自从在我的联想 Flex2 Pro 15 上安装 Ubuntu 20.04 以来，从按下电源按钮到屏幕上出现 LENOVO 徽标的时间异常长，超过 30 秒。在此期间屏幕完全是黑色的。
当 LENOVO 徽标最终显示出来后，Ubuntu 徽标紧随其后，启动顺序按预期进行。速度不是特别快，但还不错。
当我安装 Ubuntu 18.04 时情况并非如此（它在启动时没有显示 LENOVO 徽标），所以我怀疑新的徽标功能可能与此问题有关。
我确实启用了 SecureBoot，但我不确定这是否相关。我记得我在 18.04 上也启用了 SecureBoot，但正如所说，我没有遇到启动缓慢的问题。
此外，当我在屏幕黑屏期间按下任意键（F2/Setup 或 F12/Boot 菜单除外）时，屏幕都会无限期地保持黑屏状态并且系统似乎挂起了。
输出systemd-analyze blame：
5.177s plymouth-quit-wait.service
4.186s NetworkManager-wait-online.service
3.374s dev-sda2.device
2.362s dev-loop10.device
2.317s dev-loop8.device
2.231s dev-loop9.device
2.227s snapd.service
2.216s dev-loop11.device
2.146s dev-loop14.device
2.111s dev-loop15.device
2.103s dev-loop13.device
2.074s dev-loop16.device
2.059s dev-loop12.device
2.047s dev-loop18.device
2.036s dev-loop17.device
2.033s dev-loop19.device
2.028s dev-loop20.device
1.916s [email protected]
1.871s dev-loop3.device
1.862s dev-loop2.device
1.858s dev-loop23.device
1.841s dev-loop25.device
1.826s dev-loop21.device
1.811s dev-loop26.device
1.807s dev-loop24.device
1.798s dev-loop22.device
1.765s dev-loop4.device
1.735s dev-loop5.device
1.723s dev-loop27.device
1.699s dev-loop1.device
1.677s dev-loop0.device
1.672s dev-loop7.device
1.649s dev-loop29.device
1.611s dev-loop6.device
1.602s dev-loop31.device
1.597s dev-loop28.device
1.585s dev-loop30.device
1.350s systemd-journal-flush.service
1.255s snap-speedy\x2dduplicate\x2dfinder-22.mount
1.254s snap-speedy\x2dduplicate\x2dfinder-27.mount
1.217s snap-snapd-8790.mount
1.194s snap-warzone2100-1573.mount
1.156s snap-scrcpy-238.mount
1.071s snap-warzone2100\x2dvideos-2.mount
1.067s snap-keepassxc-1006.mount
1.064s systemd-udevd.service
1.052s snap-obs\x2dstudio-1090.mount
1.044s snap-scrcpy-243.mount
1.032s snap-snapd-8542.mount
1.010s snap-snap\x2dstore-467.mount
986ms networkd-dispatcher.service
972ms systemd-rfkill.service
875ms snap-gnome\x2d3\x2d34\x2d1804-36.mount
863ms snap-kde\x2dframeworks\x2d5\x2dcore18-32.mount
847ms snap-signal\x2ddesktop-326.mount
809ms snap-sweethome3d\x2dhomedesign-9.mount
747ms snap-keepassxc-978.mount
746ms snap-minetest-1521.mount
657ms snap-minetest-1619.mount
628ms snap-snap\x2dstore-454.mount
621ms udisks2.service
597ms snap-core18-1880.mount
595ms snap-obs\x2dstudio-1118.mount
585ms snap-signal\x2ddesktop-327.mount
564ms snap-core-9665.mount
559ms [email protected]
555ms snap-gtk\x2dcommon\x2dthemes-1506.mount
550ms snap-canonical\x2dlivepatch-95.mount
544ms snap-intellij\x2didea\x2dcommunity-249.mount
511ms snap-core-9804.mount
473ms snap-gnome\x2d3\x2d28\x2d1804-128.mount
466ms accounts-daemon.service
455ms systemd-logind.service
446ms plymouth-read-write.service
417ms snap-intellij\x2didea\x2dcommunity-246.mount
372ms snap-core18-1885.mount
332ms upower.service
326ms NetworkManager.service
287ms snap-gimp-281.mount
287ms snap-gimp-292.mount
280ms snapper-boot.service
277ms systemd-resolved.service
