On Sunday 27 May 2007, Matthew Garrett wrote:

f5f72b46c349fefcfd4421b2213c6ffb324c5e56 appears to break the userspace 
interface to the CMOS alarm. This could previously be accessed via 
/proc/acpi/alarm ...

I was a bit surprised the ACPI team didn't have more comments on
that issue, myself.  Thing is, all of /proc/acpi/* is deprecated
(scheduled for removal in barely over one month!) and nobody had
found any actual users of that "alarm" file when they searched for
them a while ago.  I suppose the conclusion then was that there
are no applications using it.

I'm not actually sure why this is the case. It doesn't look like the two 
interfaces are fundamentally incompatible.

ISTR the issue is that ACPI only allows one chunk of code to hook
into the relevant notifications.  So:  either /proc/acpi/wakeup;
or /sys/class/rtc/rtc0/wakealarm; but not both.

I agree that removing the  
proc code is a good long-term aim, but it'd be nice to be able to test 
the new RTC code without removing existing functionality.

Coexistence is unfortunately problematic here.  And with "long term"
documented to be a bit over a month ... I guess all I can say is
that if you can come up with a good patch to make both available,
please do so.

- Dave