我的 System 76 笔记本电脑运行 14.04 无法暂停。运行sudo pm-suspend失败，并显示以下内容/var/log/pm-suspend.log：
Running hook /usr/lib/pm-utils/sleep.d/94cpufreq suspend suspend:
/usr/lib/pm-utils/sleep.d/94cpufreq: 23: /usr/lib/pm-utils/sleep.d/94cpufreq: cannot create cpu0/cpufreq/scaling_governor: Read-only file system
...
/usr/lib/pm-utils/sleep.d/94cpufreq: 23: /usr/lib/pm-utils/sleep.d/94cpufreq: cannot create cpu7/cpufreq/scaling_governor: Read-only file system
/usr/lib/pm-utils/sleep.d/94cpufreq suspend suspend: Returned exit code 2.`
如果我禁用所有sleep.d尝试写入的脚本/sys，它仍然会失败：
/usr/sbin/pm-suspend: 321: /usr/sbin/pm-suspend: cannot create /sys/power/state: Read-only file system
sysfs 对我来说看起来非常正常：
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
# ls -al /sys/power
total 0
drwxr-xr-x 2 root root 0 Aug 14 10:25 .
dr-xr-xr-x 13 root root 0 Aug 14 09:47 ..
-rw-r--r-- 1 root root 4096 Aug 14 10:45 disk
-rw-r--r-- 1 root root 4096 Aug 14 11:05 image_size
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_async
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_freeze_timeout
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_print_times
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_test
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_trace
-rw-r--r-- 1 root root 4096 Aug 14 11:05 pm_trace_dev_match
-rw-r--r-- 1 root root 4096 Aug 14 11:05 reserved_size
-rw-r--r-- 1 root root 4096 Aug 14 11:05 resume
-rw-r--r-- 1 root root 4096 Aug 14 10:25 state
-rw-r--r-- 1 root root 4096 Aug 14 11:05 wakeup_count
尝试该命令时，我总是使用 sudo 或 su 来获取 root 权限。即使尝试手动使用内核的测试电源管理接口也会失败：
root@...:~# echo core > /sys/power/pm_test
-su: /sys/power/pm_test: Read-only file system
内核：3.13.0-33-generic #58-Ubuntu
所有软件包都是最新的。