Messages in this thread | | | From | David Brownell <> | Subject | Re: Totally broken PCI PM calls | Date | Mon, 11 Oct 2004 14:37:17 -0700 |
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Hi Nigel,
On Monday 11 October 2004 2:17 pm, Nigel Cunningham wrote: > On Tue, 2004-10-12 at 02:36, David Brownell wrote: > > I've made that point too. STD is logically a few steps: quiesce system, > > write image to swap, change power state.
I'm hoping you agree with that abbreviated summary of what's involved! Pavel seemed to. Of course the devil is in the details, which I hope to leave mostly to others ... ;)
> > The ACPI spec talks about > > that as keeping the system in a G1/S4 powered state, but "swusp" > > doesn't use that ... it does a full power-off. And of course, > > full power-off > > means that the BIOS probably mucks with the USB hardware, so it's > > not a real resume any more. > > That's not necessarily true. Swsusp and suspend2 both include support > for enter ACPI S4 state. For suspend2 it's optional (to allow for broken > bioses). Not sure about whether it is with swsusp.
The machines I've tested with relatively generic 2.6.9-rc kernels don't use BIOS support for S4 when I call swsusp.
Of course the ACPI spec muddies the water by talking about two different states called "S4": "S4 Sleeping", which is what I was talking about as G1/S4; and "S4 Non-Volatile Sleep" that's more what I've seen with swusp: more like a G2 or G3 poweroff.
I'm willing to believe that there are systems on which swsusp tells drivers a less confusing story ... but I don't seem to have tested with those!
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