[Buildroot] [PATCH v3 1/1] package/systemd: fix "Timed out waiting for device /dev/console."

[Xavier Ruppen <xruppen@gmail.com>]

Buildroot built with systemd fails to open a login prompt on the
serial port when /dev/console is specified as BR2_TARGET_GENERIC_GETTY_PORT
(which is its default value):

systemd[1]: dev-console.device: Job dev-console.device/start timed out.
systemd[1]: Timed out waiting for device /dev/console.
systemd[1]: Dependency failed for Serial Getty on console.
systemd[1]: serial-getty at console.service: Job serial-getty at console.service/start failed with result 'dependency'.
systemd[1]: dev-console.device: Job dev-console.device/start failed with result 'timeout'.
systemd[1]: Reached target Login Prompts.
systemd[1]: Reached target Multi-User System.

According to this issue on Github [1], serial-getty at .service should
not be instantiated on /dev/console, console-getty at .service should
be used instead. This stems from the fact that there should be no
dependency on /dev/console.

[1] https://github.com/systemd/systemd/issues/10914

Signed-off-by: Xavier Ruppen <xruppen@gmail.com>
---

 Changes v2 -> v3:
  - introduce two separate variables, $TARGET and $LINK_NAME,
    in order to solve various '@' problems.
  - I tested this patch with console and serial-getty. I also
    checked that sed works when changing the baudrate:

    $ ls -al output/target/etc/systemd/system/getty.target.wants/
    total 8
    drwxr-xr-x 2 user user 4096 Mar  4 20:09 .
    drwxr-xr-x 8 user user 4096 Mar  4 20:09 ..
    lrwxrwxrwx 1 user user   52 Mar  4 20:09 console-getty.service -> ../../../../lib/systemd/system/console-getty.service
    
    $ ls -al output/target/etc/systemd/system/getty.target.wants/
    total 8
    drwxr-xr-x 2 user user 4096 Mar  4 20:12 .
    drwxr-xr-x 8 user user 4096 Mar  4 20:12 ..
    lrwxrwxrwx 1 user user   45 Mar  4 20:12 getty at serial-getty.service -> ../../../../lib/systemd/system/getty at .service

 Changes v1 -> v2:
  - swap tty and console if statements
  - use equality operator instead of grep for "console"

 package/systemd/systemd.mk | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/package/systemd/systemd.mk b/package/systemd/systemd.mk
index 7a46a50ed3..1d0141f20b 100644
--- a/package/systemd/systemd.mk
+++ b/package/systemd/systemd.mk
@@ -397,19 +397,29 @@ 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
 define SYSTEMD_INSTALL_SERVICE_TTY
-	if echo $(BR2_TARGET_GENERIC_GETTY_PORT) | egrep -q 'tty[0-9]*$$'; \
+	if [ $(BR2_TARGET_GENERIC_GETTY_PORT) = "console" ]; \
+	then \
+		SERVICE="console-getty"; \
+		TARGET=$${SERVICE}.service; \
+		LINK_NAME=$${SERVICE}.service; \
+	elif echo $(BR2_TARGET_GENERIC_GETTY_PORT) | egrep -q 'tty[0-9]*$$'; \
 	then \
 		SERVICE="getty"; \
+		TARGET=$${SERVICE}@.service; \
+		LINK_NAME=$${SERVICE}@$(BR2_TARGET_GENERIC_GETTY_PORT).service; \
 	else \
 		SERVICE="serial-getty"; \
+		TARGET=$${SERVICE}@.service; \
+		LINK_NAME=$${SERVICE}@$(BR2_TARGET_GENERIC_GETTY_PORT).service; \
 	fi; \
-	ln -fs ../../../../lib/systemd/system/$${SERVICE}@.service \
-		$(TARGET_DIR)/etc/systemd/system/getty.target.wants/$${SERVICE}@$(BR2_TARGET_GENERIC_GETTY_PORT).service; \
+	ln -fs ../../../../lib/systemd/system/$${TARGET} \
+		$(TARGET_DIR)/etc/systemd/system/getty.target.wants/$${LINK_NAME}; \
 	if [ $(call qstrip,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE)) -gt 0 ] ; \
 	then \
-		$(SED) 's,115200,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),' $(TARGET_DIR)/lib/systemd/system/$${SERVICE}@.service; \
+		$(SED) 's,115200,$(BR2_TARGET_GENERIC_GETTY_BAUDRATE),' $(TARGET_DIR)/lib/systemd/system/$${TARGET}; \
 	fi
 endef
 endif
-- 
2.21.0