私はMacbookPro10,1（レティーナ）の誇り高い所有者です。私はそれにDebian stableをインストールし、今まで今日までうまくいきます。
grubをそのままにしてデフォルトモードで起動すると、表示テキストが表示されますが、ログイン画面は表示されません。最後の数行：
...
Started WPA Supplicant
Started User Manager for UID 103
リカバリモードで再起動し、ネットワーク管理者を起動でき、問題はありません。場合に備えて、nvidiaパッケージを再インストールしました（apt-get install -tstretch-backports nvidia-driver）。
だから私の目標は、gdm3が起動しない理由を診断することです。マイコンピュータでは、++キーまたは++キーがキーボードにないCtrlため使用できません。AltBackspaceAlt grPrint ScreenK
仮想ttyは使用できません（Ctrl+はF1プロンプトを表示しません）。
だから今ssh + PermitRootLoginをyesに設定しました。
リモートSSHで次のコマンドを試しても何も起こりません。
# service gdm3 restart
しかし、（私のリモートSSHでも）起動でき、startxリモートMacbookProでXセッションが正しく表示されることがわかります。
gdm3が起動していないことを確認する手順は何ですか？
ちなみに、私の以前の習慣はgrep /var/log/debugでしたが、今回は何も起こりませんでした。
# grep gdm3 /var/log/debug
Dec 13 12:35:33 macbookpro gdm3: Enabling debugging
Dec 13 12:35:33 macbookpro gdm3: Changing user:group to Debian-gdm:Debian-gdm
Dec 13 12:35:33 macbookpro gdm3: Successfully connected to D-Bus
Dec 13 12:35:33 macbookpro gdm3: GdmManager: GDM starting to manage displays
Dec 13 12:35:33 macbookpro gdm3: GdmLocalDisplayFactory: Adding display on seat seat0
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: id: (null)
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: seat id: (null)
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: session class: greeter
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: initial: no
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: allow timed login: yes
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: local: yes
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: session type: wayland
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: seat id: seat0
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: initial: yes
Dec 13 12:35:33 macbookpro gdm3: GdmDisplayStore: Adding display /org/gnome/DisplayManager/Displays/94531909767968 to store
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Managing display: /org/gnome/DisplayManager/Displays/94531909767968
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Preparing display: /org/gnome/DisplayManager/Displays/94531909767968
Dec 13 12:35:33 macbookpro gdm3: doing initial setup? no
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: prepare display
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Got automatic login details for display: 0
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Creating D-Bus server for worker for session
Dec 13 12:35:33 macbookpro gdm3: GdmSession: D-Bus server for workers listening on unix:abstract=/tmp/dbus-tddsFbEu
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Creating D-Bus server for greeters and such
Dec 13 12:35:33 macbookpro gdm3: GdmSession: D-Bus server for greeters listening on unix:abstract=/tmp/dbus-b3xo1lyn
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Setting display device: (null)
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Running greeter
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Creating greeter for (null) (null)
Dec 13 12:35:33 macbookpro gdm3: GdmLaunchEnvironment: Starting...
Dec 13 12:35:33 macbookpro gdm3: GdmLaunchEnvironment: Setting up run time dir /var/run/gdm3/greeter
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Creating D-Bus server for worker for session
Dec 13 12:35:33 macbookpro gdm3: GdmSession: D-Bus server for workers listening on unix:abstract=/tmp/dbus-vfQwpNon
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Creating D-Bus server for greeters and such
Dec 13 12:35:33 macbookpro gdm3: GdmSession: D-Bus server for greeters listening on unix:abstract=/tmp/dbus-BAYbCdhF
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Setting display device: (null)
Dec 13 12:35:33 macbookpro gdm3: GdmSession: starting conversation gdm-launch-environment
Dec 13 12:35:33 macbookpro gdm3: GdmSessionWorkerJob: Starting worker...
