Public bug reported:
The Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0) does not reliably
enumerate all PCIe devices during a cold boot when it is connected
before powering on the system.
USB devices are usually detected correctly, and the dock's USB audio
device is available. However, the Ethernet adapter and DisplayPort-
connected external monitors frequently fail to appear.
The issue is fully reproducible.
If the system is booted without the dock attached and the dock is
connected after logging into KDE Plasma, all dock functions (USB,
Ethernet, audio and external displays) work correctly every time without
requiring a reboot.
Hardware
Laptop: Lenovo ThinkPad T14 Gen 6 Intel
Dock: Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0)
BIOS: N4JET27W (Version 1.17, 2026-05-22)
Distribution: Kubuntu 24.04 LTS
Kernel: 6.17.0-35-generic
Steps to reproduce
Shut down the laptop.
Connect the Thunderbolt dock.
Power on the laptop.
Boot into Kubuntu.
Expected result:
All dock devices should be available immediately after boot:
USB devices
Ethernet adapter
Audio device
External DisplayPort monitors
Actual result
During a cold boot with the dock already connected:
USB devices are detected.
Dock audio is available.
Ethernet frequently does not appear.
External monitors are frequently not detected.
Boot time is significantly longer than when booting without the dock attached.
External displays frequently not connected.
If the dock is disconnected and connected again after the user has
logged into KDE Plasma, all devices immediately become available and
work correctly.
Additional observations:
Thunderbolt itself appears to initialize successfully.
boltctl reports the dock as:
Authorized
USB4
40 Gb/s RX
40 Gb/s TX
Kernel logs contain repeated PCI bridge resource allocation messages
during boot (for example, "bridge window ... failed to assign").
The issue only occurs when the dock is connected before boot.
Booting without the dock attached and connecting it after login works
reliably every time.
Additional information
This does not appear to be a hardware problem because:
Windows 11 on the same hardware works correctly with the same dock.
The same Linux kernel detects and initializes all dock devices correctly when
the dock is connected after the operating system has finished booting.
Thank you for your time.
Kind regards,
Sebastian
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-35-generic 6.17.0-35.35~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-35-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: basti 2480 F.... wireplumber
/dev/snd/controlC0: basti 2477 F.... pipewire
basti 2480 F.... wireplumber
/dev/snd/seq: basti 2477 F.... pipewire
CasperMD5CheckResult: unknown
Date: Sun Jun 28 11:02:29 2026
InstallationDate: Installed on 2026-06-21 (7 days ago)
InstallationMedia: Kubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: LENOVO 21QCCTO1WW
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-35-generic
root=UUID=9bf6ed38-f4b6-4140-83ab-be13f772ea14 ro quiet
cryptdevice=UUID=d32693dd-b7bf-4a93-972f-9d8d64a877ce:luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce
root=/dev/mapper/luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.17.0-35-generic N/A
linux-backports-modules-6.17.0-35-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/22/2026
dmi.bios.release: 1.17
dmi.bios.vendor: LENOVO
dmi.bios.version: N4JET27W (1.17 )
dmi.board.asset.tag: Not Available
dmi.board.name: 21QCCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76530 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.12
dmi.modalias:
dmi:bvnLENOVO:bvrN4JET27W(1.17):bd05/22/2026:br1.17:efr1.12:svnLENOVO:pn21QCCTO1WW:pvrThinkPadT14Gen6:rvnLENOVO:rn21QCCTO1WW:rvrSDK0T76530WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21QC_BU_Think_FM_ThinkPadT14Gen6:
dmi.product.family: ThinkPad T14 Gen 6
dmi.product.name: 21QCCTO1WW
dmi.product.sku: LENOVO_MT_21QC_BU_Think_FM_ThinkPad T14 Gen 6
dmi.product.version: ThinkPad T14 Gen 6
dmi.sys.vendor: LENOVO
** Affects: linux-hwe-6.17 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
** Attachment added: "boltctl_lsusb.txt"
https://bugs.launchpad.net/bugs/2158560/+attachment/5979327/+files/boltctl_lsusb.txt
** Description changed:
The Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0) does not reliably
enumerate all PCIe devices during a cold boot when it is connected
before powering on the system.
USB devices are usually detected correctly, and the dock's USB audio
device is available. However, the Ethernet adapter and DisplayPort-
connected external monitors frequently fail to appear.
The issue is fully reproducible.
If the system is booted without the dock attached and the dock is
connected after logging into KDE Plasma, all dock functions (USB,
Ethernet, audio and external displays) work correctly every time without
requiring a reboot.
