[PATCH] ppc32: set smp_tb_synchronized on UP with SMP kernel

ppc32 kernel, when built with CONFIG_SMP and booted on a single CPU
machine, will not properly set smp_tb_synchronized, thus causing
gettimeofday() to not use the HW timebase and to be limited to jiffy
resolution.  This, among others, causes unacceptable pauses when launching
X.org.

Signed-Off-By: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/ppc/kernel/smp.c

@@ -301,6 +301,10 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 
 	/* Probe platform for CPUs: always linear. */
 	num_cpus = smp_ops->probe();
+
+	if (num_cpus < 2)
+		smp_tb_synchronized = 1;
+
 	for (i = 0; i < num_cpus; ++i)
 		cpu_set(i, cpu_possible_map);