[这个问题我认为是重复的这里但我认为值得提供另一个更详细的信息）]
我正在尝试为我的笔记本电脑（Lenovo Thinkpad L380）设置外接显示器，但未检测到 HDMI 端口（笔记本电脑上只有一个）。我有一个双启动系统，相同的显示器+HDMI 设置在 Windows 发行版上工作正常，但在 Ubuntu 上却不行。- Settings>Displays部分没有显示多个显示器，结果发现根本xrandr没有检测到 HDMI 端口。我尝试检查可用的驱动程序更新，更改显示管理器（在gdm3和之间，lightdm如建议的那样这里），但无济于事，HDMI 端口没有显示xrandr：
$ xrandr --query
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected primary 1920x1080+0+0 0mm x 0mm
1920x1080 77.00*
也不使用aplay：
$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC257 Analog [ALC257 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
我的笔记本电脑使用如下所示的默认英特尔显卡：
$ sudo lshw -c video
*-display UNCLAIMED
description: VGA compatible controller
product: UHD Graphics 620
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
version: 07
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm vga_controller bus_master cap_list
configuration: latency=0
resources: memory:f0000000-f0ffffff memory:e0000000-efffffff ioport:e000(size=64) memory:c0000-dffff
以下是我的xorg.conf文件：
Section "Device"
Identifier "Intel"
Driver "intel"
# Option "AccelMethod" "uxa"
EndSection
xrandr为了提供更多信息（以防万一），以下是详细程度设置的输出：
$ xrandr --verbose
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected primary 1920x1080+0+0 (0x528) normal (normal) 0mm x 0mm
Identifier: 0x527
Timestamp: 12935
Subpixel: unknown
Clones:
CRTC: 0
CRTCs: 0
Transform: 1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
0.000000 0.000000 1.000000
filter:
_MUTTER_PRESENTATION_OUTPUT: 0
non-desktop: 0
supported: 0, 1
1920x1080 (0x528) 159.667MHz *current
h: width 1920 start 0 end 0 total 1920 skew 0 clock 83.16KHz
v: height 1080 start 0 end 0 total 1080 clock 77.00Hz
以及sudo lspci -vnn与VGA控制器相关的输出：
00:02.0 VGA compatible controller [0300]: Intel Corporation UHD Graphics 620 [8086:5917] (rev 07) (prog-if 00 [VGA controller])
Subsystem: Lenovo UHD Graphics 620 [17aa:506c]
Flags: bus master, fast devsel, latency 0, IRQ 255
Memory at f0000000 (64-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
I/O ports at e000 [disabled] [size=64]
Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
Capabilities: [40] Vendor Specific Information: Len=0c <?>
Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [ac] MSI: Enable- Count=1/1 Maskable- 64bit-
Capabilities: [d0] Power Management version 2
Capabilities: [100] Process Address Space ID (PASID)
Capabilities: [200] Address Translation Service (ATS)
Capabilities: [300] Page Request Interface (PRI)
Kernel modules: i915
我想也许 I/O 端口被禁用可能与我的问题有关？