packages/systemd: fix double getty on console

When selecting "console" for the automatic getty, the buildroot logic
would collide with systemd's internal console detection logic, resulting
in two getty being started on the console.

This commit fixes that by doing nothing when "console" is selected and
letting systemd-getty-generator deal with starting the proper getty.

Note that if something other than the console is selected
* Things will work properly, even if the selected terminal is also the
  console
* A getty will still be started on the console.
  This is what systemd has been doing on buildroot since the beginning. it
  could be disabled but I left it for backward compatibility

Fixes: #12361
Signed-off-by: Jérémy Rosen <jeremy.rosen@smile.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 26c32d933eb4d841b7fbe9c1e0b61cef89665b15)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/systemd/systemd.mk

@@ -434,37 +434,42 @@ define SYSTEMD_USERS
 endef
 
 ifneq ($(call qstrip,$(BR2_TARGET_GENERIC_GETTY_PORT)),)
-# systemd needs getty.service for VTs and serial-getty.service for serial ttys
-# note that console-getty.service should be used on /dev/console as it should not have dependencies
-# also patch the file to use the correct baud-rate, the default baudrate is 115200 so look for that
+# systemd provides multiple units to autospawn getty as neede
+# * getty@.service to start a getty on normal TTY
+# * sertial-getty@.service to start a getty on serial lines
+# * console-getty.service for generic /dev/console
+# * container-getty@.service for a getty on /dev/pts/*
 #
-# systemd defaults to only have getty@tty.service enabled
-# * DefaultInstance=tty1 in getty@service
-# * no DefaultInstance in serial-getty@.service
-# * WantedBy=getty.target in console-getty.service
-# * console-getty is not enabled because of 90-systemd.preset
-# We want "systemctl preset-all" to do the right thing, even when run on the target after boot
-# * remove the default instance of getty@.service via a drop-in in /usr/lib
-# * set a new DefaultInstance for getty@.service instead, if needed
-# * set a new DefaultInstance for serial-getty@.service, if needed
-# * override the systemd-provided preset for console-getty.service if needed
+# the generator systemd-getty-generator will
+# * read the console= kernel command line parameter
+# * enable one of the above units depending on what it finds
+#
+# Systemd defaults to enablinb getty@tty1.service
+#
+# What we want to do
+# * Enable a getty on $BR2_TARGET_GENERIC_TTY_PATH
+# * Set the baudrate for all units according to BR2_TARGET_GENERIC_GETTY_BAUDRATE
+# * Always enable a getty on the console using systemd-getty-generator
+#   (backward compatibility with previous releases of buildroot)
+#
+# What we do
+# * disable getty@tty1 (enabled by upstream systemd)
+# * enable getty@xxx if  $BR2_TARGET_GENERIC_TTY_PATH is a tty
+# * enable serial-getty@xxx for other $BR2_TARGET_GENERIC_TTY_PATH
+# * rewrite baudrates if a baudrate is provided
 define SYSTEMD_INSTALL_SERVICE_TTY
 	mkdir $(TARGET_DIR)/usr/lib/systemd/system/getty@.service.d; \
 	printf '[Install]\nDefaultInstance=\n' \
 		>$(TARGET_DIR)/usr/lib/systemd/system/getty@.service.d/buildroot-console.conf; \
 	if [ $(BR2_TARGET_GENERIC_GETTY_PORT) = "console" ]; \
 	then \
-		TARGET="console-getty.service"; \
-		printf 'enable console-getty.service\n' \
-			>$(TARGET_DIR)/usr/lib/systemd/system-preset/81-buildroot-tty.preset; \
+		: ; \
 	elif echo $(BR2_TARGET_GENERIC_GETTY_PORT) | egrep -q 'tty[0-9]*$$'; \
 	then \
-		TARGET="getty@.service"; \
 		printf '[Install]\nDefaultInstance=%s\n' \
 			$(call qstrip,$(BR2_TARGET_GENERIC_GETTY_PORT)) \
 			>$(TARGET_DIR)/usr/lib/systemd/system/getty@.service.d/buildroot-console.conf; \
 	else \
-		TARGET="serial-getty@.service"; \
 		mkdir $(TARGET_DIR)/usr/lib/systemd/system/serial-getty@.service.d;\
 		printf '[Install]\nDefaultInstance=%s\n' \
 			$(call qstrip,$(BR2_TARGET_GENERIC_GETTY_PORT)) \
@@ -472,7 +477,10 @@ define SYSTEMD_INSTALL_SERVICE_TTY
 	fi; \
 	if [ $(call qstrip,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE)) -gt 0 ] ; \
 	then \
-		$(SED) 's,115200,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),' $(TARGET_DIR)/lib/systemd/system/$${TARGET}; \
+		$(SED) 's/115200/$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),115200/' $(TARGET_DIR)/lib/systemd/system/getty@.service; \
+		$(SED) 's/115200/$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),115200/' $(TARGET_DIR)/lib/systemd/system/serial-getty@.service; \
+		$(SED) 's/115200/$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),115200/' $(TARGET_DIR)/lib/systemd/system/console-getty@.service; \
+		$(SED) 's/115200/$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),115200/' $(TARGET_DIR)/lib/systemd/system/container-getty@.service; \
 	fi
 endef
 endif