halting the kernel does not stop the CPU cores?

[Baruch Siach]

Hi Heinz,

On Thu, Jul 27, 2017 at 02:38:48PM +0000, Heinz Wrobel wrote:
> I noticed that when halting the kernel (intentionally or not), the cores 
> effectively go into a while(1) loop and power consumption on larger devices 
> really jumps up significantly to the point where, e.g., a “crash” turns into 
> “crash and burn”.
> 
> I would assume that if a system is halted, you don’t want to dissipate more 
> power than on a running system but go as silent as low power as reasonable.
> 
> Is there any specific reason why the cores would not go into a wfi loop like 
> they do on idle?
> The patch to fix this seems to be easy at first glance, but is there a good 
> reason *NOT* to do such a patch and to leave the plain while(1)?

See https://patchwork.kernel.org/patch/9866711/ .

baruch

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