diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 7474502dace5880cabc5046c49d5e3c7441481f9..cd870a823d18a89952d4b9d622bb080e3b5ffc5b 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -290,7 +290,8 @@ void __init setup_arch(char **cmdline_p)
 	conswitchp = &dummy_con;
 #endif
 
-	ppc_md.setup_arch();
+	if (ppc_md.setup_arch)
+		ppc_md.setup_arch();
 	if ( ppc_md.progress ) ppc_md.progress("arch: exit", 0x3eab);
 
 	paging_init();
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 3089eaed3256c7dda38f6922679cfeef57693019..008ab6823b022a1793259b62697008f15feb90d5 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -530,7 +530,8 @@ void __init setup_arch(char **cmdline_p)
 	conswitchp = &dummy_con;
 #endif
 
-	ppc_md.setup_arch();
+	if (ppc_md.setup_arch)
+		ppc_md.setup_arch();
 
 	paging_init();
 	ppc64_boot_msg(0x15, "Setup Done");
diff --git a/include/asm-powerpc/machdep.h b/include/asm-powerpc/machdep.h
index 71c6e7eb2a266798d56e3c6676d528fa1fa8be3f..cc7c17f16a9a71a2699d577ff644e63141ba5c32 100644
--- a/include/asm-powerpc/machdep.h
+++ b/include/asm-powerpc/machdep.h
@@ -99,7 +99,7 @@ struct machdep_calls {
 #endif /* CONFIG_PPC64 */
 
 	int		(*probe)(void);
-	void		(*setup_arch)(void);
+	void		(*setup_arch)(void); /* Optional, may be NULL */
 	void		(*init_early)(void);
 	/* Optional, may be NULL. */
 	void		(*show_cpuinfo)(struct seq_file *m);