Pre-allocate guest address space

Allow pre-allocation of the guest virtual address space in usermode emulation.

Signed-off-by: Paul Brook <paul@codesourcery.com>
diff --git a/cpu-all.h b/cpu-all.h
index 47a5722..77eaf85 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -627,6 +627,7 @@
 #if defined(CONFIG_USE_GUEST_BASE)
 extern unsigned long guest_base;
 extern int have_guest_base;
+extern unsigned long reserved_va;
 #define GUEST_BASE guest_base
 #else
 #define GUEST_BASE 0ul