add putch syscall for easier userspace debugging

+ Note that it is NOT intended for end user usage, just for debugging.

2 files changed, 32 insertions, 1 deletions

diff --git a/include/apos/syscalls.h b/include/apos/syscalls.h
index baa1139..84d9e07 100644
--- a/include/apos/syscalls.h
+++ b/include/apos/syscalls.h
@@ -12,10 +12,25 @@
 /** enum for now, possibly macros in the future once I get an approximate idea of
  * which syscalls are necessary etc. */
 enum {
-	/** @name Misc. */
+	/**
+	 * @name Misc.
+	 * Implementation in \ref dispatch.c instead of a separate file, as I
+	 * consider them 'internal' and not intended for users.
+	 */
 	/** @{ */
 	/** Noop, mainly for testing syscall subsystem and sanity checking. */
 	SYS_NOOP,
+
+	/**
+	 * Put a single character to the serial lines.
+	 * Do not rely on this actually working, as the serial drivers are only
+	 * included on debugging kernels.
+	 *
+	 * \todo Should serial drivers be always included and debugging mode
+	 * turned into whether \ref info is turned on or off or something?
+	 */
+	SYS_PUTCH,
+
 	/** @} */
 
 	/* @name Memory management. */
diff --git a/include/apos/uapi.h b/include/apos/uapi.h
index 6832f79..1ebdc21 100644
--- a/include/apos/uapi.h
+++ b/include/apos/uapi.h
@@ -181,6 +181,9 @@ struct sys_ret {
 	}                                                                      \
 	static inline struct sys_ret __##name
 
+/** @name Misc syscalls. */
+/** @{ */
+
 /**
  * Noop syscall.
  *
@@ -192,6 +195,19 @@ struct sys_ret {
  */
 SYSCALL_DECLARE0(noop);
 
+/**
+ * Putch syscall.
+ *
+ * @param ch Character to put.
+ * @param b Unused.
+ * @param c Unused.
+ * @param d Unused.
+ * @return \ref OK and 0.
+ */
+SYSCALL_DECLARE1(putch, ch);
+
+/** @} */
+
 /* @name Memory handling syscalls. */
 /** @{ */
 /**