Index: kernel/arch/amd64/include/mm/frame.h
===================================================================
--- kernel/arch/amd64/include/mm/frame.h	(revision 1c01e6cdfeee9466652e3b2b78ee532b3b041b26)
+++ kernel/arch/amd64/include/mm/frame.h	(revision 40c8c17482d672e755c855c6fd5664b0e933e483)
@@ -43,5 +43,4 @@
 #include <typedefs.h>
 
-extern uintptr_t last_frame;
 extern void frame_low_arch_init(void);
 extern void frame_high_arch_init(void);
Index: kernel/arch/amd64/src/mm/page.c
===================================================================
--- kernel/arch/amd64/src/mm/page.c	(revision 1c01e6cdfeee9466652e3b2b78ee532b3b041b26)
+++ kernel/arch/amd64/src/mm/page.c	(revision 40c8c17482d672e755c855c6fd5664b0e933e483)
@@ -64,7 +64,7 @@
 		
 	/*
-	 * PA2KA(identity) mapping for all frames.
+	 * PA2KA(identity) mapping for all low-memory frames.
 	 */
-	for (cur = 0; cur < min(config.identity_size, last_frame);
+	for (cur = 0; cur < min(config.identity_size, config.physmem_end);
 	    cur += FRAME_SIZE)
 		page_mapping_insert(AS_KERNEL, PA2KA(cur), cur, identity_flags);