[mythtv-users] can't get wakealarm to write to BIOS

[Roger Siddons]

On Fri, 08 Dec 2017 19:53:14 +0100
"Marius Schrecker" <marius.schrecker at lyse.net> wrote:

> The board is an asus M3A78-CM and Power on From S5 By RTC Alarm is
> enabled

BIOS terminology is always rubbish but isn't that the "wake up at the time set by the BIOS screens" setting? 
If so, it should be *disabled* to allow linux to set an RTC wakeup time! IIRC the wiki mentions it somewhere...

For reference, I've got a 17.10 Dell desktop, on which I've never tried wakeup before:

BIOS has no HPET options and "Power-on from RTC" is Off

$ dmesg | grep rtc
[    1.727649] rtc_cmos 00:01: RTC can wake from S4
[    1.727774] rtc_cmos 00:01: rtc core: registered rtc_cmos as rtc0
[    1.727799] rtc_cmos 00:01: alarms up to one day, 242 bytes nvram,hpet irqs 
[    1.746656] rtc_cmos 00:01: setting system clock to 2017-12-09 08:42:36 UTC (1512808956)

$ dmesg | grep hpet
[    0.000000] clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 133484882848 ns 
[    0.000000] hpet clockevent registered 
[    0.477189] hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
[    0.477189] hpet0: 4 comparators, 64-bit 14.318180 MHz counter
[    0.478135] clocksource: Switched to clocksource hpet
[    1.727799] rtc_cmos 00:01: alarms up to one day, 242 bytes nvram,hpet irqs

$ sudo bash -c "echo `date '+%s' -d '+ 6 minutes'` > /sys/class/rtc/rtc0/wakealarm" $ cat /sys/class/rtc/rtc0/wakealarm
1512830274

$ date -d @1512830274
Sat  9 Dec 14:37:54 GMT 2017

$ cat /proc/driver/rtc
rtc_time	: 14:32:43
rtc_date	: 2017-12-09
alrm_time	: 14:37:54
alrm_date	: 2017-12-09
alarm_IRQ	: yes
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1024
max user IRQ frequency	: 64
24hr		: yes
periodic_IRQ	: no
update_IRQ	: no
HPET_emulated	: yes
BCD		: yes
DST_enable	: no
periodic_freq	: 1024
batt_status	: okay

$ sudo shutdown -h now

** It woke up at the right time **

$ cat /proc/driver/rtc
rtc_time	: 14:46:10
rtc_date	: 2017-12-09
alrm_time	: 14:37:54
alrm_date	: 2017-12-10
alarm_IRQ	: no
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1024
max user IRQ frequency	: 64
24hr		: yes
periodic_IRQ	: no
update_IRQ	: no
HPET_emulated	: yes
BCD		: yes
DST_enable	: no
periodic_freq	: 1024
batt_status	: okay