[mp] Define an API for multiprocessor functions

Define an API for executing very limited functions on application
processors in a multiprocessor system, along with an x86-only
implementation.

The normal iPXE runtime environment is effectively non-existent on
application processors.  There is no ability to make firmware calls
(e.g. to write to a console), and there may be no stack space
available.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/arm/include/bits/mp.h

@@ -0,0 +1,12 @@
+#ifndef _BITS_MP_H
+#define _BITS_MP_H
+
+/** @file
+ *
+ * ARM-specific multiprocessor API implementation
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#endif /* _BITS_MP_H */