head -r365932 on PowerMac G5 (2 dual-core sockets): Crashes before login prompt if powerd is enabled in /etc/rc.conf

[Mark Millard]

This was discovered while doing a head -r363590 -> -r365932
upgrade to FreeBSD. (A non-debug system context.)

It first showed up only having updated the kernel. It still
shows up after updating world as well. It is now running:

# uname -apKU
FreeBSD FBSDG5L2 13.0-CURRENT FreeBSD 13.0-CURRENT #16 r365932M: Sun Sep 20 19:57:07 PDT 2020     root at FBSDFHUGE:/usr/obj/powerpc64vtsc_clang/powerpc.powerpc64/usr/src/powerpc.powerpc64/sys/GENERIC64vtsc-NODBG  powerpc powerpc64 1300115 1300115

but with /etc/rc.conf having powerd disabled:

#powerd_enable="YES"

The crash now is now silent, not getting to the db> prompt
and not showing any messages or backtrace.

Prior to world being updated it crashed with a traceback.
A quick summary from a camera picture:

fatal kernel trap:
. . .
pid = 1126, comm = powerd
. . .
kernel PGM trap by 0: . . .
at pcr_get+0x4c
at CPUFREQ_DRV_GET+0x78
at cpufreq_get_frequency+0x20
at cpufreq_get_level+0x2c
at cf_get_method+0x20c
at CPUFREQ_GET+0x78
at cpufreq_curr_sysctl+0x70
at sysctl_root_handler_locked+0x10c
at sysctl_root+0x26c
at userland_sysctl+0x14c
at sys___sysctl+0x8c
at syscallenter+0x188
at syscall+0x60
at trap+0x498
at powerpc_interrrupt+0x110
user SC trap . . .

After this I tried to make a dump and then proceeded
with disabling powerd in /etc/rc.conf and doing the
world update.

Unfortunately, while a dump was written, the core.txt
file from the -r365932 world boot that processed the
dump reported "invalid corefile" all over the place.

With powerpd disabled the G5 seems to be operational.
But turning powerd back on in /etc/rc.conf and rebooting
prevents the boot from completing, no messages, no
db> prompt. So I now leave powerd disabled.

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