add lab4 spoc discuss

related_info/lab4/lab4-spoc-discuss/libs/error.h

@@ -0,0 +1,16 @@
+#ifndef __LIBS_ERROR_H__
+#define __LIBS_ERROR_H__
+
+/* kernel error codes -- keep in sync with list in lib/printfmt.c */
+#define E_UNSPECIFIED       1   // Unspecified or unknown problem
+#define E_BAD_PROC          2   // Process doesn't exist or otherwise
+#define E_INVAL             3   // Invalid parameter
+#define E_NO_MEM            4   // Request failed due to memory shortage
+#define E_NO_FREE_PROC      5   // Attempt to create a new process beyond
+#define E_FAULT             6   // Memory fault
+
+/* the maximum allowed */
+#define MAXERROR            6
+
+#endif /* !__LIBS_ERROR_H__ */
+