在qemu中，登录是可以的。但是当我尝试在fpga中使用ubuntu rootfs时，/dev/ttyS0会超时。顺便说一句，最后登录服务失败了。ttyS0服务会导致登录服务失败吗？
Welcome to Ubuntu 20.04 LTS!
[ 593.585413] systemd[1]: Set hostname to <hobot>.
[ 699.037204] systemd[1]: /lib/systemd/system/gpsd.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/gpsd.sock → /run/gpsd.sock; please update the unit file accordingly.
[ 699.112901] systemd[1]: Binding to IPv6 address not available since kernel does not support IPv6.
[ 706.549827] systemd[1]: /lib/systemd/system/dbus.socket:5: ListenStream= references a path below legacy directory /var/run/, updating /var/run/dbus/system_bus_socket → /run/dbus/system_bus_socket; please update the unit file accordingly.
[ 708.200900] systemd[1]: Created slice system-getty.slice.
[ OK ] Created slice system-getty.slice.
[ 708.489113] systemd[1]: Created slice system-modprobe.slice.
[ OK ] Created slice system-modprobe.slice.
[ 708.734143] systemd[1]: Created slice system-serial\x2dgetty.slice.
[ OK ] Created slice system-serial\x2dgetty.slice.
[ 708.952110] systemd[1]: Created slice User and Session Slice.
[ OK ] Created slice User and Session Slice.
[ 709.082221] systemd[1]: Started Dispatch Password Requests to Console Directory Watch.
[ OK ] Started Dispatch Password …ts to Console Directory Watch.
[ 709.205230] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[ OK ] Started Forward Password R…uests to Wall Directory Watch.
[ 709.311796] systemd[1]: Condition check resulted in Arbitrary Executable File Formats File System Automount Point being skipped.
[ 709.351265] systemd[1]: Reached target Local Encrypted Volumes.
[ OK ] Reached target Local Encrypted Volumes.
[ 709.420379] systemd[1]: Reached target Local File Systems.
[ OK ] Reached target Local File Systems.
[ 709.476117] systemd[1]: Reached target Paths.
[ OK ] Reached target Paths.
[ 709.529575] systemd[1]: Reached target Remote File Systems.
[ OK ] Reached target Remote File Systems.
[ 709.573451] systemd[1]: Reached target Slices.
[ OK ] Reached target Slices.
[ 709.633579] systemd[1]: Reached target Swap.
[ OK ] Reached target Swap.
[ 709.687071] systemd[1]: Reached target System Time Set.
[ OK ] Reached target System Time Set.
[ 709.780783] systemd[1]: Listening on initctl Compatibility Named Pipe.
[ OK ] Listening on initctl Compatibility Named Pipe.
[ 709.990045] systemd[1]: Listening on Journal Audit Socket.
[ OK ] Listening on Journal Audit Socket.
[ 710.132600] systemd[1]: Listening on Journal Socket (/dev/log).
[ OK ] Listening on Journal Socket (/dev/log).
[ 710.266438] systemd[1]: Listening on Journal Socket.
[ OK ] Listening on Journal Socket.
[ 710.409795] systemd[1]: Listening on udev Control Socket.
[ OK ] Listening on udev Control Socket.
[ 710.510228] systemd[1]: Listening on udev Kernel Socket.
[ OK ] Listening on udev Kernel Socket.
[ 710.616757] systemd[1]: Condition check resulted in Huge Pages File System being skipped.
[ 712.175643] systemd[1]: Mounting POSIX Message Queue File System...
Mounting POSIX Message Queue File System...
[ 715.847996] systemd[1]: Mounting Kernel Debug File System...
Mounting Kernel Debug File System...
[ 716.675990] systemd[1]: Condition check resulted in Kernel Trace File System being skipped.
[ 722.790069] systemd[1]: Starting Journal Service...
Starting Journal Service...
[ 723.155893] systemd[1]: Condition check resulted in Create list of static device nodes for the current kernel being skipped.
[ 723.343577] systemd[1]: Condition check resulted in Load Kernel Module drm being skipped.
[ 724.047826] systemd[1]: Condition check resulted in Set Up Additional Binary Formats being skipped.
[ 724.461414] systemd[1]: Condition check resulted in Rebuild Hardware Database being skipped.
[ 724.687463] systemd[1]: Condition check resulted in Commit a transient machine-id on disk being skipped.
[ 729.325753] systemd[1]: Starting Load Kernel Modules...
Starting Load Kernel Modules...
[ 730.203318] systemd[1]: Condition check resulted in Platform Persistent Storage Archival being skipped.
[ 736.540544] systemd[1]: Starting Load/Save Random Seed...
Starting Load/Save Random Seed...
[ 746.672157] systemd[1]: Starting Create System Users...
Starting Create System Users...
[ 762.714644] systemd[1]: Starting udev Coldplug all Devices...
Starting udev Coldplug all Devices...
[ 779.070595] systemd[1]: Mounted POSIX Message Queue File System.
[ OK ] Mounted POSIX Message Queue File System.
[ 782.789113] systemd[1]: Mounted Kernel Debug File System.
[ OK ] Mounted Kernel Debug File System.
