At 8:48 AM -0500 12/14/04, Michael wrote:
>Stupid question - is this power saving stuff active for G4 CPUs? My iBook
>doesn't cool down when being idle, it only seems to heats up a little
>slower than under full load.

Not for your type of G4:

from cpu_subr.c

case MPC7457:
case MPC7455:
case MPC7450:
/* Enable the 7450 branch caches */
             hid0 |= HID0_SGE | HID0_BTIC;
             hid0 |= HID0_LRSTK | HID0_FOLD | HID0_BHT;
/* Disable BTIC on 7450 Rev 2.0 or earlier */
            if (vers == MPC7450 && (pvr & 0xFFFF) <= 0x0200)
                   hid0 &= ~HID0_BTIC;
/* Select NAP mode. */
           hid0 &= ~(HID0_DOZE | HID0_NAP | HID0_SLEEP);
           hid0 |= HID0_NAP | HID0_DPM;
           powersave = 0;/* but don't use it */
break;


So when Idle() in locore_subr.S gets to

#if defined(PPC_OEA)
/* Check if we can use power saving mode */
     lis%r8,_C_LABEL(powersave)@ha
     ldint%r9,_C_LABEL(powersave)@l(%r8)
     add.%r9,%r9,%r9
     ble1f

    sync
    mfmsr%r4
   oris%r4,%r4,PSL_POW@h/* enter power saving mode */
   mtmsr%r4
   isync

1:

you'll skip setting power saving mode.

tim