Linux 下利用rtcwake唤醒设备

以下是在OpenSuse上所做的测试

whereis rtcwake

rtcwake: /usr/sbin/rtcwake /usr/share/man/man8/rtcwake.8.gz

rtcwake --help

Usage:

rtcwake [options]

Options:

-d, --device <device> select rtc device (rtc0|rtc1|...)

-n, --dry-run does everything, but suspend

-l, --local RTC uses local timezone

-m, --mode <mode> standby|mem|... sleep mode

-s, --seconds <seconds> seconds to sleep

-t, --time <time_t> time to wake

-u, --utc RTC uses UTC

-v, --verbose verbose messages

-h, --help display this help and exit

-V, --version output version information and exit

For more details see rtcwake(8).

standby

普通待机模式，为默认选项，对应ACPI state S1

mem

待机到内存，即内存之外把其他设备都进入低功耗模式，对应ACPI state S3

disk

待机到硬盘，即休眠，把电脑的当前状态保存到硬盘，几乎不消耗外部电源，对应ACPI state S4

off

通过调用系统的关机命令来休眠， 对应ACPI state S5

可以通过以下命令查阅当前系统支持的休眠模式

cat /sys/power/state

standby mem disk

我的电脑目前支持以上三种，但是测试发现休眠到disk的时候，机器会迅速醒来，standby和mem两种模式则工作正常，个中原因还不清楚。

执行该命令的时候需要root权限

1. 系统休眠后20seconds唤醒，加-v选项可以看到更多的打印信息

sudo rtcwake -v -s 20 -m mem 或

sudo rtcwake -v -s 20 -m standby

打印信息:

rtcwake -v -s 20 -m mem

Using UTC time.

delta = 0

tzone = 0

tzname = UTC

systime = 1393296617, (UTC) Tue Feb 25 02:50:17 2014

rtctime = 1393296617, (UTC) Tue Feb 25 02:50:17 2014

alarm 0, sys_time 1393296617, rtc_time 1393296617, seconds 20

rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Feb 25 02:50:38 2014

suspend mode: mem; suspending system

2. 系统在指定的时间醒来

rtcwake -v -t `date -d 10:53 +%s` -m mem

Using UTC time.

delta = 0

tzone = 0

tzname = UTC

systime = 1393296754, (UTC) Tue Feb 25 02:52:34 2014

rtctime = 1393296754, (UTC) Tue Feb 25 02:52:34 2014

alarm 1393296780, sys_time 1393296754, rtc_time 1393296754, seconds 0

rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Feb 25 02:53:00 2014

suspend mode: mem; suspending system

rtcwake -v -t `date -d 10:54 +%s` -m standby

Using UTC time.

delta = 0

tzone = 0

tzname = UTC

systime = 1393296794, (UTC) Tue Feb 25 02:53:14 2014

rtctime = 1393296794, (UTC) Tue Feb 25 02:53:14 2014

alarm 1393296840, sys_time 1393296794, rtc_time 1393296794, seconds 0

rtcwake: wakeup from "standby" using /dev/rtc0 at Tue Feb 25 02:54:00 2014

suspend mode: standby; suspending system

如果发现systime 和rtctime时间不一致，需要利用hwclock进行调整。