The new G5 models have a new i2c keywest, the kernel dies when I boot with 'nosmp', 2.6.11 and 2.6.12rc4. i2c_keywest_init of_register_driver ... create_iface If booted without 'nosmp', smp_core99_cypress_tb_freeze() will panic because it gets -EIO from the first pmac_low_i2c_xfer() call.