Re: A desktop environment[1] kernel wishlist

Olof Johansson
2015-04-30T17:23:59Z

Hi,

On Thu, Apr 30, 2015 at 10:10 AM, John Stultz <john.stultz@linaro.org> wrote:
> On Thu, Apr 30, 2015 at 9:25 AM, Bastien Nocera <hadess@hadess.net> wrote:
>> On Tue, 2014-10-21 at 10:04 -0700, John Stultz wrote:
>>> On Tue, Oct 21, 2014 at 1:49 AM, Bastien Nocera <hadess@hadess.net>
>>> wrote:
>>> > Hey,
>>> >
>>> > GNOME has had discussions with kernel developers in the past, and,
>>> > fortunately, in some cases we were able to make headway.
>>> >
>>> > There are however a number of items that we still don't have
>>> > solutions
>>> > for, items that kernel developers might not realise we'd like to
>>> > rely
>>> > on, or don't know that we'd make use of if merged.
>>> >
>>> > I've posted this list at:
>>> > https://wiki.gnome.org/BastienNocera/KernelWishlist
>>> >
>>> > Let me know on-list or off-list if you have any comments about
>>> > those, so
>>> > I can update the list.
>>>
>>> As for: 'Export of "wake reason" when the system wakes up (rtc alarm,
>>> lid open, etc.) and wakealarm (/sys/class/rtc/foo/wakealarm)
>>> documentation'
>>>
>>> Can you expand more on the rational for the need here? Is this for UI
>>> for power debugging, or something else?
>>
>> This is pretty much what I had in mind:
>> https://www.chromium.org/chromium-os/chromiumos-design-docs/lucid-sleep
>>
>> I guess I didn't make myself understood.
>
> My, admittedly quick skim, of that design document seems to suggest
> that lucid sleep would be a new kernel state. That would keep the
> kernel in charge of determining the state transitions (ie:
> SUSPEND-(alarm)->LUCID-(wakelock
> release)->SUSPEND-(alarm)->LUCID-(power-button)->AWAKE). Then it seems
> userspace would be able to query the current state. This avoids some
> of the races I was concerned with trying to detect which irq woke us
> from suspend from userspace.
>
> That said, the Power Manager section in that document sounds a little
> racy as it seems to rely on asking userspace if suspend is ok, rather
> then using userspace wakelocks, so I'm not sure how well baked this
> doc is.
>
> Olof: Can you comment on who's working on that design doc? Also the
> discussion around using freezing cgroups separately to distinguish
> between lucid and awake is interesting, but I wonder if we need to
> make wakeup_sources/wakelocks cgroup aware, or has that already been
> done?

Sameer and Chirantan have both been deeply involved in that project,
adding them on cc here.

-Olof