I have a machine still running bullseye. Recently the kernel was upgraded: Start-Date: 2025-12-13 21:49:11 Commandline: apt-get dist-upgrade Install: linux-image-5.10.0-37-amd64:amd64 (5.10.247-1, automatic) Upgrade: linux-image-amd64:amd64 (5.10.244-1, 5.10.247-1) End-Date: 2025-12-13 21:50:01
When I boot the new kernel, ttys 2 through 6 are covered by the character ¤, CURRENCY SIGN, Hex code point 00A4. (The character under the cursor appears as a space, as do the ends of any lines of text, though the text itself is not visible.) The arrow keys show bizarre behaviour: as the cursor moves around the screen, it looks like a Pac-Man eating the ