powerpc/configs: Bump kernel ring buffer size on 64 bit configs

When we issue a system reset, every CPU in the box prints an Oops,
including a backtrace. Each of these can be quite large (over 4kB)
and we may end up wrapping the ring buffer and losing important
information.

Bump the base size from 128kB to 256kB and the per CPU size from
4kB to 8kB.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/powernv_defconfig

@@ -15,6 +15,8 @@ CONFIG_TASK_XACCT=y
 CONFIG_TASK_IO_ACCOUNTING=y
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=18
+CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
 CONFIG_NUMA_BALANCING=y
 CONFIG_CGROUPS=y
 CONFIG_MEMCG=y

arch/powerpc/configs/ppc64_defconfig

@@ -10,6 +10,8 @@ CONFIG_TASKSTATS=y
 CONFIG_TASK_DELAY_ACCT=y
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=18
+CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
 CONFIG_CGROUPS=y
 CONFIG_CPUSETS=y
 CONFIG_BLK_DEV_INITRD=y

arch/powerpc/configs/pseries_defconfig

@@ -15,6 +15,8 @@ CONFIG_TASK_XACCT=y
 CONFIG_TASK_IO_ACCOUNTING=y
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=18
+CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
 CONFIG_NUMA_BALANCING=y
 CONFIG_NUMA_BALANCING_DEFAULT_ENABLED=y
 CONFIG_CGROUPS=y