systemd: enable switch debug-tty to provide a debug console

This allows us to use the default debug-shell.service provided
by systemd and cut down on custom made services. This will also
always provide a debug shell as there is no reason we shouldn't
have access to one.

distributions/LibreELEC/options

@@ -225,3 +225,5 @@
 # IR remote keymaps supported in default config
   IR_REMOTE_KEYMAPS="rc6_mce xbox_360 xbox_one"
 
+# debug tty path
+  DEBUG_TTY="/dev/tty3"

packages/sysutils/busybox/package.mk

@@ -177,7 +177,6 @@ post_install() {
   add_user nobody x 65534 65534 "Nobody" "/" "/bin/sh"
   add_group nogroup 65534
 
-  enable_service debug-shell.service
   enable_service shell.service
   enable_service show-version.service
   enable_service var.mount

packages/sysutils/systemd/package.mk

@@ -88,7 +88,8 @@ PKG_MESON_OPTS_TARGET="--libdir=/usr/lib \
                        -Dzshcompletiondir=no \
                        -Dkmod-path=/usr/bin/kmod \
                        -Dmount-path=/usr/bin/mount \
-                       -Dumount-path=/usr/bin/umount"
+                       -Dumount-path=/usr/bin/umount \
+                       -Ddebug-tty=$DEBUG_TTY"
 
 pre_configure_target() {
   export CFLAGS="$CFLAGS -fno-schedule-insns -fno-schedule-insns2 -Wno-format-truncation"
@@ -127,9 +128,6 @@ post_makeinstall_target() {
   safe_remove $INSTALL/usr/lib/udev/rules.d/71-seat.rules
   safe_remove $INSTALL/usr/lib/udev/rules.d/73-seat-late.rules
 
-  # remove debug-shell.service, we install our own
-  safe_remove $INSTALL/usr/lib/systemd/system/debug-shell.service
-
   # remove getty units, we dont want a console
   safe_remove $INSTALL/usr/lib/systemd/system/[email protected]
   safe_remove $INSTALL/usr/lib/systemd/system/console-getty.service
@@ -258,4 +256,5 @@ post_install() {
   enable_service usercache.service
   enable_service kernel-overlays.service
   enable_service hwdb.service
+  enable_service debug-shell.service
 }

projects/Allwinner/options

@@ -85,3 +85,7 @@
 
   # build with installer (yes / no)
     INSTALLER_SUPPORT="no"
+
+  # debug tty path
+    DEBUG_TTY="/dev/console"
+

projects/RPi/options

@@ -137,3 +137,6 @@
   # for a list of additional drivers see packages/linux-driver-addons
   # Space separated list is supported,
     DRIVER_ADDONS="crazycat dvb-latest"
+
+  # debug tty path
+    DEBUG_TTY="/dev/console"

projects/Rockchip/options

@@ -85,3 +85,6 @@
   # for a list of additinoal drivers see packages/linux-driver-addons
   # Space separated list is supported,
     DRIVER_ADDONS="crazycat dvb-latest"
+
+  # debug tty path
+    DEBUG_TTY="/dev/ttyS2"