RE: PowerMac G5 crashes with "instruction storage interrupt" on recent 13

Armed with a lot of patience, I was able to bisect where the crashes are coming from. They seem to be due to these three consecutive and related commits (because the first one broke the build and required two extra fixes for powerpc’s GENERIC64 to build):

9171b8068b92 cpuset: Fix the KASAN and KMSAN builds
01f281d0ee52 Fix the build after 47a57144
971cb62e0b23 cpuset: Byte swap cpuset for compat32 on big endian architectures

Any idea on how to look into these crashes further?

Thank you!


From: Julio Merino<mailto:julio@meroh.net>
Sent: Sunday, July 31, 2022 07:45
To: freebsd-ppc@freebsd.org<mailto:freebsd-ppc@freebsd.org>
Subject: PowerMac G5 crashes with "instruction storage interrupt" on recent 13

Hi all,

I have a PowerMac G5 that’s running an old build of FreeBSD 13 stable (from around October of last year) that I’m trying to upgrade to recent stable/13.

Booting into a new kernel brings two issues: the first is that the fans spin up to jet engine levels right before transferring control to userspace. An old patch I have locally to mitigate this (which I got from whichever outstanding bug exists for this in the bug tracker) doesn’t seem to work any longer.

The second is that the kernel crashes (apparently) as soon as it tries to mount a ZFS pool during early stages of the boot process, but after successfully transferring control to userspace. Typing this from a photo of the crash so omitting details that I think aren’t going to be relevant here, like addresses, here is what I get:

----
Setting hostid: …
ZFS filesystem version: 5
ZFS storage pool version: features support (500)

Fatal kernel trap:

Exception = 0x400 (instruction storage interrupt)
…
pid = 64, comm = zpool

panic: instruction storage interrupt trap
cpuid = 1
time = …
KDB: stack backtrace:
#0 kdb_backtrace
#1 vpanic
#2 panic
#3 trap
#4 powerpc_interrupt
Uptime: 7s
----

Any thoughts about what I could look into? Any “recent” commits that you think may be at fault?

Thanks!