Host OS display setup (panel-as-monitor)

Summary

CASEDD’s small in-case panel is physically mounted rotated, and it is also used as a real Linux console/monitor (local login prompt, getty) outside of CASEDD’s own rendering. Two host-level (kernel) settings are required so the OS-level output — not just CASEDD’s own frames — displays correctly:

  1. Rotate the kernel framebuffer console 180° so the text-mode login prompt (and any other kernel console output) renders right-side up on the physically-rotated panel.
  2. Disable the blinking VT cursor globally so the login prompt’s cursor doesn’t blink on top of the panel when no getty is actively focused, independent of CASEDD’s own per-session cursor suppression (see deploy/casedd.service, which hides the cursor only while CASEDD itself is running).

These are host OS settings — they must be reapplied after a fresh OS install/reimage. They are not part of deploy/install/install.sh because they touch the bootloader and require a reboot; apply them once per machine.

Why this is separate from CASEDD’s own rotation

casedd.yaml’s fb_rotation (or CASEDD_FB_ROTATION) only rotates the frames CASEDD itself writes via direct framebuffer mmap. It has no effect on the kernel’s own text console (login prompt, dmesg, systemd boot messages) because CASEDD writes raw pixels straight to the framebuffer, bypassing the kernel’s fbcon text renderer entirely. If the panel is mounted upside-down (or rotated any other way), the kernel console must be rotated independently at the OS level using the settings below.

Applying the fix

Edit /etc/default/grub and set (adjust the rotate value for your panel’s physical orientation — see Rotation values below):

sudo sed -i \
  's|^GRUB_CMDLINE_LINUX_DEFAULT=.*|GRUB_CMDLINE_LINUX_DEFAULT="fbcon=rotate:2 vt.global_cursor_default=0"|' \
  /etc/default/grub
sudo update-grub
sudo reboot
  • fbcon=rotate:2 — rotates the kernel framebuffer console 180°. This is what makes the local login prompt (and any other kernel-console text) display right-side up on a panel mounted upside-down.
  • vt.global_cursor_default=0 — disables the blinking text-mode cursor on all virtual terminals by default at boot. This complements (does not replace) deploy/casedd.service’s ExecStartPre cursor-blink toggle, which only takes effect while the CASEDD service itself is active.

Rotation values

fbcon=rotate:N accepts:

N Rotation
0 Normal (no rotation)
1 90° clockwise
2 180° (upside-down panel)
3 270° clockwise (90° counter-clockwise)

This should normally match the same physical orientation used for fb_rotation / CASEDD_FB_ROTATION in casedd.yaml, since both the kernel console and CASEDD’s own frames are being displayed on the same physically-mounted panel.

Testing without rebooting

Both settings have live sysfs equivalents under /sys/class/graphics/fbcon/ that take effect immediately (useful for testing the correct rotation value before persisting it via GRUB and rebooting):

# Rotate console output live (0-3, see table above)
echo 2 | sudo tee /sys/class/graphics/fbcon/rotate
# Apply the same rotation to every allocated console, not just the active one
echo 2 | sudo tee /sys/class/graphics/fbcon/rotate_all
# Disable the blinking cursor live
echo 0 | sudo tee /sys/class/graphics/fbcon/cursor_blink

These sysfs writes do not persist across reboots — always follow up with the GRUB change above once you’ve confirmed the correct rotation value.

  • deploy/casedd.service — disables the blink cursor while CASEDD itself is the active console/service (separate from the OS-wide default above).
  • docs/INPUTLESS_MONITOR.md — CASEDD’s own framebuffer claim/unblank behavior when no local keyboard/mouse is attached.
  • docs/RESCUE.md — recovery steps if the display becomes unusable (including console/getty recovery).