When I upgraded my Ubuntu 14.04 to use kernel 4.0 (and now kernel 4.1) it apparently got a new feature: it would wake up from suspend in the middle of the day…

This bug provides a good read and has pointers to articles with more background. I’m seeing this on my Macbook Air and I am still not sure what the root cause is. I’m also not sure if it is “Intel Rapid Start Technology”, as Apples don’t have a BIOS to speak off.

What does seem to help is setting which thing (bus, controller, lid) can wakeup the computer. The file that controls this is /proc/acpi/wakeup (showing small snippet):

Device  S-state   Status   Sysfs node
XHC1      S3    *disabled  pci:0000:00:14.0
LID0      S4    *enabled   platform:PNP0C0D:00

Now, echo-ing LID0 to the file toggles that state, from enabled to disabled. For LID0 you probable want to keep it enabled. In my case I has to disable XHC1 for this to work - however I am still testing if this actually fixes things. Looking good though with the 4.1 kernel.

Update (28 June)⌗

Hmmm. I now see the opposite problem: laptop refused to suspend. A normal suspend looks like this:

% sudo acpi_listen
[sudo] password for miek:
button/lid LID close
button/lid LID open

But after a few cycles (or a long sleep?), acpi_listen does not see any events anymore…

Update (29 June)⌗

…And back to the kernel from Ubuntu 14.04 (3.13).