port-ofppc/58890: ofppc returning NULL for kernel pmap

[jack%zage.org.uk@localhost]

>Number:         58890
>Category:       port-ofppc
>Synopsis:       ofppc returning NULL for kernel pmap
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    port-ofppc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Dec 10 12:50:01 +0000 2024
>Originator:     Jack Dunn
>Release:        current
>Organization:
>Environment:
NetBSD bull 10.99.12 NetBSD 10.99.12 (ESCALA) #3: Tue Dec 10 11:01:11 GMT 2024  jack@eclipse:/home/jack/bull_build/sys/arch/ofppc/compile/ESCALA ofppc
>Description:
I have been working on getting NetBSD to run on my Bull Escala T604e which is an openfirmware based machine with PowerPC 604ev's. I started with 9.4 since that got further in the boot process. With that working I've moved on to 10.0/-current.

Running current with some Bull specific fixes I get the following pmap error:

[   1.0000000] Loaded initial symtab at 0x78f5ac, strtab at 0x7dca6c, # entries 19767
[   1.0000000] panic: pmap_pvo_find_va: returning NULL for kernel pmap, va: 0xa8000000

[   1.0000000] cpu0: Begin traceback...
[   1.0000000] 0x0082ad40: at vpanic+0x154
[   1.0000000] 0x0082ad70: at panic+0x50
[   1.0000000] 0x0082adb0: at pmap_pvo_find_va+0xffffa918
[   1.0000000] 0x0082adc0: at pmap32_extract+0xd8
[   1.0000000] 0x0082ade0: at uvm_km_check_empty+0x94
[   1.0000000] 0x0082ae20: at uvm_map+0xd8
[   1.0000000] 0x0082ae80: at uvm_km_suballoc+0x6c
[   1.0000000] 0x0082aea0: at uvm_pager_init+0x44
[   1.0000000] 0x0082aec0: at uvm_init+0x7c
[   1.0000000] 0x0082aee0: at main+0x54
[   1.0000000] 0x0082af10: at 0x1000e0
[   1.0000000] cpu0: End traceback...

I have narrowed this down to commit 1.121 of pmap.c (powerpc: oea: For OEA64_BRIDGE, 1:1 map up to 3GiB memory As done for OEA.).

A second issue with this commit is that it breaks video output on my machine which I haven't been able to narrow down. With the fixes applied below the machine will boot over serial console but will fault with a machine check exception in pmap_bootstrap2. Any thoughts on this would be appreciated.
>How-To-Repeat:
Build and run ofppc (I believe this will affect all ofppc machines)
>Fix:
ofppc seems to define it's own indexes for USER_SR, KERNEL_SR and KERNEL2_SR in ofppc/include/vmparam.h which appear to be incompatible with these changes.

Removing the definitions from ofppc/include/vmparam.h fixes my build (for serial console at least)