1 files changed, 10 insertions, 1 deletions

diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/errno.h
index 1e1ea6e6e7a5..88e0914cf2d9 100644
--- a/include/uapi/asm-generic/errno.h
+++ b/include/uapi/asm-generic/errno.h
@@ -6,7 +6,16 @@
 #define EDEADLK         35      /* Resource deadlock would occur */
 #define ENAMETOOLONG    36      /* File name too long */
 #define ENOLCK          37      /* No record locks available */
-#define ENOSYS          38      /* Function not implemented */
+
+/*
+ * This error code is special: arch syscall entry code will return
+ * -ENOSYS if users try to call a syscall that doesn't exist.  To keep
+ * failures of syscalls that really do exist distinguishable from
+ * failures due to attempts to use a nonexistent syscall, syscall
+ * implementations should refrain from returning -ENOSYS.
+ */
+#define ENOSYS          38      /* Invalid system call number */
+
 #define ENOTEMPTY       39      /* Directory not empty */
 #define ELOOP           40      /* Too many symbolic links encountered */
 #define EWOULDBLOCK     EAGAIN  /* Operation would block */