Public bug reported:
Intermittent cold-boot hang (blank screen, blinking cursor top-left,
immediately after GRUB handoff, before any kernel/userspace logging
begins) on ThinkPad T14s Gen 4, AMD Ryzen 7 PRO 7840U / Radeon 780M
(Phoenix, gfx1103). Occurs roughly once every 4-11 cold boots. Never
reproducible on warm reboots. Requires hard power-off.
Controlled test confirms amdgpu.runpm=0 is necessary but not sufficient:
removing it (keeping all other parameters) reproduced the hang on the
very next cold boot; re-adding it plus amdgpu.dcdebugmask=0x10 has not
eliminated recurrence.
Related bugs (not exact duplicates)
Bug #2141725 — same Phoenix/gfx1103 family, same runpm=0 workaround, but that
case is deterministic and fully resolved by the parameter alone. This case is
intermittent even with it active.
Bug #2147367 — same gfx1103 silicon, intermittent pattern, but triggered
hours into a GPU-loaded session, not at cold boot, on different
hardware/kernel.
System
Lenovo ThinkPad T14s Gen 4, Type 21F9CTO1WW
AMD Ryzen 7 PRO 7840U / Radeon 780M (gfx1103_r1)
BIOS R2EET49W (1.30) — no newer version listed by Lenovo for this model
Ubuntu 22.04.5 LTS, kernel 6.8.0-138-generic (confirmed ceiling for
22.04, no 6.11+ available via HWE/OEM)
linux-firmware 20220329.git681281e4-0ubuntu3.42
Samsung MZVL21T0HDLU-00BLL NVMe, firmware 6L2QGXD7
Current kernel command line
quiet nvme_core.default_ps_max_latency_us=5500 amdgpu.runpm=0
amdgpu.dcdebugmask=0x10 usbcore.autosuspend=-1 i8042.nomux=1 i8042.reset
i2c_hid.polling_mode=1
Steps already tried, none fully resolved
BIOS 0.1.24 -> 0.1.30
nvme_core.default_ps_max_latency_us=5500
GRUB_TERMINAL=console (ruled out, reverted)
amdgpu.runpm=0 (necessary, confirmed via removal test, but insufficient
alone)
amdgpu.dcdebugmask=0x10 added alongside runpm=0
Log evidence
journalctl and Xorg.0.log show no anomalies on any boot following a hang — the
failed boot itself never produces a boot ID or journal entries, confirming the
freeze occurs before systemd-journald starts.
Request
Is this a distinct manifestation of the same Phoenix/gfx1103 instability as
#2141725/#2147367, or separate? Also requesting guidance on capturing evidence
before journald starts (pstore/earlycon/netconsole), since journalctl
structurally cannot see this freeze window.
ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: linux-image-6.8.0-138-generic 6.8.0-138.138~22.04.1
ProcVersionSignature: Ubuntu 6.8.0-138.138~22.04.1-generic 6.8.12
Uname: Linux 6.8.0-138-generic x86_64
ApportVersion: 2.20.11-0ubuntu82.10
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC2: ram 1103 F.... pulseaudio
/dev/snd/controlC1: ram 1103 F.... pulseaudio
/dev/snd/controlC0: ram 1103 F.... pulseaudio
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: XFCE
Date: Wed Aug 26 10:07:20 2026
InstallationDate: Installed on 2025-05-14 (468 days ago)
InstallationMedia: Xubuntu 22.04.5 LTS "Jammy Jellyfish" - Release amd64
(20240911)
MachineType: LENOVO 21F9CTO1WW
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-138-generic
root=UUID=0852e4d0-0efa-47ce-bec0-3c1fdabc7f8a ro quiet
nvme_core.default_ps_max_latency_us=5500 amdgpu.dcdebugmask=0x10
usbcore.autosuspend=-1 i8042.nomux=1 i8042.reset
RelatedPackageVersions:
linux-restricted-modules-6.8.0-138-generic N/A
linux-backports-modules-6.8.0-138-generic N/A
linux-firmware 20220329.git681281e4-0ubuntu3.42
SourcePackage: linux-hwe-6.8
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/18/2026
dmi.bios.release: 1.30
dmi.bios.vendor: LENOVO
dmi.bios.version: R2EET49W (1.30 )
dmi.board.asset.tag: Not Available
dmi.board.name: 21F9CTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.19
dmi.modalias:
dmi:bvnLENOVO:bvrR2EET49W(1.30):bd03/18/2026:br1.30:efr1.19:svnLENOVO:pn21F9CTO1WW:pvrThinkPadT14sGen4:rvnLENOVO:rn21F9CTO1WW:rvrNotDefined:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_21F9_BU_Think_FM_ThinkPadT14sGen4:
dmi.product.family: ThinkPad T14s Gen 4
dmi.product.name: 21F9CTO1WW
dmi.product.sku: LENOVO_MT_21F9_BU_Think_FM_ThinkPad T14s Gen 4
dmi.product.version: ThinkPad T14s Gen 4
dmi.sys.vendor: LENOVO
** Affects: linux-hwe-6.8 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug jammy
** Attachment added: "Xorg.0.log"
https://bugs.launchpad.net/bugs/2165096/+attachment/5995370/+files/Xorg.0.log
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https://bugs.launchpad.net/bugs/2165096
Title:
Intermittent cold-boot hang before kernel logging on ThinkPad T14s Gen
4 (AMD Phoenix/Radeon 780M), persists with amdgpu.runpm=0
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