diff --git a/arch/m68k/Kconfig.cpu b/arch/m68k/Kconfig.cpu
index b8884af365ae..3e70fb7a8d83 100644
--- a/arch/m68k/Kconfig.cpu
+++ b/arch/m68k/Kconfig.cpu
@@ -20,6 +20,7 @@ choice
 
 config M68KCLASSIC
 	bool "Classic M68K CPU family support"
+	select HAVE_ARCH_PFN_VALID
 
 config COLDFIRE
 	bool "Coldfire CPU family support"
@@ -377,11 +378,34 @@ config SINGLE_MEMORY_CHUNK
 	help
 	  Ignore all but the first contiguous chunk of physical memory for VM
 	  purposes.  This will save a few bytes kernel size and may speed up
-	  some operations.  Say N if not sure.
+	  some operations.
+	  When this option os set to N, you may want to lower "Maximum zone
+	  order" to save memory that could be wasted for unused memory map.
+	  Say N if not sure.
 
 config ARCH_DISCONTIGMEM_ENABLE
+	depends on BROKEN
 	def_bool MMU && !SINGLE_MEMORY_CHUNK
 
+config FORCE_MAX_ZONEORDER
+	int "Maximum zone order" if ADVANCED
+	depends on !SINGLE_MEMORY_CHUNK
+	default "11"
+	help
+	  The kernel memory allocator divides physically contiguous memory
+	  blocks into "zones", where each zone is a power of two number of
+	  pages.  This option selects the largest power of two that the kernel
+	  keeps in the memory allocator.  If you need to allocate very large
+	  blocks of physically contiguous memory, then you may need to
+	  increase this value.
+
+	  For systems that have holes in their physical address space this
+	  value also defines the minimal size of the hole that allows
+	  freeing unused memory map.
+
+	  This config option is actually maximum order plus one. For example,
+	  a value of 11 means that the largest free memory block is 2^10 pages.
+
 config 060_WRITETHROUGH
 	bool "Use write-through caching for 68060 supervisor accesses"
 	depends on ADVANCED && M68060