自己使用的ThinkPad T440最近经常在启动的时候卡住,出现如下图的情况，然后一直卡住。
多次尝试之后，偶尔可以进入系统，进入系统后，观察内核日志，有如下输出：
$ cat /var/log/kern.log.1 | grep failed Feb 18 15:27:04 longsky-ThinkPad-T440 kernel: [23109.811443] wlan0: failed to remove key (1, ff:ff:ff:ff:ff:ff) from hardware (-22) Feb 18 15:27:04 longsky-ThinkPad-T440 kernel: [23109.811564] wlan0: failed to remove key (2, ff:ff:ff:ff:ff:ff) from hardware (-22) Feb 19 17:16:49 longsky-ThinkPad-T440 kernel: [23123.591918] usb 2-7:1.0: rebind failed: -517 Feb 19 17:16:49 longsky-ThinkPad-T440 kernel: [23123.591932] usb 2-7:1.1: rebind failed: -517 Mar 5 05:10:28 longsky-ThinkPad-T440 kernel: [ 0.191509] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 5 05:10:28 longsky-ThinkPad-T440 kernel: [ 0.270510] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 5 05:10:28 longsky-ThinkPad-T440 kernel: [ 0.462860] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 5 05:10:32 longsky-ThinkPad-T440 kernel: [ 13.847807] vboxdrv: module verification failed: signature and/or required key missing - tainting kernel Mar 4 21:38:54 longsky-ThinkPad-T440 kernel: [ 0.124199] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 4 21:38:54 longsky-ThinkPad-T440 kernel: [ 0.152437] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 4 21:38:54 longsky-ThinkPad-T440 kernel: [ 0.237710] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 4 21:38:54 longsky-ThinkPad-T440 kernel: [ 6.288911] nvidia: module verification failed: signature and/or required key missing - tainting kernel Mar 4 21:55:24 longsky-ThinkPad-T440 kernel: [ 0.124085] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 4 21:55:24 longsky-ThinkPad-T440 kernel: [ 0.148564] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 4 21:55:24 longsky-ThinkPad-T440 kernel: [ 0.233590] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 4 21:55:24 longsky-ThinkPad-T440 kernel: [ 6.418571] nvidia: module verification failed: signature and/or required key missing - tainting kernel Mar 17 17:00:15 longsky-ThinkPad-T440 kernel: [ 0.120164] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 17 17:00:15 longsky-ThinkPad-T440 kernel: [ 0.148509] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 17 17:00:15 longsky-ThinkPad-T440 kernel: [ 0.233570] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 17 17:00:15 longsky-ThinkPad-T440 kernel: [ 6.192646] nvidia: module verification failed: signature and/or required key missing - tainting kernel Mar 17 17:10:37 longsky-ThinkPad-T440 kernel: [ 0.124261] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 17 17:10:37 longsky-ThinkPad-T440 kernel: [ 0.152503] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 17 17:10:37 longsky-ThinkPad-T440 kernel: [ 0.237826] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 17 17:10:37 longsky-ThinkPad-T440 kernel: [ 6.545499] nvidia: module verification failed: signature and/or required key missing - tainting kernel Mar 18 01:37:38 longsky-ThinkPad-T440 kernel: [ 0.124190] ACPI Error: Method parse/execution failed \_PR.CPU0._PDC, AE_AML_OPERAND_TYPE (20170531/psparse-550) Mar 18 01:37:38 longsky-ThinkPad-T440 kernel: [ 0.152056] acpi PNP0A08:00: _OSC failed (AE_SUPPORT); disabling ASPM Mar 18 01:37:38 longsky-ThinkPad-T440 kernel: [ 0.237589] pci 0000:04:00.0: BAR 6: failed to assign [mem size 0x00080000 pref] Mar 18 01:37:38 longsky-ThinkPad-T440 kernel: [ 6.434639] nvidia: module verification failed: signature and/or required key missing - tainting kernel Mar 17 19:29:53 longsky-ThinkPad-T440 kernel: [ 6740.713268] wlan0: failed to remove key (1, ff:ff:ff:ff:ff:ff) from hardware (-22) Mar 17 19:29:53 longsky-ThinkPad-T440 kernel: [ 6740.713419] wlan0: failed to remove key (2, ff:ff:ff:ff:ff:ff) from hardware (-22)
这种情况是更新到最新的Linux-4.13.0-37内核，并且安装NVIDIA 340.14版本的闭源显卡驱动导致的。早期版本的的开源驱动会无法进入桌面，因此才安装的闭源显卡驱动。没有想到内核更新之后，会导致闭源驱动出现异常。
修复方法是切换到开源驱动即可：
