACPI NVS memory >> > > > > > during hibernation. >> > > > > > >> > > > > > Patch 01: call platform_begin before swsusp_shrink_memory. >> > > > > > So that we can allocate enough pages for ACPI NVS memory >> > > > > > before shrink the memory. >> > > > > >> > > > > Why is it neccessary to allocate memory for a copy? We should be able >> > > > > to save ACPI NVS area same way we are saving kernel pages, no? >> > > > >> > > > Because we want to restore it from the hibernated kernel (when it gets control >> > > > back again). >> > > >> > > Why is that important? So we can run some ACPI methods from hibernated >> > > kernel before restoring it? >> > >> > We're supposed to restore it right prior to executing _WAK, which is after >> > we've executed _BFS. This is a bit theoretical, because no one seems to >> > actaully implement _BFS, but well. >> >> Could we just call _BFS from the "loading" kernel, instead? That would >> save us that copying code... > > I'd prefer not to, because that would require the boot kernel to support ACPI, > which need not (and in fact should not IMO) be the case at present. > > Anyway, we'd have to either copy the NVS data into memory which is mapped and > can be saved, or to map the NVS area in order to save/restore it, which I > wouldn't like to do. io_remap doesn't work at that time? YH _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
