pcu_main: Mark -r cmdline param as deprecated

We have VTY support for it enabled in osmo-pcu since a while ago. Let's
mark it as depcreated now so that we can drop this cmdline arg in the
future.

Change-Id: Ic39c94984cb311aac0464d69f564af6d5447bd0f

doc/manuals/chapters/running.adoc

@@ -21,12 +21,6 @@ options:
 	Specify the file and path name of the configuration file to be
 	used. If none is specified, use `osmo-pcu.cfg` in the current
 	working directory.
-*-r, --realtime 'PRIO'*::
-	Enable use of the Linux kernel realtime priority scheduler with
-	the specified priority.
-	It is recommended you use this option on low-performance
-	embedded systems or systems that encounter high non-GSM/GPRS
-	load.
 *-m, --mcc 'MCC'*::
 	Use the given MCC instead of that provided by BTS via PCU socket
 *-n, --mnc 'MNC'*::

src/pcu_main.cpp

@@ -74,7 +74,6 @@ static void print_help()
 		"  -m	--mcc MCC		Use given MCC instead of value provided by BTS\n"
 		"  -n	--mnc MNC		Use given MNC instead of value provided by BTS\n"
 		"  -V	--version		Print version\n"
-		"  -r	--realtime PRIO		Use SCHED_RR with the specified priority\n"
 		"  -D	--daemonize		Fork the process into a background daemon\n"
 		"  -i	--gsmtap-ip		The destination IP used for GSMTAP\n"
 		"\nVTY reference generation:\n"
@@ -165,6 +164,8 @@ static void handle_options(int argc, char **argv)
 			break;
 		case 'r':
 			rt_prio = atoi(optarg);
+			fprintf(stderr, "Command line argument '-r' is deprecated, use VTY "
+				"cpu-sched node setting 'policy rr %d' instead.\n", rt_prio);
 			break;
 		case 'D':
 			daemonize = true;