Public bug reported:
== Summary ==
On roughly 20% of power-ons, the laptop boots to a black screen: the panel
stays dark while the system continues running normally (keyboard backlight
on, services start, journal logs normally). Failed boots are accompanied by
a flood of amdgpu DMUB/DMCUB errors. A subsequent reboot always succeeds.
== System ==
- Ubuntu 26.04.1 LTS (resolute), all updates
- Kernel: 7.0.0-38-generic #38-Ubuntu SMP PREEMPT_DYNAMIC
- Desktop: KDE Plasma 6.6.6, Wayland (SDDM)
- Hardware: Lenovo IdeaPad Slim 3 15AHP10 (83KA), BIOS QACN26WW (10/20/2025)
- GPU: AMD HawkPoint1 [1002:1900] (rev c2), driver amdgpu
- linux-firmware-amd-graphics 20260319.git217ca6e4-0ubuntu3.1
- DMUB firmware: version=0x08005700 (loaded via PSP)
- Kernel cmdline: quiet splash (no amdgpu-specific parameters)
== Steps to reproduce ==
1. Power the laptop off completely.
2. Power it on (cold boot).
3. In roughly 1 of 5 attempts the screen stays black after splash; the
system itself boots fine (verifiable via logs).
== Expected ==
Panel (eDP-1) initializes and the SDDM greeter appears on every boot.
== Actual ==
Black screen. The journal shows the boot proceeding normally, but SDDM/KWin
fails to bring up the display, alongside repeated:
amdgpu 0000:04:00.0: [drm] *ERROR* Error queueing DMUB command: status=2
amdgpu 0000:04:00.0: [drm] *ERROR* dc_dmub_srv_log_diagnostic_data: DMCUB
error - collecting diagnostic data
kwin_wayland_drm: atomic commit failed: Device or resource busy
workqueue: dm_handle_vmin_vmax_update [amdgpu] hogged CPU for >10000us
== Frequency (journalctl statistics, last 46 boots) ==
9 of 46 boots show the DMCUB error flood; almost all of them cold boots.
Example sequence on 2026-10-07 (CEST):
08:40:47 boot #1: 220 DMCUB errors, no display -> power-cycled
08:42:38 boot #2: 90 DMCUB errors, no display -> power-cycled
08:43:29 boot #3: 90 DMCUB errors, no display -> power-cycled
08:44:32 boot #4: 0 DMCUB errors, boots fine
A warm reboot after a failed attempt virtually always succeeds; the errors
repeat every ~1 s during the failed ~30 s boot.
== Notes ==
- Not related to suspend/resume (one suspend cycle in 14 days).
- Not correlated with package/kernel changes (same kernel and firmware in
all affected boots; intermittent for months).
- Similar reports: Lenovo IdeaPad + mainline 7.0 kernel with dpcd/DMUB
errors and black screen (CachyOS forum, Apr 2026); Launchpad #2144530
(amdgpu DC/DMUB regression, different hardware).
- Workaround `amdgpu.dcdebugmask=0x10` (disable PSR) is known for this
symptom class but NOT yet tested here.
- Full journalctl output of failed and successful boots available on request.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-38-generic 7.0.0-38.38
ProcVersionSignature: Ubuntu 7.0.0-38.38-generic 7.0.14
Uname: Linux 7.0.0-38-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: KDE
CurrentDmesg: Error: command ['pkexec', 'dmesg'] failed with exit code 127:
pkexec must be setuid root
Date: Wed Oct 7 09:54:31 2026
InstallationDate: Installed on 2026-06-11 (118 days ago)
InstallationMedia: Kubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423)
MachineType: LENOVO 83KA
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-38-generic
root=UUID=6c69ad4e-ec71-4205-9946-0bfb2532d27e ro quiet splash
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
acpidump: Error: command ['pkexec', '/usr/share/apport/dump_acpi_tables.py']
failed with exit code 127: pkexec must be setuid root
dmi.bios.date: 10/20/2025
dmi.bios.release: 1.26
dmi.bios.vendor: LENOVO
dmi.bios.version: QACN26WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0T76463WIN
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: IdeaPad Slim 3 15AHP10
dmi.ec.firmware.release: 1.23
dmi.modalias:
dmi:bvnLENOVO:bvrQACN26WW:bd10/20/2025:br1.26:efr1.23:svnLENOVO:pn83KA:pvrIdeaPadSlim315AHP10:rvnLENOVO:rnLNVNB161216:rvrSDK0T76463WIN:cvnLENOVO:ct10:cvrIdeaPadSlim315AHP10:skuLENOVO_MT_83KA_BU_idea_FM_IdeaPadSlim315AHP10:pfaIdeaPadSlim315AHP10:
dmi.product.family: IdeaPad Slim 3 15AHP10
dmi.product.name: 83KA
dmi.product.sku: LENOVO_MT_83KA_BU_idea_FM_IdeaPad Slim 3 15AHP10
dmi.product.version: IdeaPad Slim 3 15AHP10
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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https://bugs.launchpad.net/bugs/2169805
Title:
[7.0.0-38] amdgpu: DMUB/DMCUB errors + intermittent black screen on
boot on Lenovo IdeaPad Slim 3 15AHP10 (HawkPoint1 1002:1900)
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