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Comment by janus | Hacker News Reader

Can someone explain what this patch actually does? I have an old Macbook Air with a malfunctioning sensor that cause the CPU to always run in powersaving mode (capped at 800 mhz), so it's basically unusable under OS X.

I have walked around this issue by installing Linux which allows me to tune the CPU governor manually, and it uncaps the artificial limit that the malfunctioning sensor puts.

Would this patch allow me to do something similar in Mountain Lion?

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You could try NullCPUPowerManagement.kext. It's used in the OS X x86 community to disable the built in Power management. If you don't mind getting your hands dirty you might be able to get it (or another related kext) to turn off frequency switching.

[1]http://www.osx86.net/downloads.php?do=file&id=16

I don't mind getting my hands dirty at all. I'll see if I can find any more info about this kext, thanks :)

The patch? No, but the technique can be used to make any change to the kernel, as long as you don't need more bytes.

The change you want likely is such a change, as, to me, it looks like a 'replace an if by a NOP or a jump always' patch.

You could also try this out... https://github.com/hholtmann/smcFanControl/tree/master/smc-c...

Will this also allow me to scale the cpu? I was already able to change the fan's speed .... thanks

The patch fixes a bug with how the SIGPROF signal is delivered to a process, ensuring that it gets delivered to the proper thread rather than an arbitrary thread. It's unrelated to anything in the area of powersaving or clock speed throttling.

great, thanks for pointing it out.

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