Re: [PATCH, RFC] [1/3] Generic in-kernel AC status

[Kyle Moffett <mrmacman_g4@mac.com>]

On Feb 12, 2006, at 05:17, Jan Engelhardt wrote:
>>>>> Ok. Maybe i am not seeing the point. But why do we need this in  
>>>>> the kernel?  Can't we handles this easily in userspace?
>>>>
>>>> Some kernel parts need to now: for example powernow-k8: some
>>>
>>> we can tell them from userspace.
>>
>> No, because battery will explode if you do not slow cpu down fast  
>> enough.
>
> How is that? APC UPS don't explode either if they are switching to  
> battery.

Yes, but APC UPS have big 3-inch fans blowing air over the batteries  
to keep them from overheating; laptops dont. Besides which, have you  
ever stuck your hand on a UPS while it's running a server on  
battery?  Those things get damn hot even with the fans, not even  
considering the fact that a lead-acid battery is much more efficient  
about storing and using energy than a Lithium-ion battery.

Incidentally, my UPS thermometer tells me that the peak load on- 
battery temp is more than 120 F; would you _really_ want that sitting  
on your lap in addition to all the heat generated by CPU, ram, GPU, etc?

There are real applications out there that have these problems, in  
fact a lot of manufacturers have issued recalls because of exploding  
batteries, power bricks, etc, indicating that this is not a simple  
problem.

Cheers,
Kyle Moffett

--
Diplomacy involves walking softly and _carrying_ a big stick.   
Actually using the big stick means the diplomacy part failed.
   -- Rob Landley