[PATCH] ppc64: Fix UP kernel build

CONFIG_KEXEC breaks UP builds because of a misspelled smp_release_cpus().
Also, the function isn't defined unless built with CONFIG_SMP but it is
needed if we are to go from a UP to SMP kernel.  Enable it and document it.

Thanks to Steven Winiecki for reporting this and to Milton for remembering
how it's supposed to work and why.
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/head.S

@@ -2071,7 +2071,7 @@ _GLOBAL(hmt_start_secondary)
 	blr
 #endif
 
-#if defined(CONFIG_SMP) && !defined(CONFIG_PPC_ISERIES)
+#if defined(CONFIG_KEXEC) || (defined(CONFIG_SMP) && !defined(CONFIG_PPC_ISERIES))
 _GLOBAL(smp_release_cpus)
 	/* All secondary cpus are spinning on a common
 	 * spinloop, release them all now so they can start

arch/ppc64/kernel/machine_kexec.c

@@ -243,13 +243,17 @@ static void kexec_prepare_cpus(void)
 
 static void kexec_prepare_cpus(void)
 {
+	extern void smp_release_cpus(void);
 	/*
 	 * move the secondarys to us so that we can copy
 	 * the new kernel 0-0x100 safely
 	 *
 	 * do this if kexec in setup.c ?
+	 *
+	 * We need to release the cpus if we are ever going from an
+	 * UP to an SMP kernel.
 	 */
-	smp_relase_cpus();
+	smp_release_cpus();
 	if (ppc_md.cpu_irq_down)
 		ppc_md.cpu_irq_down();
 	local_irq_disable();