[gdb] Allow CPU architectures to omit support for GDB

Move the <gdbmach.h> file to <bits/gdbmach.h>, and provide a common
dummy implementation for all architectures that have not yet
implemented support for GDB.

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

src/include/bits/gdbmach.h

@@ -0,0 +1,45 @@
+#ifndef _BITS_GDBMACH_H
+#define _BITS_GDBMACH_H
+
+/** @file
+ *
+ * Dummy GDB architecture specifics
+ *
+ * This file is included only if the architecture does not provide its
+ * own version of this file.
+ *
+ */
+
+#include <stdint.h>
+
+typedef unsigned long gdbreg_t;
+
+/* Register snapshot */
+enum {
+	/* Not yet implemented */
+	GDBMACH_NREGS,
+};
+
+#define GDBMACH_SIZEOF_REGS ( GDBMACH_NREGS * sizeof ( gdbreg_t ) )
+
+static inline void gdbmach_set_pc ( gdbreg_t *regs, gdbreg_t pc ) {
+	/* Not yet implemented */
+	( void ) regs;
+	( void ) pc;
+}
+
+static inline void gdbmach_set_single_step ( gdbreg_t *regs, int step ) {
+	/* Not yet implemented */
+	( void ) regs;
+	( void ) step;
+}
+
+static inline void gdbmach_breakpoint ( void ) {
+	/* Not yet implemented */
+}
+
+extern int gdbmach_set_breakpoint ( int type, unsigned long addr, size_t len,
+				    int enable );
+extern void gdbmach_init ( void );
+
+#endif /* _BITS_GDBMACH_H */

src/include/ipxe/gdbstub.h

@@ -11,7 +11,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stdint.h>
 #include <ipxe/tables.h>
-#include <gdbmach.h>
+#include <bits/gdbmach.h>
 
 /**
  * A transport mechanism for the GDB protocol