Anyone got a G4 Mini to test something for me?

[DearthnVader]

I need someone to test how to recover from a bad Open Firmware NVRAM value on a G4 Mac Mini.

No risk, just testing how to recover from a bad NVRAM value.

All you have to do is enter OF( Command+OPT+O+F at boot) set some non harmful value to something other than the default value like focde-debug? to true than shut-down and power up holding the power button, keep holding, hear the programers tone, keep holding, hear the boot chime, the system should enter OF with the defaults loaded.

So:

setenv fcode-debug? true
shut-down

Power the system holding the power button on the Mini until the system enters OF and:

printenv

 

[joevt]

I don't have a G4 mini. I have a Power Mac G5 Quad Core. Holding the power button for a long time did not give a programmers tone. It eventually gave a boot chime but it shuts down if the button is still held down. The nvram settings did not change.

Your G4 Mac mini isn't accepting Command-Option-P-R to reset the pram? It may require a USB 1.1 keyboard (not USB 2.0).

I have a Blue & White G3 but it's not setup currently.

 

[Wild Hare]

These help?

 

[joevt]

These help?

I think @DearthnVader wants to know if holding the power button until programmer's tone and boot chime is a method for setting those nvram variables to their defaults (the current values are on the left and the default values are on the right in your printenv output).

 

[DearthnVader]

These help?

View attachment 1882762View attachment 1882763

Yes I need to know if holding the power button loads OF with the defaults loaded.

@joevt I don't have a mini anymore to test with, I wanted to use the pci-probe-mask to mask the Airport Extreme card and the USB2 PCI device, they prevent sleep under OS 9, but I didn't want to give someone a bad value and leave them with an unbootable system.

On the iBook G4's that were Mac OS X only the PCI-probe-mask of 0xf8fbffff masks the two PCI devices and allows the system to enter sleep under OS 9, sadly we crash on sleep exit for some unknown reason maybe related to a hacked backlight driver.

So I wanted to see if the Mini could also sleep with a proper pci-probe-mask to see if it also crashes on sleep exit.

I just don't know anyway to debug a crash on sleep exit under OS 9, any clue Joe?

It would seem to me there would be a way, likely over a serial connection to debug it, but there just isn't any documentation I can find.

It would also seem that New World Macs that lack a true serial port should be able to setup a serial connection through the builtin modem port, if you poke around in Open Firmware you can see a serial device that resolves to the modem I just don't have any clue how to set it up to output OF to that serial device.

Surely Apple had a way to debug the OS 9 Nano Kernel on New World Macs, as the Nano Kernel log defaults to serial output.

 

[ervus]

Yes I need to know if holding the power button loads OF with the defaults loaded.

I put a 7448 into a mini but for OSX to run there is a powerlogix nvram script that tries to fix apple's shenanigans. Unfortunately this script bricks the mini and in order to recover I had to hold the power button to boot into OF where I could clear the script. The script is still there until I clear it in OF, so holding the button boots into OF but does not automatically clear the settings.

If you recall I also used this method to clear the DFS stuff that I tried for you.

 

[DearthnVader]

I put a 7448 into a mini but for OSX to run there is a powerlogix nvram script that tries to fix apple's shenanigans. Unfortunately this script bricks the mini and in order to recover I had to hold the power button to boot into OF where I could clear the script. The script is still there until I clear it in OF, so holding the button boots into OF but does not automatically clear the settings.

If you recall I also used this method to clear the DFS stuff that I tried for you.

Ok, that's what I needed to know, it does in fact boot with the defaults loaded. It does not clear nvram settings, that is as it should be, it just loads the defaults so you can clear the nvram via the command line in OF.

 

[joevt]

@joevt I don't have a mini anymore to test with, I wanted to use the pci-probe-mask to mask the Airport Extreme card and the USB2 PCI device, they prevent sleep under OS 9, but I didn't want to give someone a bad value and leave them with an unbootable system.

On the iBook G4's that were Mac OS X only the PCI-probe-mask of 0xf8fbffff masks the two PCI devices and allows the system to enter sleep under OS 9, sadly we crash on sleep exit for some unknown reason maybe related to a hacked backlight driver.

So I wanted to see if the Mini could also sleep with a proper pci-probe-mask to see if it also crashes on sleep exit.

Right. pci-probe-mask is going to be different for different Macs. I would get the ROM (or get the compiled fcode if the ROM is new and compressed or encrypted) and use my scripts/tools to disassemble/detokenize it then find the probe method and see what mask bits affect what devices are probed.

I just don't know anyway to debug a crash on sleep exit under OS 9, any clue Joe?

It would seem to me there would be a way, likely over a serial connection to debug it, but there just isn't any documentation I can find.

It's been ages since I touched OS 9. Debugging OS 9 for me usually involved Macsbug or Jasik's Debugger when not using Metrowerks debugger.
http://www.jasik.com/features.html
I don't remember ever doing two machine debugging in OS 9 which is probably something that would be required when dealing with sleep.

It would also seem that New World Macs that lack a true serial port should be able to setup a serial connection through the builtin modem port, if you poke around in Open Firmware you can see a serial device that resolves to the modem I just don't have any clue how to set it up to output OF to that serial device.

Surely Apple had a way to debug the OS 9 Nano Kernel on New World Macs, as the Nano Kernel log defaults to serial output.

I don't recall ever seeing a nano kernel log. For my B&W G3, there is a modem port to serial port adapter.
http://alexhixon.com/projects/jamport/index.html
http://www.oldschooldaw.com/forums/index.php?topic=380.0
https://apple.fandom.com/wiki/Griffin_gPort

You can use ttya:57600 (your serial port device might have a different name, maybe you have an scca alias?) as the input and output device to use 57600 bps. I think the default is 38400 bps. You can hack the ttya or scca init routine in Open Firmware so it uses 115200 or 230400 bps (change the init routine so that it will select the RTxC pin (3.8MHz) for the receive and transmit clocks instead of using the baud-rate generator then choose a x16 or x32 divider).

" ttya:57600" io