iPhone PM

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iPhone PM

Postby backendbilly » Mon Aug 31, 2015 11:07 pm

Hey J,

Your book says that iOs does not utilize ACPI for power management but never goes in detail on what it uses. My understanding is that I/O Kit takes care of the high level interface that queries the builtin PM. Is that builtin PM a kext loaded within the kernel or simply builtin the hardware?

Billy
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Re: iPhone PM

Postby morpheus » Fri Sep 18, 2015 8:53 am

A combination of both - they have a different system, with a user mode daemon (powerd) driving IOPowerManagement through a similar structure to OS X (IOPMRootDomain, etc). Just looking at it now for a second with jtool I was surprised that the disassembly produced automatically (on ARM64) is quite legible, including the MIG subsystem there, the necessary entitlements from clients, and the XPC stuff. AAPL left tons of symbols exposed and exported.. less work pour moi.

The reason it's not mentioned in the first volume is because I hadn't gotten to it by the time I hit my max page count with Wiley.. The 2nd ed will go (in its Volume II) to more detail. And powerd, like all the rest of the important daemons in iOS, will be subjected to full reversing probably for Volume I.

Sorry this took a while to answer. I'm lost in Shanghai at the moment.
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Re: iPhone PM

Postby backendbilly » Fri Sep 18, 2015 8:09 pm

Very happy to hear from you. I'm actually in Europe too for business and got lost a few times :lol: . I actually sent you a message nearly two weeks ago just checking up on you. Got me worried:). I hope you get back safe and sound.

Thanks for taking the time to investigate and reply.

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