Re: suspend.c vs driver-model.txt

[Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>]

>Benjamin Herrenschmidt was arguing for doing driver_suspend() while
>userspace is still running. If you assumed stopped userspace, you
>don't have to add semaphore into device read() etc...

And stopping any kernel thread that may do that etc... I really
don't like it that much, but well, it can be a working solution for
2.6 for drivers having a direct userspace /dev interface.

>> > 2) we are running with just one active CPU.
>> 
>> Sure. We can tie that into subsystem notification, like this:
>> 
>> - The level at which we want to stop requests appears to be at the device 
>>   class level. 
>> 
>> - Device classes are coming RSN. 
>> 
>> - CPUs belong to a device class.
>> 
>> - We can integrate PM notication into device classes.
>> 
>> - The CPU device class can shut off all APs (application processors [silly 
>>   Intel term]).
>
>I believe shutting down CPUs should be done outside device_suspend()
>so all device_suspends() run on just one CPU...

That makes things easier, I tend to agree here.

Ben.




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