diff -r 34ab61cd89bb extras/mini-os/arch/x86/setup.c
--- a/extras/mini-os/arch/x86/setup.c	Tue Jan 30 21:26:45 2007 +0000
+++ b/extras/mini-os/arch/x86/setup.c	Tue Jan 30 21:45:46 2007 +0000
@@ -75,6 +75,13 @@ void
 void
 arch_init(start_info_t *si)
 {
+    if(VIRT_START & (L1_PAGETABLE_ENTRIES * PAGE_SIZE - 1))
+    {
+        printk("Virt address space has to start on 4Mb(2Mb for PAE) boundary. "
+               "\nPlease adjust start of the text section. Exiting\n");
+        do_exit();
+    }
+        
 	/* Copy the start_info struct to a globally-accessible area. */
 	/* WARN: don't do printk before here, it uses information from
 	   shared_info. Use xprintk instead. */