睡眠时如何在OSX上安装USB设备？

Question

通常在计算机醒着时会挂载USB设备。我正在编写程序以通过USB设备唤醒计算机，但是计算机在睡眠时无法识别USB设备。如何解决此问题？

Answer 1

you can not mount a device while sleeping because the sleep state is a either SUSPEND_TO_MEMORY or SUSPEND_TO_DISK in that not all functions of the machine are available ( https://en.wikipedia.org/wiki/Sleep_mode )

you can wakeup the machine over USB ( wake up event ). the principle of USB wakeup is similar to WOL ( https://en.wikipedia.org/wiki/Wake-on-LAN ). a special interupt is send to the host what triggers the host to wake up. not all USB devices are able to generate this interrupt, mass storage devices like USB sticks are not able, mice and keyboards and ... are ( https://msdn.microsoft.com/en-us/library/windows/hardware/ff537628(v=vs.85).aspx , https://msdn.microsoft.com/en-us/library/windows/hardware/ff551766(v=vs.85).aspx ). maybe it is possible to emulate this interrupt with a USB mass storage device however then you have to modify the firmware of the device and this close to impossible if you do not develop your own mass storage device

in http://bernaerts.dyndns.org/linux/74-ubuntu/220-ubuntu-resume-usb-hid is example for linux