Hardware
Laptop: Lenovo ThinkPad T14 Gen 6 Intel
Dock: Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0)
BIOS: N4JET27W (Version 1.17, 2026-05-22)
+
Distribution: Kubuntu 24.04 LTS
Kernel: 6.17.0-35-generic
+
Steps to reproduce
Shut down the laptop.
Connect the Thunderbolt dock.
Power on the laptop.
Boot into Kubuntu.
Observe the available dock devices.
Expected result
All dock devices should be available immediately after boot:
USB devices
Ethernet adapter
Audio device
External DisplayPort monitors
Actual result
During a cold boot with the dock already connected:
USB devices are detected.
Dock audio is available.
Ethernet frequently does not appear.
External monitors are frequently not detected.
Boot time is significantly longer than when booting without the dock attached.
Externel displays frequently not connected.
If the dock is disconnected and connected again after the user has
logged into KDE Plasma, all devices immediately become available and
work correctly.
Additional observations
Thunderbolt itself appears to initialize successfully.
boltctl reports the dock as:
Authorized
USB4
40 Gb/s RX
40 Gb/s TX
The attached kernel logs contain repeated PCI bridge resource allocation
messages during boot (for example, "bridge window ... failed to
assign"). The complete logs collected by ubuntu-bug linux are attached
to this report.
The issue only occurs when the dock is connected before boot.
Booting without the dock attached and connecting it after login works
reliably every time.
Additional information
This does not appear to be a hardware problem because:
Windows 11 on the same hardware works correctly with the same dock.
The same Linux kernel detects and initializes all dock devices correctly when
the dock is connected after the operating system has finished booting.
Based on the observed behavior, this appears to be related to device
enumeration during early boot rather than a hardware failure.
Thank you for your time.
Kind regards,
Sebastian
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-35-generic 6.17.0-35.35~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-35-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
- USER PID ACCESS COMMAND
- /dev/snd/controlC1: basti 2480 F.... wireplumber
- /dev/snd/controlC0: basti 2477 F.... pipewire
- basti 2480 F.... wireplumber
- /dev/snd/seq: basti 2477 F.... pipewire
+ USER PID ACCESS COMMAND
+ /dev/snd/controlC1: basti 2480 F.... wireplumber
+ /dev/snd/controlC0: basti 2477 F.... pipewire
+ basti 2480 F.... wireplumber
+ /dev/snd/seq: basti 2477 F.... pipewire
CasperMD5CheckResult: unknown
Date: Sun Jun 28 11:02:29 2026
InstallationDate: Installed on 2026-06-21 (7 days ago)
InstallationMedia: Kubuntu 24.04.4 LTS "Noble Numbat" - Release amd64
(20260210)
MachineType: LENOVO 21QCCTO1WW
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-35-generic
root=UUID=9bf6ed38-f4b6-4140-83ab-be13f772ea14 ro quiet
cryptdevice=UUID=d32693dd-b7bf-4a93-972f-9d8d64a877ce:luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce
root=/dev/mapper/luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce splash vt.handoff=7
RelatedPackageVersions:
- linux-restricted-modules-6.17.0-35-generic N/A
- linux-backports-modules-6.17.0-35-generic N/A
- linux-firmware 20240318.git3b128b60-0ubuntu2.27
+ linux-restricted-modules-6.17.0-35-generic N/A
+ linux-backports-modules-6.17.0-35-generic N/A
+ linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/22/2026
dmi.bios.release: 1.17
dmi.bios.vendor: LENOVO
dmi.bios.version: N4JET27W (1.17 )
dmi.board.asset.tag: Not Available
dmi.board.name: 21QCCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76530 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.12
dmi.modalias:
dmi:bvnLENOVO:bvrN4JET27W(1.17):bd05/22/2026:br1.17:efr1.12:svnLENOVO:pn21QCCTO1WW:pvrThinkPadT14Gen6:rvnLENOVO:rn21QCCTO1WW:rvrSDK0T76530WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21QC_BU_Think_FM_ThinkPadT14Gen6:
dmi.product.family: ThinkPad T14 Gen 6
dmi.product.name: 21QCCTO1WW
dmi.product.sku: LENOVO_MT_21QC_BU_Think_FM_ThinkPad T14 Gen 6
dmi.product.version: ThinkPad T14 Gen 6
dmi.sys.vendor: LENOVO
** Description changed:
The Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0) does not reliably
enumerate all PCIe devices during a cold boot when it is connected
before powering on the system.
USB devices are usually detected correctly, and the dock's USB audio
device is available. However, the Ethernet adapter and DisplayPort-
connected external monitors frequently fail to appear.
