[console speed] lock console speed to start up speed

Auto negotiating console speed could cause sonic to lock on a wrong
speed under rare conditions. The only way to come out of the wrong
speed is to issue line break or restart console service with forced
speed, or reboot sonic.

Lock down the console speed to avoid these situations.

Signed-off-by: Ying Xie <[email protected]>

Author: yxieca

files/image_config/platform/rc.local

@@ -128,6 +128,19 @@ process_reboot_cause() {
     echo "Unexpected reboot" > $REBOOT_CAUSE_FILE
 }
 
+program_console_speed()
+{
+    speed=$(cat /proc/cmdline | grep -Eo 'console=ttyS[0-9]+,[0-9]+' | cut -d "," -f2)
+    if [ -z "$speed" ]; then
+        CONSOLE_SPEED=9600
+    else
+        CONSOLE_SPEED=$speed
+    fi
+
+    sed -i "s|\-\-keep\-baud .* %I| $CONSOLE_SPEED %I|g" /lib/systemd/system/[email protected]
+    systemctl daemon-reload
+}
+
 #### Begin Main Body ####
 
 # Set up previous and next reboot cause files
@@ -209,6 +222,8 @@ fi
 
 . /host/machine.conf
 
+program_console_speed
+
 if [ -f $FIRST_BOOT_FILE ]; then
 
     echo "First boot detected. Performing first boot tasks..."