diff -urN highmem-debug-ref/arch/i386/config.in highmem-debug/arch/i386/config.in
--- highmem-debug-ref/arch/i386/config.in	Tue Oct 23 12:56:05 2001
+++ highmem-debug/arch/i386/config.in	Tue Oct 23 12:57:17 2001
@@ -407,6 +407,9 @@
    bool '  Spinlock debugging' CONFIG_DEBUG_SPINLOCK
    bool '  Verbose BUG() reporting (adds 70K)' CONFIG_DEBUG_BUGVERBOSE
    bool '  Debug allocation faliures' CONFIG_DEBUG_GFP
+   if [ "$CONFIG_HIGHMEM" = "y" ]; then
+      bool '  Emulate HIGHMEM on lowmem machines' CONFIG_HIGHMEM_EMULATION
+   fi
 fi
 
 endmenu
diff -urN highmem-debug-ref/arch/i386/kernel/setup.c highmem-debug/arch/i386/kernel/setup.c
--- highmem-debug-ref/arch/i386/kernel/setup.c	Sun Oct 21 20:03:33 2001
+++ highmem-debug/arch/i386/kernel/setup.c	Tue Oct 23 12:57:35 2001
@@ -821,7 +821,20 @@
  */
 #define VMALLOC_RESERVE	(unsigned long)(128 << 20)
 #define MAXMEM		(unsigned long)(-PAGE_OFFSET-VMALLOC_RESERVE)
+#ifdef CONFIG_HIGHMEM_EMULATION
+#define ORDER_DOWN(x)	((x >> (MAX_ORDER-1)) << (MAX_ORDER-1))
+#define MAXMEM_PFN					\
+({							\
+	int __max_pfn;					\
+	if (max_pfn > PFN_DOWN(MAXMEM))			\
+	     __max_pfn = PFN_DOWN(MAXMEM);		\
+	else						\
+	     __max_pfn = ORDER_DOWN(max_pfn / 5);	\
+	__max_pfn;					\
+})
+#else
 #define MAXMEM_PFN	PFN_DOWN(MAXMEM)
+#endif
 #define MAX_NONPAE_PFN	(1 << 20)
 
 	/*