Re: Booting and Installing Release 12 on PowerMac G5 "Quad Core"

[ For head usefdt=1 does work by itself without reverting VM_MAX_KERNEL_ADDRESS .]

On 2019-Jan-27, at 21:57, Mark Millard <[email protected]> wrote:



> On 2019-Jan-27, at 16:05, Curtis Hamilton <clhamilto at gmail.com> wrote:
> 
>> Is there a recommended solution to booting/installing Release 12 on the PowerMac G5 "Quad Core"?
>> 
>> I've read through all the threads in this mailing list, but have yet to find a solution that works on my Mac.  Many of the referenced snapshot kernels could not be located.  Building from source yielded the same results as down loaded pre-built images.
>> 
>> Any tips or hits would be appreciated.
> 
> A specific change was made for powerpc64 that lead to this G5 boot problem.
> However, it appears to just have exposed some previously unknown problem rather
> than the change itself being wrong. I'm not aware of anyone having figured
> out the underlying problem --or even of having figured out a way to figure
> it out. I know I've not come up with any ideas so far. So far as I know, only
> old PowerMacs show such odd behavior with the change.
> 
> So for now I base my builds on reverting the change in question. (I normally
> use head, including 12 back when it was head.)
> 
> . . ./sys/powerpc/include/vmparam.h has a definition of VM_MAX_KERNEL_ADDRESS .
> I reverted the:
> 
> #define VM_MAX_KERNEL_ADDRESS           0xe0000007ffffffffUL
> 
> to be:
> 
> #define VM_MAX_KERNEL_ADDRESS           0xe0000001c7ffffffUL
> 
> instead. But, again, I expect that this is a way of sidestepping another
> problem that has not been found: a hack/workaround instead of a valid,
> general fix.
> 
> Disabling smp via the following at the loader prompt seems to avoid
> the problem without such a change to to VM_MAX_KERNEL_ADDRESS :
> 
> set kern.smp.disabled=1
> 
> Nothing else has to be set to my knowledge. But using a single CPU/core
> has other consequences that may be of note depending on what one wants
> to do with the G5.
> 
> 
> 
> [For the following: I believe it only applies to head , not even
> stable/12: The fix so that usefdt would work at all ( -r341614 )
> is for . . ./sys/powerpc/powermac/macgpio.c and has not been
> merged to stable/12 ( and, so, not to release/12.0.0 ).]
> 
> As far as I know the following by itself at the loader prompt does not
> side step the VM_MAX_KERNEL_ADDRESS related problem:
> 
> set usefdt=1

I realized that I'd not tried usefdt=1 by itself after it was fixed.
So I built and installed a kernel without reverting VM_MAX_KERNEL_ADDRESS
and tried it using "set usefdt=1" and it worked just fine. (It did swap
the 0 vs. 1 of the ethernet ports.)

So I'll probably modify my loader to be a variant that does not
require the explicit set usefdt=1 for powermacs and see how that goes.

> 
> However, usefdt should avoid other issues with mixing use of Apple's
> OpenFirmware with FreeBSD execution. (It does swap which Ethernet
> port is 0 vs. 1 as seen in FreeBSD.)
> 
> So once stable/12 has the update to sys/powerpc/powermac/macgpio.c
> then usefdt=1 would likely be recommended for stable/12 as well.
> (It will be a while before it shows up in a release/12.?.? .)





===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)

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