276ms fwupd.service
259ms avahi-daemon.service
252ms bluetooth.service
224ms apport.service
223ms polkit.service
215ms motd-news.service
207ms snapd.apparmor.service
197ms ModemManager.service
195ms systemd-timesyncd.service
193ms switcheroo-control.service
185ms systemd-sysctl.service
184ms plymouth-start.service
180ms wpa_supplicant.service
179ms thermald.service
176ms grub-common.service
168ms gpu-manager.service
165ms rsyslog.service
162ms systemd-journald.service
160ms [email protected]
158ms systemd-modules-load.service
154ms secureboot-db.service
150ms e2scrub_reap.service
147ms grub-initrd-fallback.service
123ms colord.service
120ms systemd-sysusers.service
110ms apparmor.service
109ms systemd-random-seed.service
109ms keyboard-setup.service
102ms systemd-fsck@dev-disk-by\x2duuid-EBBB\x2d0E8C.service
98ms home.mount
96ms systemd-udev-trigger.service
91ms teamviewerd.service
82ms snapd.seeded.service
77ms systemd-tmpfiles-setup-dev.service
77ms gdm.service
55ms systemd-update-utmp.service
53ms pppd-dns.service
47ms kerneloops.service
46ms rtkit-daemon.service
44ms systemd-tmpfiles-setup.service
43ms systemd-fsck@dev-disk-by\x2duuid-139a2ef0\x2d2474\x2d484d\x2dbde8\x2d192ade6e4696.service
36ms openvpn.service
33ms run-rpc_pipefs.mount
29ms alsa-restore.service
28ms [email protected]
27ms rpcbind.service
26ms systemd-remount-fs.service
23ms systemd-tmpfiles-clean.service
22ms systemd-user-sessions.service
22ms [email protected]
20ms boot-efi.mount
19ms dev-hugepages.mount
19ms setvtrgb.service
18ms dev-mqueue.mount
16ms ufw.service
16ms sys-kernel-debug.mount
15ms sys-kernel-tracing.mount
14ms systemd-update-utmp-runlevel.service
12ms systemd-backlight@backlight:intel_backlight.service
11ms kmod-static-nodes.service
10ms console-setup.service
9ms nfs-config.service
5ms sys-fs-fuse-connections.mount
3ms sys-kernel-config.mount
3ms swapfile.swap
2ms postfix.service
1ms snapd.socket
输出systemd-analyze critical-chain：
The time when unit became active or started is printed after the "@" character.
The time the unit took to start is printed after the "+" character.
graphical.target @10.836s
└─multi-user.target @10.836s
└─postfix.service @10.833s +2ms
└─[email protected] @8.915s +1.916s
└─network-online.target @8.912s
└─NetworkManager-wait-online.service @4.724s +4.186s
└─NetworkManager.service @4.396s +326ms
└─dbus.service @4.385s
└─basic.target @4.362s
└─sockets.target @4.362s
└─snapd.socket @4.361s +1ms
└─sysinit.target @4.357s
└─snapd.apparmor.service @4.006s +207ms
└─apparmor.service @3.894s +110ms
└─local-fs.target @3.892s
└─run-snapd-ns-canonical\x2dlivepatch.mnt.mount @5.516s
└─run-snapd-ns.mount @5.048s
└─local-fs-pre.target @638ms
└─systemd-tmpfiles-setup-dev.service @560ms +77ms
└─systemd-sysusers.service @438ms +120ms
└─systemd-remount-fs.service @406ms +26ms
└─systemd-journald.socket @390ms
└─system.slice @382ms
└─-.slice @382ms