[mythtv-users] want to disable /proc/acpi/alarm wakeup

Craig Huff huffcs at yahoo.com
Wed Jun 27 13:29:55 UTC 2007


Mark,

I struggled to get it to work and then couldn't figure out how to stop it either (but only for awhile ;-]).

What I had to do was modify the shell script /etc/init.d/halt (at least that's what I think it was).
Search for "/etc/proc/acpi".  What I did was add code to test if the time was 00:00:00 since I should
**never** be waking up **exactly** on the hour because I specify a lead time to allow the system to
come up and I further (in my paranoia) start recordings before the show is supposed to start since
I've seen stations that haven't joined the 20th century yet and can't tell what time it is.

All this to say that if the alarm time is 00:00:00, then I am sure I didn't set it to wake up and do 
something, so I take that as a flag *not* to wake up.  So, when I find that value, I don't do the 
normal processing.  Without the code in front of me, I can't be more specific, but IIRC, there was 
a sequencing issue where the alarm time had to be written to HW  **after**  the clock time is 
written to HW before shutdown in order for the alarm to happen.

When I fixed it so the alarm could wake up the system, I then had to add more code to *not* wake
up when the time was 00:00:00.

As I wrote this, it occurred to me that I could just as easily have used an invalid time value as the 
flag, such as 99:99:99, but it hadn't occurred to me before and I suspect there are/were other things 
that might set the alarm time that intend to disable the alarm by "clearing" it to 00:00:00.

On my mobo, the BIOS alarm disable control only affected the APM alarm, **not** the ACPI alarm.



If this explanation leaves things still as clear as mud, let me know and I'll try to post my modified 

version of /etc/init.d/halt (or whatever the correct file is ;-]).


Craig.



 
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