10.5: Install 10.5 on an unsupported PowerPC iMac

Dec 22, '07 10:30:00AM

Contributed by: winddog

There are two parts to this solution; the first part covers installing Leopard on an unsupported 700mhz G4 iMac, and the second part fixes the sleep issues with the graphics drivers.

Part One: Installation using the DVD installation disk. The instructions below pretend that the iMac is an 867Mhz model. The change is temporary; after reboot the settings are lost.

  1. Insert installation DVD
  2. Reboot
  3. Hold down Command-Option-O-F to boot into open firmware
  4. At the prompt (>), type the following (note that the 0 below is a zero)
    dev /cpus/PowerPC,G4@0 
    d# 867000000 encode-int " clock-frequency" property 
    boot cd:,:tbxi 
  5. After the install disk has booted, you must load Terminal from the menu and enter the following:
    pmset -a displaysleep 0 halfdim 0 sleep 0 disksleep 0 force
    To verify your changes, type pmset -g. If this is not done, the install will freeze when the display or system tries to sleep during the install.
  6. After installation, go to the Energy Saver System Preferences panel, and set the machine to never sleep.
Read on for the sleep issue solution...

Fix the sleep issues by replacing the graphics drivers with the 10.4 drivers:

  1. Back up all of the GeForce* and NVDA* files in /System/Library/Extensions.
  2. Replace those drivers with the 10.4 files, ie. GeForce2MXGLDriver.bundle, GeForce.kext, etc. Note that there is not a one-to-one relationship with each file.
  3. Change ownership of the files as follows:
    bash$ sudo chown -Rh root:wheel GeForce* NVDA*
    bash$ sudo chmod -R a+rX,u+w,go-w GeForce* NVDA*
  4. Reboot
This should work with other unsupported models.

[robg adds: This should go without saying, but I'll say it anyway: changing things in open firmware can be dangerous. Installing OSes on unsupported systems and replacing drivers from previous releases can be dangerous. If you try this hint, Bad Things may happen to your hardware. Proceed at your own risk.]

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