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NullCPUPowerManagement explanation wanted

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Hi,

can someone tell me what exactly NullCPUPowerManagement is doing? I've read through many threads and most people tell you that you essentially disable AppleIntelCPUPowerManagement.

I can't believe that this is entirely true because of the following situation:

- My HP Elite 8200 worked without NullCPUPowerManagement in 10.8.4 and everything i supposed to work was working (Sleep, SpeedStep, ...). Hell, this machine didn't even needs a custom DSDT/SSDT to work perfect.
- With 10.8.5. the AppleIntelCPUPowerManagement produced a KP on boot, so i had to install NullCPUPowerManagement
- With NullCPUPowerManagement everything which worked before now also works (Sleep, SpeedStep, ...), it just tooks a little more time - without any exact measures imho around 2-3 seconds longer to go to sleep and wake up again.

So my guess is that NullCPUPowerManagement simply overrides some methods in AppleIntelCPUPowerManagement which cause the KP problem. I've tried to read through the sources of the Kext but unfortunately didn't exactly found out what it's doing (eventually do to my lack of knowledge of Apple specific API calls).

Can someone please shed some light into this?

Thanks,
egrath
 

RehabMan

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Hi,

can someone tell me what exactly NullCPUPowerManagement is doing? I've read through many threads and most people tell you that you essentially disable AppleIntelCPUPowerManagement.

Yes, that is what it does.

I can't believe that this is entirely true because of the following situation:

- My HP Elite 8200 worked without NullCPUPowerManagement in 10.8.4 and everything i supposed to work was working (Sleep, SpeedStep, ...). Hell, this machine didn't even needs a custom DSDT/SSDT to work perfect.

Maybe you had patched AppleIntelCPUPowerManagement installed.

- With 10.8.5. the AppleIntelCPUPowerManagement produced a KP on boot, so i had to install NullCPUPowerManagement

Or you could have used patched AppleIntelCPUPowerManagement.

- With NullCPUPowerManagement everything which worked before now also works (Sleep, SpeedStep, ...), it just tooks a little more time - without any exact measures imho around 2-3 seconds longer to go to sleep and wake up again.

Sleep and other power management functions usually do not work with NullCPU...

So my guess is that NullCPUPowerManagement simply overrides some methods in AppleIntelCPUPowerManagement which cause the KP problem. I've tried to read through the sources of the Kext but unfortunately didn't exactly found out what it's doing (eventually do to my lack of knowledge of Apple specific API calls).

It simply provides a replacement for AppleIntelCPUPowerManagement, keeping it from starting, but still setting up enough of the registry such that other IOKit drivers waiting for AppleIntelCPUPowerManagement to start will be "satisfied" with NullCPU.
 
Joined
Jan 18, 2013
Messages
61
Motherboard
HP Elite 8300 CMT
CPU
Intel i3-3770
Graphics
FirePro W7000
Mac
  1. MacBook
  2. Mac mini
Mobile Phone
  1. iOS
Hello RehabMan,

thanks for the clarification. I think i have to do a little more research in this case as the 10.8.4 installation i used was pretty vanilla (just FakeSMC and AppleIntelE1000) without a patched AppleIntelCPUPowerManagement.

I will keep this thread informed.

egrath
 
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