Public bug reported:

Summary
The graphical disk-unlock prompt appears during boot and lets me start entering 
my password. The screen then refreshes and wipes the password input I have 
already typed, forcing me to re-enter it. This is not merely a cosmetic black 
flash: accepted password-entry progress is lost.

System
- Ubuntu 26.04.1 LTS (resolute), amd64
- MSI Stealth GS66 12UGS / MS-16V5
- Encrypted root with device-mapper crypt and LVM
- Kernel: 7.0.0-38-generic; Ubuntu version signature 7.0.0-38.38-generic 7.0.14
- plymouth: 24.004.60+git20250831.4a3c171d-0ubuntu8
- dracut/dracut-core: 110-11ubuntu0.1; initramfs-tools is not installed
- systemd/systemd-cryptsetup/udev: 259.9-0ubuntu0.1
- Intel Alder Lake-P Iris Xe, PCI ID 8086:46a6, using i915
- NVIDIA RTX 3070 Ti Laptop GPU, PCI ID 10de:24a0; NVIDIA open driver 595.99.02
- Normal graphical boot uses quiet splash.

Steps to reproduce the reported behavior
1. Boot the machine normally with the graphical encrypted-disk unlock prompt 
enabled.
2. As soon as the unlock prompt appears, begin typing the disk passphrase.
3. The screen refreshes during entry and clears the input that has already been 
entered.

Expected
Once the prompt is visible and accepts input, password-entry state remains 
intact across redraws/display-driver handoffs. The user should not have to wait 
for an unpredictable refresh before starting to type.

Actual / impact
The prompt accepts initial password input, then a refresh wipes it and the user 
has to start again. This is an annoying interruption to boot and password 
entry. It is not an assertion that the passphrase is wrong or that encryption 
fails. Exact recurrence rate, a video of the refresh, and whether every 
individual keystroke is discarded have not been independently measured. The 
input-clearing behavior is the user's direct observation; the diagnostic 
investigation did not reboot the machine to reproduce it.

Current boot evidence (kernel-relative timestamps)
[1.049700] simpledrm initialized for the firmware framebuffer.
[1.049766] simple-framebuffer: fb0: simpledrmdrmfb frame buffer device
[1.777211] [nvidia-drm] Loading driver
[3.543122] nvidia-drm initialized
[3.544093] nvidia: [drm] Cannot find any crtc or sizes
[19.454943] i915: Found alderlake_p integrated display
[19.492046] i915: vgaarb: deactivate vga console
[19.525352] i915 initialized
[19.584011] fbcon: i915drmfb (fb0) is primary device
[19.584082] i915: [drm] fb0: i915drmfb frame buffer device
[19.677289] i915: [drm] *ERROR* CPU pipe A FIFO underrun

Initrd systemd records cryptsetup completing around 16.78 seconds and
switching root around 17.64 seconds. The boot subsequently reaches GDM
and the graphical target. The i915 FIFO-underrun message also appears in
the preceding boot on the same kernel.

Hypothesis, not established cause
The late simpledrm-to-i915 framebuffer/mode handoff is a plausible trigger for 
the refresh. The retained logs cannot show the actual screen or prove that this 
event clears Plymouth's input. The active initrd could not be listed without 
administrator authentication, so whether i915 is absent from the initrd or 
simply initializes late is unverified.

Related report, not a confirmed duplicate
https://bugs.launchpad.net/bugs/2092649 concerns passphrase entry and late 
graphics-driver initialization on older Ubuntu/kernel versions. This report 
specifically concerns input being accepted and then cleared by a refresh on 
Ubuntu 26.04 with kernel 7.0.0-38, rather than assuming the same cause or total 
keyboard unresponsiveness.

Initial component selection
Filed against plymouth because the visible password-entry state is lost during 
a boot-screen refresh. Please reassign or add linux/dracut tasks if early 
KMS/module inclusion is the cause. This issue is intentionally separate from 
the late shutdown hang requiring forced power-off; no common cause has been 
established. No disk passphrase, password contents, or encryption key material 
is included.

Separate report from this investigation (no shared cause established):
https://bugs.launchpad.net/bugs/2172253

** Affects: plymouth (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 resolute

** Description changed:

  Summary
  The graphical disk-unlock prompt appears during boot and lets me start 
entering my password. The screen then refreshes and wipes the password input I 
have already typed, forcing me to re-enter it. This is not merely a cosmetic 
black flash: accepted password-entry progress is lost.
  
