pmm changes

src/sys/mm/pmm.c

@@ -28,6 +28,7 @@ size_t* bitmap = 0;
 size_t usablememsize = 0;
 size_t totalmemsize  = 0;
 void* lastfree = PAGE_SIZE;
+void* pmm_usabletop;
 int lock = 0;
 
 static int getstate(void* addr){
@@ -236,4 +237,6 @@ void pmm_init(){
 
 	pmm_setused(bitmap, bitmappages);
 
+	pmm_usabletop = bitmaptop;
+
 }