On 11/05/2015 07:02 AM, David Gibson wrote:

On Wed, 4 Nov 2015 14:54:51 +0100
Laurent Vivier [off-list ref] wrote:

quoted

On 04/11/2015 13:34, Hari Bathini wrote:

quoted

On 10/16/2015 12:30 AM, Laurent Vivier wrote:

quoted

On kexec, all secondary offline CPUs are onlined before
starting the new kernel, this is not done in the case of kdump.

If kdump is configured and a kernel crash occurs whereas
some secondaries CPUs are offline (SMT=off),
the new kernel is not able to start them and displays some
"Processor X is stuck.".

Starting with POWER8, subcore logic relies on all threads of
core being booted. So, on startup kernel tries to start all
threads, and asks OPAL (or RTAS) to start all CPUs (including
threads). If a CPU has been offlined by the previous kernel,
it has not been returned to OPAL, and thus OPAL cannot restart
it: this CPU has been lost...

Signed-off-by: Laurent Vivier<redacted>

Hi Laurent,

Hi Hari,

quoted

Sorry for jumping too late into this.

better late than never :)

quoted

Are you seeing this issue even with the below patches:

pseries:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c1caae3de46a072d0855729aed6e793e536a4a55

Unfortunately, this is unlikely to be relevant - this fixes a failure
while setting up the kexec.  The problem we see occurs once we've
booted the second kernel and it's attempting to bring up secondary CPUs.

quoted

quoted

opal/powernv:
https://github.com/open-power/skiboot/commit/9ee56b5

Very interesting. Is there a way to have a firmware with the fix ?

 From Laurent's analysis of the crash, I don't think this will be

relevant either, but I'm not sure.  It would be very interesting to
know which (if any) released firmwares include this patch so we can
test it.

Hi Laurent/David,

I am not so sure on this. While I get back on this, can you confirm you are
seeing the issue in both PowerVM (pseries) and baremetal (powernv). What is
the kernel version where the issue is seen for PowerVM and/or baremetal.
Also, for baremetal, can you mention the OPAL version on which the issue is
reproducible. If a bug is raised for this, I would be happy to be 
pointed to,
to get more information on this.

Thanks
Hari

_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev