kvm: BIOS E820 memory map emulation

This patch adds BIOS E820 memory map emulation to KVM.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

code16gcc.h

@@ -0,0 +1,15 @@
+/*
+ * code16gcc.h
+ *
+ * This file is -include'd when compiling 16-bit C code.
+ * Note: this asm() needs to be emitted before gcc emits any code.
+ * Depending on gcc version, this requires -fno-unit-at-a-time or
+ * -fno-toplevel-reorder.
+ *
+ * Hopefully gcc will eventually have a real -m16 option so we can
+ * drop this hack long term.
+ */
+
+#ifndef __ASSEMBLY__
+asm(".code16gcc");
+#endif