Fix netconsole: disable before reconfiguring.

Configfs params can't be modified while the target is enabled.
Disable first if already enabled, then reconfigure and re-enable.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

hosts/beefy/default.nix

@@ -37,12 +37,17 @@
       RemainAfterExit = true;
     };
     script = ''
-      mkdir -p /sys/kernel/config/netconsole/target1
-      echo enp1s0 > /sys/kernel/config/netconsole/target1/dev_name
-      echo 192.168.1.2 > /sys/kernel/config/netconsole/target1/remote_ip
-      echo 6666 > /sys/kernel/config/netconsole/target1/remote_port
-      echo c0:3f:d5:62:55:bb > /sys/kernel/config/netconsole/target1/remote_mac
-      echo 1 > /sys/kernel/config/netconsole/target1/enabled
+      TARGET=/sys/kernel/config/netconsole/target1
+      mkdir -p $TARGET
+      # Disable first if already enabled (can't modify params while enabled)
+      if [ -f $TARGET/enabled ] && [ "$(cat $TARGET/enabled)" = "1" ]; then
+        echo 0 > $TARGET/enabled
+      fi
+      echo enp1s0 > $TARGET/dev_name
+      echo 192.168.1.2 > $TARGET/remote_ip
+      echo 6666 > $TARGET/remote_port
+      echo c0:3f:d5:62:55:bb > $TARGET/remote_mac
+      echo 1 > $TARGET/enabled
     '';
   };