** Also affects: linux (Ubuntu Noble)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Oracular)
Importance: High
Status: Confirmed
** Changed in: linux (Ubuntu Noble)
Status: New => Confirmed
** Changed in: linux (Ubuntu Oracular)
Status: Confirmed => Fix Committed
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https://bugs.launchpad.net/bugs/2070329
Title:
KOP L2 guest fails to boot with 1 core - SMT8 topology
Status in The Ubuntu-power-systems project:
Confirmed
Status in linux package in Ubuntu:
Fix Committed
Status in linux source package in Noble:
Confirmed
Status in linux source package in Oracular:
Fix Committed
Bug description:
== Comment: #0 - SEETEENA THOUFEEK <sthou...@in.ibm.com> - 2024-06-25
01:24:11 ==
+++ This bug was initially created as a clone of Bug #205277 +++
---Problem Description---
KOP L2 guest fails to boot with 1 core - SMT8 topology
---Additional Hardware Info---
na
---Debugger Data---
na
---Steps to Reproduce---
KOP L2 guest fails to boot when we set the CPU topology as 1 core - SMT 8
command line used to verify the issue:
#!/bin/sh
QEMU="/home/mgautam/qemu"
qemu-system-ppc64 -s \
-drive file=/root/debian-12-nocloud-ppc64el.qcow2,format=qcow2 \
-m 20G \
-smp 8,cores=1,sockets=1,threads=8 \
-cpu host \
-nographic \
-machine pseries,ic-mode=xics -accel kvm \
-net nic,model=virtio \
-net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:10022-:22
NOTE: L2 boots fine when doorbells are turned off in L1 kernel
As per the investigation so far, the doorbell exception is not getting fired
inside L2 guest. At L1 level, if we set DPDES=1 in the GSB for L2, the guest
never receives the doorbell and also it is never cleared from the GSB. We are
discussing this behaviour with phyp team.
The root cause of this issue is lack of DPDES support at L1. I've
posted the fix upstream - https://lore.kernel.org/linuxppc-
dev/20240522084949.123148-1-gau...@linux.ibm.com/T/#u
The fix has been accepted upstream and will be backported for kernels >= 6.7
https://lore.kernel.org/linuxppc-dev/20240605113913.83715-1-gau...@linux.ibm.com/
---Patches Installed---
na
---System Hang---
na
---uname output---
na
Contact Information = na
Machine Type = na
Userspace rpm: na
Userspace tool common name: na
The userspace tool has the following bit modes: na
Userspace tool obtained from project website: na
*Additional Instructions for na:
-Post a private note with access information to the machine that is currently
in the debugger.
-Attach ltrace and strace of userspace application.
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