diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 05c6f6b..45454f3 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -100,6 +100,10 @@
  */
 #define LOWMEMSIZE()	(0x9f000)
 
+/* exceedingly early brk-like allocator */
+extern unsigned long _brk_end;
+void *extend_brk(size_t size, size_t align);
+
 #ifdef __i386__
 
 void __init i386_start_kernel(void);