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Re: Curious why the PowerMac G5 quad needs a monitor to boot

On 5/8/19 13:30, John Paul Adrian Glaubitz wrote:
On 5/8/19 1:25 PM, Dennis Clarke wrote:
Sounds too much like work for an annoying little thing.
I will connect a KVM to it perhaps and that may solve it without
knowing why it happens.  As for a serial port or serial console,
in my dreams. There is no way that I know to attach a serial
port to these old things.

The older the hardware, the easier it usually is to hook up a serial
console. And it's usually a very good idea to use a serial console
as this is always the lowest common denominator.

Not for the 11,2 type G5s. AFAIK there never was an adapter available
that would allow access to the - existing - serial console port(s).
Though there was at least one such adapter available for the 7,3 type
G5s (which might also work in 7,2 type G5s). I know, because I have such
a device in my - at the moment again not working - 7,3 type G5. I think
it replaces the modem there, but the 11,2 type G5s don't have a modem so
perhaps the serial port pins are not accessible on the system board via
a connector there, preventing the creation of an easily attachable
adapter. If someone knows more, I'd love to hear from you, because a
serial console would really make that machine complete.


Apart from that, the behaviour Dennis described could be common to the
11,2 type G5s, as I seem to remember that mine also showed the same
behaviour some time ago. I wonder if this has something to do with the
kernel console. I've seen strange behaviour on other systems (i.e. a
rp2470) where it looked like the machine or kernel/system boot stalls as
long as the messages from the kernel console are not "consumed" in some
way. On the rp2470 the console is connected to a serial port of the GSP
and without a second console argument in the kernel command line, one
had to hit the enter key repetitively to allow the boot process to
complete. Not sure if that could also happen on a machine with glass
console only (i.e. the 11,2 type G5), but I could avoid that behaviour
on the rp2470 by adding a second console argument with a "bogus" console
device (e.g. `console=tty0`).


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