On Mon, 7 May 2007, Rafael J. Wysocki wrote: > > G3 = "mechanical off" = no wakeup devices are enabled, > > safe to disassemble > > G2/S5 = "soft off" = wakeup may be enabled, not safe to > > disassemble > > S4 = "non-volatile sleep" = hibernation, memory image is saved > > S5 = "soft off" = almost the same as S4 except there is no > > memory image > > > > The spec does not explicitly associate S4 with either G2 or G3, and in > > fact it contains language suggesting very strongly that the system could > > be in either one. The spec also uses the same name for G2 and for S5, no > > doubt leading to extra levels of confusion. > > Well, it's quite clearly stated in 4.5 and in 15 that S4 belongs to G1. > Moreover, it's reiterated several times in different places that > S5 Soft off = G2. More confusion in the spec... It describes two different kinds of S4 states! I was talking about "S4 Non-Volatile Sleep", defined on p.20 just above Table 2-1. The text says this: The machine will then enter the S4 state. When the system leaves the Soft Off or Mechanical Off state,... That's a pretty clear indication that S4-NVS involves G2 or G3. You're talking about "S4 Sleeping State", defined on p.22, section 2.4. Evidently these two "S4" states are quite different. > The problem is that ACPI insists on treating S4 as a sleeping state. Section 2.4 is rather confusing. What I gather is that S4 and S5 are essentially the same except for the presence or absence of a stored memory snapshot. And yet S4 counts as a sleeping state while S5 doesn't. What's the explanation for that? > Still, I agree that what we do in steps 1 - 5 should be independent of > whether or not we're going to enter S4. Devices should not be > suspended before creating the image, because the system is not going to > enter any power state *at that time*. There seems to be no reason whatsoever > for putting devices in low power states for creating the hibernation image. Agreed. > There's nothing like G2/S4 in ACPI and we shouldn't refer to such a notion to > avoid confusion. Except for the text on p.20. > That's why I said that what we want to call 'hibernation' is and will probably > always be different from an ACPI transition to S4 (at least until we make a > bootloader capable of reading suspend images and ACPI-aware). In what sense is the boot kernel different from a "bootloader"? It certainly is capable of reading suspend images and is ACPI-aware. Alan Stern _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
