You know how you see messages about writing to missing registers like these:
OS 9.2] Trying to write invalid spr 0 (0x000) at 00f113c0 11:26:23.910 WARNING [Mac OS 9.2] Trying to read invalid spr 0 (0x000) at 00f113c8 11:26:24.055 WARNING [Mac OS 9.2] Trying to write privileged spr 955 (0x3bb) at 00f164b8 11:26:24.055 WARNING [Mac OS 9.2] Trying to write invalid spr 959 (0x3bf) at 00f16520 11:26:24.055 WARNING [Mac OS 9.2] Trying to read invalid spr 959 (0x3bf) at 00f16528 11:26:24.056 WARNING [Mac OS 9.2] Trying to write invalid spr 944 (0x3b0) at 00f1653c 11:26:24.056 WARNING [Mac OS 9.2] Trying to read invalid spr 944 (0x3b0) at 00f16544 11:26:24.056 WARNING [Mac OS 9.2] Trying to write invalid spr 951 (0x3b7) at 00f16550 11:26:24.056 WARNING [Mac OS 9.2] Trying to read invalid spr 951 (0x3b7) at 00f16558 11:26:24.204 WARNING [Mac OS 9.2] Trying to write privileged spr 955 (0x3bb) at 00f164b8 11:26:24.204 WARNING [Mac OS 9.2] Trying to write invalid spr 959 (0x3bf) at 00f16520 11:26:24.204 WARNING [Mac OS 9.2] Trying to read invalid spr 959 (0x3bf) at 00f16528 11:26:24.204 WARNING [Mac OS 9.2] Trying to write invalid spr 944 (0x3b0) at 00f1653c 11:26:24.204 WARNING [Mac OS 9.2] Trying to read invalid spr 944 (0x3b0) at 00f16544 11:26:24.205 WARNING [Mac OS 9.2] Trying to write invalid spr 951 (0x3b7) at 00f16550 11:26:24.205 WARNING [Mac OS 9.2] Trying to read invalid spr 951 (0x3b7) at 00f16558
Should these registers be implemented? Maybe Apple expected these registers to be available on their hardware.
Using these files: http://www.nxp.com/files/32bit/doc/ref_manual/MPC7450UM.pdf page 1-36 and http://www.nxp.com/files/32bit/doc/data_sheet/MPC604.pdf page 19, as a guide, here is what I found out:
SPR Name
944 Monitor Control Register 2 951 Breakpoint Address Mask Register1 955 Sampled Instruction Address 1 959 Sampled Data Address * PowerPC 604 only
My current theory is there might be implementation details that are off in QEMU's emulated PowerPC 750 processor. The only way I know how to test this out is run QEMU in KVM mode on PowerPC hardware. I'm hoping someone out there has this setup available and can tell us if Mac OS 9.2 works better in KVM mode or not.