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Re: Setting power-on time on PowerMac

Hi Brad,

On Sun, 20 Sep 2020 19:14:21 -0700
Brad Boyer <flar@allandria.com> wrote:

> [...]
> This utility is abusing /dev/adb not to send an actual ADB message
> but instead to talk to the driver which owns ADB on the current
> system. The only mesage type all ADB drivers are required to handle
> is ADB_PACKET (which is message type 0x0). In fact, three of the
> five ADB drivers in the kernel only know about ADB_PACKET. The
> first byte of the write is the message type, and the rest is the
> message content. I suppose it's not abuse since the driver was
> specifically written to allow this, but it still seems a little
> non-intuitive to use this device for something that's not ADB.
> That program is sending a raw Cuda command (message type 0x1), so
> it will only work on systems that have Cuda whereas your PowerBook
> would have PMU instead.  The PMU driver emulates Cuda request 0x3
> (CUDA_GET_TIME) but doesn't emulate the more complex call being made
> to set the boot time (0xb which is CUDA_POWERUP_TIME). I don't see
> any indication the PMU is even capable of this functionality. My
> guess is that there isn't any way to make this work on your system.
> The hardware targeted by this program was only in desktop models,
> and not all desktop Macs have it either. That chip was introduced
> late in the m68k time frame and discontinued about the time Apple
> switched to AGP video cards. That iMac would be too new to still
> have Cuda and would instead also have PMU just like the PowerBook.

Thank you for the explanation.

This desktop has power-on timer functionality. I tested it set using OS X 10.4's pmset command.
I think there may be a PMU command for this that we don't know about. I might try to run Mac OS in qemu to see if I can trace its communication with the PMU to find it.


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