The issue is fully reproducible.
If the system is booted without the dock attached and the dock is
connected after logging into KDE Plasma, all dock functions (USB,
Ethernet, audio and external displays) work correctly every time without
requiring a reboot.
Hardware
Laptop: Lenovo ThinkPad T14 Gen 6 Intel
Dock: Lenovo ThinkPad Thunderbolt 4 Dock (Type 40B0)
BIOS: N4JET27W (Version 1.17, 2026-05-22)
Distribution: Kubuntu 24.04 LTS
Kernel: 6.17.0-35-generic
Steps to reproduce
Shut down the laptop.
Connect the Thunderbolt dock.
Power on the laptop.
Boot into Kubuntu.
- Observe the available dock devices.
- Expected result
+
+ Expected result:
All dock devices should be available immediately after boot:
USB devices
Ethernet adapter
Audio device
External DisplayPort monitors
Actual result
During a cold boot with the dock already connected:
USB devices are detected.
Dock audio is available.
Ethernet frequently does not appear.
External monitors are frequently not detected.
Boot time is significantly longer than when booting without the dock attached.
- Externel displays frequently not connected.
+ External displays frequently not connected.
If the dock is disconnected and connected again after the user has
logged into KDE Plasma, all devices immediately become available and
work correctly.
- Additional observations
+ Additional observations:
Thunderbolt itself appears to initialize successfully.
boltctl reports the dock as:
Authorized
USB4
40 Gb/s RX
40 Gb/s TX
- The attached kernel logs contain repeated PCI bridge resource allocation
- messages during boot (for example, "bridge window ... failed to
- assign"). The complete logs collected by ubuntu-bug linux are attached
- to this report.
+ Kernel logs contain repeated PCI bridge resource allocation messages
+ during boot (for example, "bridge window ... failed to assign").
The issue only occurs when the dock is connected before boot.
Booting without the dock attached and connecting it after login works
reliably every time.
Additional information
This does not appear to be a hardware problem because:
Windows 11 on the same hardware works correctly with the same dock.
The same Linux kernel detects and initializes all dock devices correctly when
the dock is connected after the operating system has finished booting.
-
- Based on the observed behavior, this appears to be related to device
- enumeration during early boot rather than a hardware failure.
Thank you for your time.
Kind regards,
Sebastian
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.17.0-35-generic 6.17.0-35.35~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-35.35~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-35-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: basti 2480 F.... wireplumber
/dev/snd/controlC0: basti 2477 F.... pipewire
basti 2480 F.... wireplumber
/dev/snd/seq: basti 2477 F.... pipewire
CasperMD5CheckResult: unknown
Date: Sun Jun 28 11:02:29 2026
InstallationDate: Installed on 2026-06-21 (7 days ago)
InstallationMedia: Kubuntu 24.04.4 LTS "Noble Numbat" - Release amd64
(20260210)
MachineType: LENOVO 21QCCTO1WW
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-6.17.0-35-generic
root=UUID=9bf6ed38-f4b6-4140-83ab-be13f772ea14 ro quiet
cryptdevice=UUID=d32693dd-b7bf-4a93-972f-9d8d64a877ce:luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce
root=/dev/mapper/luks-d32693dd-b7bf-4a93-972f-9d8d64a877ce splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.17.0-35-generic N/A
linux-backports-modules-6.17.0-35-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-6.17
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/22/2026
dmi.bios.release: 1.17
dmi.bios.vendor: LENOVO
dmi.bios.version: N4JET27W (1.17 )
dmi.board.asset.tag: Not Available
dmi.board.name: 21QCCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76530 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.12
dmi.modalias:
dmi:bvnLENOVO:bvrN4JET27W(1.17):bd05/22/2026:br1.17:efr1.12:svnLENOVO:pn21QCCTO1WW:pvrThinkPadT14Gen6:rvnLENOVO:rn21QCCTO1WW:rvrSDK0T76530WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21QC_BU_Think_FM_ThinkPadT14Gen6:
dmi.product.family: ThinkPad T14 Gen 6
dmi.product.name: 21QCCTO1WW
dmi.product.sku: LENOVO_MT_21QC_BU_Think_FM_ThinkPad T14 Gen 6
dmi.product.version: ThinkPad T14 Gen 6
dmi.sys.vendor: LENOVO
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2158560
Title:
Lenovo Thunderbolt 4 Dock (40B0) intermittently fails to enumerate
PCIe devices during cold boot on Lenovo ThinkPad T14 Gen 6 Intel
(USB4/Thunderbolt works after hotplug)
To manage notifications about this bug go to:
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