Created attachment 282743 [details]
kernel .config (PowerMac G4 MDD)
Trying out older kernels on the G4 MDD I noticed recent 4.9.x freeze the machine. Only message displayed in black letters on a white screen:
found display : /pco@f0000000/ATY,AlteracParent@10/ATY,Alterac_B@1, opening...
It's a hard freeze, RCU_CPU_STALL_TIMEOUT does not kick in.
Tried other stable kernels, which all worked:
So I suppose it's only a 4.9.x issue. Last working 4.9.x kernel I had in service was 4.9.161. First one I spotted freezing was 4.9.171. A bisect gave me the following commit:
1c38a84d45862be06ac418618981631eddbda741 is the first bad commit
Author: Michael Neuling <email@example.com>
Date: Thu Apr 11 21:45:59 2019 +1000
powerpc: Avoid code patching freed init sections
commit 51c3c62b58b357e8d35e4cc32f7b4ec907426fe3 upstream.
This stops us from doing code patching in init sections after they've
In this chain:
We have a code patching location at barrier_nospec() and
kvm_guest_init() is an init function. This whole chain gets inlined,
so when we free the init section (hence kvm_guest_init()), this code
goes away and hence should no longer be patched.
We seen this as userspace memory corruption when using a memory
checker while doing partition migration testing on powervm (this
starts the code patching post migration via
/sys/kernel/mobility/migration). In theory, it could also happen when
Cc: firstname.lastname@example.org # 4.13+
Signed-off-by: Michael Neuling <email@example.com>
Reviewed-by: Nicholas Piggin <firstname.lastname@example.org>
Reviewed-by: Christophe Leroy <email@example.com>
Signed-off-by: Michael Ellerman <firstname.lastname@example.org>
Signed-off-by: Sasha Levin <email@example.com>
Created attachment 282745 [details]
You are missing following commit:
(In reply to Christophe Leroy from comment #2)
> You are missing following commit:
Your fix landed in 4.9.177 and I can confirm my G4 boots fine now. Thanks!