powerpc/powernv: Ignore smt-enabled on Power8 and later

[Andy Whitcroft]

Hi Ubuntu kernel folks,

This patch isn't quite upstream stable material, but might still be nice to
have. It prevents smt-enabled=off on the kernel command line causing a hung
system at boot.

cheers

===

From: Greg Kurz <email address hidden>

Commit d70a54e2d08510a99b1f10eceeae6f2f7086e226 upstream.

Starting with POWER8, the subcore logic relies on all threads of a core
being booted so that they can participate in split mode switches. So on
those machines we ignore the smt_enabled_at_boot setting (smt-enabled on
the kernel command line).

Signed-off-by: Greg Kurz <email address hidden>
[mpe: Update comment and change log to be more precise]
Signed-off-by: Michael Ellerman <email address hidden>
---
 arch/powerpc/platforms/powernv/smp.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

[Leann Ogasawara (leannogasawara)]

This patch is currently in our 3.19 based unstable branch for Vivid. Marking this Fix Committed.

[Rolf Leggewie (r0lf)]

utopic has seen the end of its life and is no longer receiving any updates. Marking the utopic task for this ticket as "Won't Fix".

[Andy Whitcroft (apw)]

This bug was nominated against a series that is no longer supported, ie vivid. The bug task representing the vivid nomination is being closed as Won't Fix.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.