  System
  - Ubuntu 26.04.1 LTS (resolute), amd64
  - MSI Stealth GS66 12UGS / MS-16V5
  - Encrypted root with device-mapper crypt and LVM
  - Kernel: 7.0.0-38-generic; Ubuntu version signature 7.0.0-38.38-generic 
7.0.14
  - plymouth: 24.004.60+git20250831.4a3c171d-0ubuntu8
  - dracut/dracut-core: 110-11ubuntu0.1; initramfs-tools is not installed
  - systemd/systemd-cryptsetup/udev: 259.9-0ubuntu0.1
  - Intel Alder Lake-P Iris Xe, PCI ID 8086:46a6, using i915
  - NVIDIA RTX 3070 Ti Laptop GPU, PCI ID 10de:24a0; NVIDIA open driver 
595.99.02
  - Normal graphical boot uses quiet splash.
  
  Steps to reproduce the reported behavior
  1. Boot the machine normally with the graphical encrypted-disk unlock prompt 
enabled.
  2. As soon as the unlock prompt appears, begin typing the disk passphrase.
  3. The screen refreshes during entry and clears the input that has already 
been entered.
  
  Expected
  Once the prompt is visible and accepts input, password-entry state remains 
intact across redraws/display-driver handoffs. The user should not have to wait 
for an unpredictable refresh before starting to type.
  
  Actual / impact
  The prompt accepts initial password input, then a refresh wipes it and the 
user has to start again. This is an annoying interruption to boot and password 
entry. It is not an assertion that the passphrase is wrong or that encryption 
fails. Exact recurrence rate, a video of the refresh, and whether every 
individual keystroke is discarded have not been independently measured. The 
input-clearing behavior is the user's direct observation; the diagnostic 
investigation did not reboot the machine to reproduce it.
  
  Current boot evidence (kernel-relative timestamps)
  [1.049700] simpledrm initialized for the firmware framebuffer.
  [1.049766] simple-framebuffer: fb0: simpledrmdrmfb frame buffer device
  [1.777211] [nvidia-drm] Loading driver
  [3.543122] nvidia-drm initialized
  [3.544093] nvidia: [drm] Cannot find any crtc or sizes
  [19.454943] i915: Found alderlake_p integrated display
  [19.492046] i915: vgaarb: deactivate vga console
  [19.525352] i915 initialized
  [19.584011] fbcon: i915drmfb (fb0) is primary device
  [19.584082] i915: [drm] fb0: i915drmfb frame buffer device
  [19.677289] i915: [drm] *ERROR* CPU pipe A FIFO underrun
  
  Initrd systemd records cryptsetup completing around 16.78 seconds and
  switching root around 17.64 seconds. The boot subsequently reaches GDM
  and the graphical target. The i915 FIFO-underrun message also appears in
  the preceding boot on the same kernel.
  
  Hypothesis, not established cause
  The late simpledrm-to-i915 framebuffer/mode handoff is a plausible trigger 
for the refresh. The retained logs cannot show the actual screen or prove that 
this event clears Plymouth's input. The active initrd could not be listed 
without administrator authentication, so whether i915 is absent from the initrd 
or simply initializes late is unverified.
  
  Related report, not a confirmed duplicate
  https://bugs.launchpad.net/bugs/2092649 concerns passphrase entry and late 
graphics-driver initialization on older Ubuntu/kernel versions. This report 
specifically concerns input being accepted and then cleared by a refresh on 
Ubuntu 26.04 with kernel 7.0.0-38, rather than assuming the same cause or total 
keyboard unresponsiveness.
  
  Initial component selection
  Filed against plymouth because the visible password-entry state is lost 
during a boot-screen refresh. Please reassign or add linux/dracut tasks if 
early KMS/module inclusion is the cause. This issue is intentionally separate 
from the late shutdown hang requiring forced power-off; no common cause has 
been established. No disk passphrase, password contents, or encryption key 
material is included.
+ 
+ Separate report from this investigation (no shared cause established):
+ https://bugs.launchpad.net/bugs/2172253

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https://bugs.launchpad.net/bugs/2172254

Title:
  Disk-unlock prompt accepts password input then refreshes and clears it
  during boot

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