[ *** ] (4 of 6) A start job is running for /dev/ttyS0 (1min 31s / 1min 32s)
[ 800.187428] systemd[1]: dev-ttyS0.device: Job dev-ttyS0.device/start timed out.
[ TIME ] Timed out waiting for device /dev/ttyS0.
[ 801.487978] systemd[1]: Dependency failed for Serial Getty on ttyS0.
[DEPEND] Dependency failed for Serial Getty on ttyS0.
[ 802.475959] systemd[1]: [email protected]: Job [email protected]/start failed with result 'dependency'.
[ 802.766200] systemd[1]: dev-ttyS0.device: Job dev-ttyS0.device/start failed with result 'timeout'.
[ 810.989177] systemd[1]: Finished Load Kernel Modules.
[ OK ] Finished Load Kernel Modules.
[ 819.221695] systemd[1]: Finished Load/Save Random Seed.
[ OK ] Finished Load/Save Random Seed.
[ 821.782376] systemd[1]: systemd-journald.service: start operation timed out. Terminating.
[ *** ] (1 of 3) A start job is running for…rnal Service (1min 55s / 3min 25s)
[ 824.098551] systemd[1]: Condition check resulted in FUSE Control File System being skipped.
[ 824.707863] systemd[1]: Condition check resulted in Kernel Configuration File System being skipped.
[ 825.035808] systemd[1]: Condition check resulted in Store a System Token in an EFI Variable being skipped.
Starting Apply Kernel Variables...
[*** ] (1 of 4) A start job is running for…rnal Service (2min 11s / 3min 25s)
[** ] (1 of 4) A start job is running for…rnal Service (2min 13s / 3min 25s)
[ 843.290510] systemd[1]: systemd-sysusers.service: Main process exited, code=killed, status=15/TERM
[ 843.982300] systemd[1]: systemd-sysusers.service: Failed with result 'timeout'.
[FAILED] Failed to start Create System Users.
See 'systemctl status systemd-sysusers.service' for details.
[ 860.001854] systemd-journald[322]: Received SIGTERM from PID 1 (systemd).
[ 861.482120] systemd[1]: Starting Create Static Device Nodes in /dev...
Starting Create Static Device Nodes in /dev...
[ 868.460095] systemd[1]: systemd-journald.service: Failed with result 'timeout'.
[ 871.500748] systemd[1]: Failed to start Journal Service.
[FAILED] Failed to start Journal Service.
See 'systemctl status systemd-journald.service' for details.
[ 872.614280] systemd[1]: Dependency failed for Flush Journal to Persistent Storage.
[DEPEND] Dependency failed for Flus…Journal to Persistent Storage.
[ 873.085379] systemd[1]: systemd-journal-flush.service: Job systemd-journal-flush.service/start failed with result 'dependency'.
[ 876.126004] systemd[1]: systemd-journald.service: Scheduled restart job, restart counter is at 1.
[* ] (2 of 3) A start job is running for…odes in /dev (2min 49s / no limit)
[ OK ] Stopped Journal Service.
[ 887.660593] systemd[1]: Starting Journal Service...
Starting Journal Service...
[ OK ] Finished Apply Kernel Variables.
[ OK ] Finished Create Static Device Nodes in /dev.
Starting udev Kernel Device Manager...
[ OK ] Started Journal Service.
Starting Create Volatile Files and Directories...
[ OK ] Started udev Kernel Device Manager.
[ OK ] Finished Create Volatile Files and Directories.
Starting Network Name Resolution...
Starting Update UTMP about System Boot/Shutdown...
[FAILED] Failed to start Network Name Resolution.
See 'systemctl status systemd-resolved.service' for details.
[ OK ] Stopped Network Name Resolution.
Starting Network Name Resolution...
[ OK ] Finished Update UTMP about System Boot/Shutdown.
[FAILED] Failed to start Network Name Resolution.
See 'systemctl status systemd-resolved.service' for details.
[ OK ] Stopped Network Name Resolution.
Starting Network Name Resolution...
[ OK ] Finished udev Coldplug all Devices.
[FAILED] Failed to start Network Name Resolution.
See 'systemctl status systemd-resolved.service' for details.
[ OK ] Reached target System Initialization.
[ OK ] Started Daily Cleanup of Temporary Directories.
[ OK ] Listening on D-Bus System Message Bus Socket.
[ OK ] Listening on GPS (Global P…ioning System) Daemon Sockets.
[ OK ] Reached target Sockets.
[ OK ] Reached target Basic System.
[ OK ] Started D-Bus System Message Bus.
Starting Network Manager...
Starting Remove Stale Onli…t4 Metadata Check Snapshots...
Starting Modify fstab and mount filesystems...
Starting Hobot log daemon...
Starting Login Service...
[ OK ] Stopped Network Name Resolution.
Starting Network Name Resolution...
Starting WPA supplicant...
[FAILED] Failed to start Network Manager.
See 'systemctl status NetworkManager.service' for details.
[FAILED] Failed to start Login Service.
See 'systemctl status systemd-logind.service' for details.
[FAILED] Failed to start Network Name Resolution.
See 'systemctl status systemd-resolved.service' for details.
[FAILED] Failed to start WPA supplicant.
See 'systemctl status wpa_supplicant.service' for details.
[ *** ] (1 of 3) A start job is running for… log daemon (26min 27s / no limit)