Dec 13 12:35:33 macbookpro gdm3: GdmSessionWorkerJob: Running session_worker_job process: gdm-session-worker [pam/gdm-launch-environment] /usr/lib/gdm3/gdm-session-worker
Dec 13 12:35:33 macbookpro gdm3: GdmSessionWorkerJob: : SessionWorkerJob on pid 2778
Dec 13 12:35:33 macbookpro gdm3: GdmSession: setting session to type 'wayland'
Dec 13 12:35:33 macbookpro gdm3: GdmLocalDisplayFactory: display status changed: 1
Dec 13 12:35:33 macbookpro gdm3: GdmDBusServer: new connection 0x55f9ece6d650
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Handling new connection from worker
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Authenticating new connection
Dec 13 12:35:33 macbookpro gdm3: GdmSession: worker connection is 0x55f9ece6d650
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Emitting conversation-started signal
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Beginning setup for session for program using PAM service gdm-launch-environment
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Conversation started
Dec 13 12:35:33 macbookpro gdm-launch-environment]: GdmSessionWorker: Set PAM environment variable: 'HOME=/var/lib/gdm3'
Dec 13 12:35:33 macbookpro gdm3: GdmSession: type wayland, program? yes, seat seat0
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Emitting 'session-opened' signal
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Greeter session opened
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: session id: c1
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Stopping all conversations except for gdm-launch-environment
Dec 13 12:35:33 macbookpro gdm3: GdmSession: type wayland, program? yes, seat seat0
Dec 13 12:35:33 macbookpro gdm3: GdmSession: type wayland, program? yes, seat seat0
Dec 13 12:35:33 macbookpro gdm-launch-environment]: GdmSessionWorker: Set PAM environment variable: 'HOME=/var/lib/gdm3'
Dec 13 12:35:33 macbookpro gdm-launch-environment]: GdmSessionWorker: Set PAM environment variable: 'PWD=/var/lib/gdm3'
Dec 13 12:35:33 macbookpro gdm-launch-environment]: GdmSessionWorker: start program: /usr/lib/gdm3/gdm-wayland-session "gnome-session --autostart /usr/share/gdm/greeter/autostart --debug"
Dec 13 12:35:33 macbookpro gdm-launch-environment]: GdmSessionWorker: opening session for program '/usr/lib/gdm3/gdm-wayland-session'
Dec 13 12:35:33 macbookpro gdm3: GdmSession: Emitting 'session-started' signal with pid '3287'
Dec 13 12:35:33 macbookpro gdm3: GdmDisplay: Greeter started
Dec 13 12:35:33 macbookpro gdm3: GdmManager: trying to register new display
Dec 13 12:35:33 macbookpro gdm3: GdmLocalDisplayFactory: display status changed: 2
また、参考として、ここでもエラーは表示されません。
# systemctl status gdm
● gdm.service - GNOME Display Manager
Loaded: loaded (/lib/systemd/system/gdm.service; static; vendor preset: enabled)
Active: active (running) since Thu 2018-12-13 12:35:33 CET; 5min ago
Process: 2600 ExecStartPre=/usr/share/gdm/generate-config (code=exited, status=0/SUCCESS)
Process: 2582 ExecStartPre=/bin/sh -c [ "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/gdm3" ] (code=exited, status=0/SUCCESS)
Main PID: 2626 (gdm3)
Tasks: 3 (limit: 4915)
CGroup: /system.slice/gdm.service
└─2626 /usr/sbin/gdm3
Dec 13 12:40:06 macbookpro gdm-launch-environment][9098]: GdmSession worker: watching pid 9101
Dec 13 12:40:06 macbookpro gdm3[2626]: GdmSession: Emitting 'session-started' signal with pid '9101'
Dec 13 12:40:06 macbookpro gdm3[2626]: GdmDisplay: Greeter started
Dec 13 12:40:08 macbookpro gdm3[2626]: GdmManager: trying to register new display
Dec 13 12:40:08 macbookpro gdm3[2626]: GdmLocalDisplayFactory: display status changed: 2
Dec 13 12:40:13 macbookpro gdm3[2626]: GdmManager: trying to open new session
Dec 13 12:40:13 macbookpro gdm3[2626]: GdmDBusServer: new connection 0x55f9ece6db50
Dec 13 12:40:13 macbookpro gdm3[2626]: GdmSession: Handling new connection from outside
Dec 13 12:40:13 macbookpro gdm3[2626]: GdmManager: client connected
Dec 13 12:40:13 macbookpro gdm3[2626]: GdmDisplay: Got timed login details for display: 0