diff --git a/user/diagdummy/block.h b/user/diagdummy/block.h
deleted file mode 100644
index cee21ca..0000000
--- a/user/diagdummy/block.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef DIAGDUMMY_BLOCK_H_
-#define DIAGDUMMY_BLOCK_H_
-
-void diagdummy_block(void);
-
-#endif // DIAGDUMMY_BLOCK_H_
diff --git a/user/diagdummy/diagdummy.c b/user/diagdummy/diagdummy.c
index 815a1f1..fd2399e 100644
--- a/user/diagdummy/diagdummy.c
+++ b/user/diagdummy/diagdummy.c
@@ -1,5 +1,7 @@
 #include <ulib.h>
-#include "block.h"
+
+#define CMDS(X)           \
+  X(block)      X(openf)
 
 void main(void) {
   if (argslen() == 0) {
@@ -9,9 +11,13 @@ void main(void) {
 
   char *cmd = args()[0];
 
-  if (string_strcmp(cmd, "block") == 0) {
-    diagdummy_block();
-  } else {
-    uprintf("diagdummy: unknown cmd %s\n", cmd);
+  #define X(name) if (string_strcmp(cmd, #name) == 0) { \
+    extern void diagdummy_ ## name(void); \
+    diagdummy_ ## name(); \
+    return; \
   }
+  CMDS(X)
+  #undef X
+
+  uprintf("diagdummy: unknown cmd %s\n", cmd);
 }
diff --git a/user/diagdummy/openf.c b/user/diagdummy/openf.c
new file mode 100644
index 0000000..27d57ad
--- /dev/null
+++ b/user/diagdummy/openf.c
@@ -0,0 +1,9 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <ulib.h>
+
+void diagdummy_openf(void) {
+  fsh_t h = fs_openf("base:/bin/init", FS_OF_READ);
+  uprintf("h = %d\n", h);
+  for(;;);
+}