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Re: Off-Topic: G5 Open Firmware instability

On 13 May 2022, tonyj@suse.de wrote:
> Initially OF was stable but I noticed that the machine had stopped
> chiming at power on and in the course of trying the various fixes for
> this OF has become totally unstable.

The volume for the chime can be changed, also muted. I think it is an OF
NVRAM setting that does this, but I'm not sure if it's an obvious one or
e.g. a binary OF variable. There used to be an external (by an
independent developer) Mac OS X system settings panel that could be used
to set the "startup volume".

I downloaded ASD 2.6.3 which is the correct version for the hardware,
converted the dmg to iso. If I boot with 'c' the screen goes all grey
(which seems normal) then the machine hangs.  I can mount the ISO
from Linux using "-t hfsplus" and the contents seem correct.

My experience with .dmg's as images for boot media is that they are best
created under Mac OS X. I've had many corrupted CDs and I also had some
ATA/ATAPI optical drives that just wouldn't work, even with
known-working media. In any case the original Apple partition layout
matters, thus a converted ISO may not work.

In my experience it almost always worked to dd the raw contents of a
partition from an image/disc to a partition on the internal hard disk.
Setting the correct APM (Apple Partition Map) partition type is key
though, also make sure the partitions are the exact same size in blocks.
(I'd use mac-fdisk to accomplish this.) In my experience it is then
always bootable, and when holding the Option (Ctrl) key after turning on
the Power Mac (at the chime) it is listed as a valid boot option.
My point is: You could try to boot ASD from the internal hard disk...

> I've tried all of the usual fixes,  remove CMOS battery, power off
> for a day, clear NVRAM,  boot holding down power key to go thru
> programmers tone into OF.  This dinking is what made it worse :)

You did replace the PRAM battery, right? In my experience Power Macs act
up when a) no battery is installed and b) a weak/empty battery is used.
Anyway, if you didn't already, replace the battery with a new one. (And
make sure the new one isn't empty as well!)

Long story short, I also think that the liquid cooling needs checking
first, especially before trying anything like thermal calibration for
the CPUs/fans from ASD...

My Power Mac G5s are air cooled. The dual-CPU 2003 model also has one
hotter and one cooler CPU. I think that's normal. The dual-core
single-CPU 2005 model is also air cooled, and when the PRAM battery died
it would simply spin up the fans and hang with no OF and no boot.

I hope you can fix it. Good luck!
Linux User #330250

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