kernel: frameworks: Clarify requirements regarding file operations

Signed-off-by: Miquel Raynal <[email protected]>

slides/kernel-frameworks/kernel-frameworks.tex

@@ -132,12 +132,12 @@ \subsection{Character drivers}
   \begin{itemize}
   \item From the point of view of an application, a {\em character
       device} is essentially a {\bf file}.
-  \item The driver of a character device must therefore implement {\bf
-      operations} that let applications think the device is a file:
-    \code{open}, \code{close}, \code{read}, \code{write}, etc.
+  \item Character device drivers therefore implement {\bf operations}
+    that let applications think the device is a file.
   \item In order to achieve this, a character driver must implement
     the operations described in the \kstruct{file_operations}
-    structure and register them.
+    structure and register them: \code{open}, \code{read}, \code{write},
+    \code{ioctl}, etc.
   \item The Linux filesystem layer will ensure that the driver's
     operations are called when a user space application makes the
     corresponding system call.