Documented all the sysdeps (only briefly, I admit).

Except for Filters, RIP and OSPF, the progdocs are complete.

sysdep/Doc

@@ -1 +1,2 @@
+D sysdep.sgml
 C unix

sysdep/sysdep.sgml

@@ -0,0 +1,27 @@
+<!--
+	BIRD Programmer's Guide: Sysdeps
+
+	(c) 2000 Martin Mares <mj@ucw.cz>
+-->
+
+<chapt>System dependent parts
+
+<sect>Introduction
+
+<p>We've tried to make BIRD as portable as possible, but unfortunately
+communication with the network stack differs from one OS to another,
+so we need at least some OS specific code. The good news is that this
+code is isolated in a small set of modules:
+
+<descrip>
+<tagp><tt/config.h/</tagp> is a header file with configuration information,
+definition of the standard set of types and so on.
+<tagp/Startup module/ controls BIRD startup. Common for a family of OS'es (e.g.,
+for all Unices).
+<tagp/Logging module/ manages the system logs. [per OS family]
+<tagp/IO module/ gives an implementation of sockets, timers and the
+global event queue. [per OS family]
+<tagp/KRT module/ implements the Kernel and Device protocols. This
+is the most arcane part of the system dependent stuff and some
+functions differ even between various releases of a single OS.
+</descrip>

sysdep/unix/Doc

@@ -1,4 +1,3 @@
-H UNIX system dependent parts
 S log.c
 S krt.c
 # io.c is documented under Resources

sysdep/unix/krt.c

@@ -6,6 +6,39 @@
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
+/**
+ * DOC: Kernel synchronization
+ *
+ * This system dependent module implements the Kernel and Device protocol,
+ * that is synchronization of interface lists and routing tables with the
+ * OS kernel.
+ *
+ * The whole kernel synchronization is a bit messy and touches some internals
+ * of the routing table engine, because routing table maintenance is a typical
+ * example of the proverbial compatibility between different Unices and we want
+ * to keep the overhead of our krt business as low as possible and avoid maintaining
+ * a local routing table copy.
+ *
+ * The kernel syncer can work in three different modes (according to system config header):
+ * Either with a single routing table and single KRT protocol [traditional Unix]
+ * or with many routing tables and separate krt protocols for all of them
+ * or with many routing tables, but every scan including all tables, so we start
+ * separate krt protocols which cooperate with each other  [Linux 2.2].
+ * In this case, we keep only a single scan timer.
+ *
+ * We use FIB node flags to keep track of route synchronization status. We also
+ * attach temporary &rte's to the routing tables, but it cannot harm the rest of
+ * BIRD since table synchronization is an atomic process.
+ *
+ * When starting up, we cheat by looking if there is another
+ * KRT instance to be initialized later and performing table scan
+ * only once for all the instances.
+ */
+
+/*
+ *  If you are brave enough, continue now.  You cannot say you haven't been warned.
+ */
+
 #undef LOCAL_DEBUG
 
 #include "nest/bird.h"
@@ -18,30 +51,6 @@
 #include "unix.h"
 #include "krt.h"
 
-/*
- *  The whole kernel synchronization is a bit messy and touches some internals
- *  of the routing table engine, because routing table maintenance is a typical
- *  example of the proverbial compatibility between different Unices and we want
- *  to keep the overhead of our krt business as low as possible and avoid maintaining
- *  a local routing table copy.
- *
- *  The kernel syncer can work in three different modes (according to system config header):
- *	o  Single routing table, single krt protocol.  [traditional Unix]
- *	o  Many routing tables, separate krt protocols for all of them.
- *	o  Many routing tables, but every scan includes all tables, so we start
- *	   separate krt protocols which cooperate with each other.  [Linux 2.2]
- *	   In this case, we keep only a single scan timer.
- *
- *  The hacky bits:
- *	o  We use FIB node flags to keep track of route synchronization status.
- *	o  When starting up, we cheat by looking if there is another kernel
- *	   krt instance to be initialized later and performing table scan
- *	   only once for all the instances.
- *	o  We attach temporary rte's to routing tables.
- *
- *  If you are brave enough, continue now.  You cannot say you haven't been warned.
- */
-
 static int krt_uptodate(rte *k, rte *e);
 
 /*

sysdep/unix/log.c

@@ -1,11 +1,18 @@
 /*
  *	BIRD Library -- Logging Functions
  *
- *	(c) 1998--1999 Martin Mares <mj@ucw.cz>
+ *	(c) 1998--2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
+/**
+ * DOC: Logging
+ *
+ * The Logging module offers a simple set of functions for writing
+ * messages to system logs and to the debug output.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
@@ -94,6 +101,16 @@ vlog(int class, char *msg, va_list args)
   cli_echo(class, buf);
 }
 
+/**
+ * log - log a message
+ * @msg: printf-like formatting string with message class information
+ * prepended (%L_DEBUG to %L_BUG, see |lib/birdlib.h|)
+ *
+ * This function formats a message according to the format string @msg
+ * and writes it to the corresponding logfile (as specified in the
+ * configuration). Please note that the message is automatically
+ * formatted as a full line, no need to include |\n| inside.
+ */
 void
 log(char *msg, ...)
 {
@@ -107,6 +124,13 @@ log(char *msg, ...)
   va_end(args);
 }
 
+/**
+ * bug - report an internal error
+ * @msg: a printf-like error message
+ *
+ * This function logs an internal error and aborts execution
+ * of the program.
+ */
 void
 bug(char *msg, ...)
 {
@@ -117,6 +141,13 @@ bug(char *msg, ...)
   abort();
 }
 
+/**
+ * bug - report a fatal error
+ * @msg: a printf-like error message
+ *
+ * This function logs a fatal error and aborts execution
+ * of the program.
+ */
 void
 die(char *msg, ...)
 {
@@ -127,6 +158,13 @@ die(char *msg, ...)
   exit(1);
 }
 
+/**
+ * debug - write to debug output
+ * @msg: a printf-like message
+ *
+ * This function formats the message @msg and prints it out
+ * to the debugging output. No newline character is appended.
+ */
 void
 debug(char *msg, ...)
 {