X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fcore%2Fspecial.h;h=99c0e1222e6764b9af914428bcc62b3cbd066fb5;hb=d2f1f23ad2636cf05589a67b5229c7fd604bc21f;hp=8923f340ba4f3e93f4f2bef21e5688e5410e2438;hpb=6524990fdc98370ecba5d9f73e67161e8798c010;p=elogind.git

diff --git a/src/core/special.h b/src/core/special.h
index 8923f340b..99c0e1222 100644
--- a/src/core/special.h
+++ b/src/core/special.h
@@ -46,7 +46,7 @@
 /* Early boot targets */
 #define SPECIAL_SYSINIT_TARGET "sysinit.target"
 #define SPECIAL_SOCKETS_TARGET "sockets.target"
-#define SPECIAL_LOCAL_FS_TARGET "local-fs.target"         /* LSB's $local_fs */
+#define SPECIAL_LOCAL_FS_TARGET "local-fs.target"
 #define SPECIAL_LOCAL_FS_PRE_TARGET "local-fs-pre.target"
 #define SPECIAL_REMOTE_FS_TARGET "remote-fs.target"       /* LSB's $remote_fs */
 #define SPECIAL_REMOTE_FS_PRE_TARGET "remote-fs-pre.target"
@@ -57,11 +57,33 @@
 #define SPECIAL_NETWORK_TARGET "network.target"           /* LSB's $network */
 #define SPECIAL_NSS_LOOKUP_TARGET "nss-lookup.target"     /* LSB's $named */
 #define SPECIAL_RPCBIND_TARGET "rpcbind.target"           /* LSB's $portmap */
-#define SPECIAL_SYSLOG_TARGET "syslog.target"             /* LSB's $syslog */
 #define SPECIAL_TIME_SYNC_TARGET "time-sync.target"       /* LSB's $time */
-#define SPECIAL_DISPLAY_MANAGER_SERVICE "display-manager.service"       /* Debian's $x-display-manager */
-#define SPECIAL_MAIL_TRANSFER_AGENT_TARGET "mail-transfer-agent.target" /* Debian's $mail-{transport|transfer-agent */
-#define SPECIAL_HTTP_DAEMON_TARGET "http-daemon.target"
+
+/*
+ * Rules regarding adding further high level targets like the above:
+ *
+ * - Be conservative, only add more of these when we really need
+ *   them. We need strong usecases for further additions.
+ *
+ * - When there can be multiple implementations running side-by-side,
+ *   it needs to be a .target unit which can pull in all
+ *   implementations.
+ *
+ * - If something can be implemented with socket activation, and
+ *   without, it needs to be a .target unit, so that it can pull in
+ *   the appropriate unit.
+ *
+ * - Otherwise, it should be a .service unit.
+ *
+ * - In some cases it is OK to have both a .service and a .target
+ *   unit, i.e. if there can be multiple parallel implementations, but
+ *   only one is the "system" one. Example: syslog.
+ *
+ * Or to put this in other words: .service symlinks can be used to
+ * arbitrate between multiple implementations if there can be only one
+ * of a kind. .target units can be used to support multiple
+ * implementations that can run side-by-side.
+ */
 
 /* Magic early boot services */
 #define SPECIAL_FSCK_SERVICE "systemd-fsck@.service"