Hi Frederic,

On Fri, 8 Feb 2013 14:07:49 +1100 Stephen Rothwell [off-list ref] wrote:

quoted

This patch has the side effect of changing the default configurations:
(This is PowerPC pseries_defconfig before/after this patch)

@@ -119,8 +120,8 @@
 #
 # CPU/Task time and stats accounting
 #
-# CONFIG_TICK_CPU_ACCOUNTING is not set
-CONFIG_VIRT_CPU_ACCOUNTING=y
+CONFIG_TICK_CPU_ACCOUNTING=y
+# CONFIG_VIRT_CPU_ACCOUNTING_NATIVE is not set
 # CONFIG_BSD_PROCESS_ACCT is not set
 CONFIG_TASKSTATS=y
 CONFIG_TASK_DELAY_ACCT=y

I don't know if that was deliberate, but it was suprising.  I noticed
when this patch entered next-20130207.

I suspect that this is caused by the changes to init/Kconfig:

diff --git a/init/Kconfig b/init/Kconfig
index be8b7f5..a05f843 100644
--- a/init/Kconfig
+++ b/init/Kconfig

@@ -326,6 +326,9 @@ source "kernel/time/Kconfig"

 menu "CPU/Task time and stats accounting"

+config VIRT_CPU_ACCOUNTING
+       bool
+
 choice
        prompt "Cputime accounting"
        default TICK_CPU_ACCOUNTING if !PPC64

The next line of context is:

        default VIRT_CPU_ACCOUNTING if PPC64

Which may have needed changing as well?  Indeed, changing that to
VIRT_CPU_ACCOUNTING_NATIVE restores the old defaults.