Date: Thu, 16 Oct 2025 09:56:55 -0700 From: Mark Millard <marklmi@yahoo.com> To: obiwac <obiwac@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Cc: Warner Losh <imp@bsdimp.com> Subject: Re: S4 hibernate design document [corrections] Message-ID: <76B06FB8-67A1-41B9-99E4-4CE79EB6C9B0@yahoo.com> In-Reply-To: <9E014B66-CE52-45D1-9DA3-3AEF3726CB1C@yahoo.com>
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[Fixing missing text and some odd copy/paste results.] On Oct 16, 2025, at 09:29, Mark Millard <marklmi@yahoo.com> wrote: > obiwac <obiwac_at_freebsd.org> wrote on > Date: Thu, 16 Oct 2025 14:19:43 UTC : > >> Hi again! >> >> Following up on the previous email announcing the Foundation's intent to add S4 >> hibernate support to FreeBSD [1], kib@ has started working on a more detailed >> design document for this: >> >> https://hackmd.io/@eJNIw-SNShyq1LSp2azAcw/Bka-kXTpge >> >> There are still a couple unsolved bits of the design, so we'd like to gather >> some more feedback on this document. If you could reply with any feedback >> within a week (before Oct 23rd) that would be ideal for us! >> >> Thanks, >> Aymeric on behalf of the FreeBSD Foundation >> >> [1] https://lists.freebsd.org/archives/freebsd-current/2025-August/008616.html > > I'm not sure how it fits with the material referenced above, but I'll > note that ACPI references S4 handling in at least the following, > including some of the _OSC usage that is tied to USB4 handling . . . > > > 6.2.11. _OSC (Operating System Capabilities) > > . . . > > Since platform context is lost when the platform enters the S4 sleeping state, OSPM > must re-evaluate _OSC upon wake from S4 to restore the previous platform state. > This requirement will vary depending on the device specific _OSC functionality. [I had originally noticed that what should have been "platform" was odd by being 'pla"orm' but managed to not type the "f" in the "tf" correction text each time.] [The "ti" in "functionality" had been a "!".] > . . . > > 6.2.11.1.2. Evaluation Conditions I should have quoted here: QUOTE The OS must evaluate _OSC under the following conditions: END QUOTE > . . . > > Upon resume from S4. Platform firmware will handle context restoration when > resuming from S1-S3. [I had originally noticed that what should have been "platform" was odd by being 'pla"orm' but managed to not type the "f" in the "tf" correction text each time.] [The "ti" in "restoration" had been a "!".] > > . . . > > 6.2.11.3. Operating System Capabilities (_OSC) for USB > > . . . > > Note: OSPM must re-invoke _OSC during S4 resume. > > . . . > > 6.3. Device Insertion, Removal, and Status Objects > > . . . > > For removing devices, ACPI supports both hot removal (system is in the S0 state), > and warm removal (system is in a sleep state: S1-S4). This is done using the _EJx > control methods. Devices that can be ejected include an _EJx control method for > each sleeping state the device supports (a maximum of 2 _EJx objects can be listed). > For example, hot removal devices would supply an _EJ0; warm removal devices > would use one of _EJ1-EJ4. These control methods are used to signal the hardware > when an eject is to occur. > > The sequence of events for dynamically removing a device goes as follows: > > . . . > === Mark Millard marklmi at yahoo.comhome | help
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