I am only the messenger, so I cannot take credit for any of the below.
A clever developer has made a kernel-extension with the use of Intels own manual for the Core Duo processor. The code looks like the following (grabbed from
apple discussions)
#include <IOKit/IOLib.h>
int stop;
UInt8 data_org;
// Intel Manual on 945 Chipset, page 81, states that
// the offset for MMR space is at offset 44h of PCI Device 0 (Host Bridge)
// Here we read 0xfed14001
// It further states, page 186, that in MMR at offset 0xf10
// we can find a 32 bit value of which bits 1 and 0 control the Enhanced Power Management Mode of the Core Duo Processor:
// 00: All functions allowed
// 01: Disable C3 and C4
// 10: Disable C4
// The default value is 00
// This whole code is about setting this to 10
// Because after wake up from sleep it is set back to 00 we
// have a kernel thread which set to 10 every second
IOPhysicalAddress address = 0xfed14f10;
void qmb_control(){
UInt8 data;
data_org = IOMappedRead8(address);
data = data_org | 0x2;
stop = 0;
while (stop == 0)
{
IOMappedWrite8(address,data);
delay(1000000);
}
}
kern_return_t qmb_start (kmod_info_t * ki, void * d) {
IOCreateThread(qmb_control,NULL);
printf("KEXT has loaded!\n");
return KERN_SUCCESS;
}
kern_return_t qmb_stop (kmod_info_t * ki, void * d) {
// Before we can unload this Kernel Extension we have to signal qmb_control to exit.
// If we unload while qmb_control is still running the wake up timer of the loop
// will cause a kernel panic
stop = 1;
delay(2000000);
IOMappedWrite8(address,data_org);
printf("KEXT has unloaded!\n");
return KERN_SUCCESS;
}
What it does in practice is to turn off the Core Duo idle-mode every second (requires no or extremely little processor power) by moving a little bit in the setting. Unfortunately it has to do this every second because the system will wake (after system-sleep) with the bit set to idle-mode on.
Disabling the idle-mode will require the processor to use a little more power and thus remove the whine (in exactly the same way as using a bluetooth-mouse will remove the whine).
The down-side of this solution is added power-use (though the fall in battery-levels has been reported pretty low), also a higher processer-temp. is expected, nothing critical has been reported though.
Feel free to use this thread as a general feedback threat, so we will be able to learn more about the (easy) solution of just disabling the damn idle-mode all togetner.
A binary of the code can be downloaded
here - the code used to compile (and as stated above) is still a bit rough, and could have been made better - please refer to the apple discussions page above in order to see the details (scroll down to the bottom).
Note that nullriver software has compiled and is hosting the binary, the code was initially written by cbhense
It must be noted, that this of course is provided with no guaranties or responsibility from the auther etc. etc. (people can think by themselves, right?) - currently only tested on MacBook Pro - should work on MacBook (non-Pro) too - and should only be used with the current machines (future machines might use a different bit in setting the idle-mode and things could get messy - yadayadayada..)
Top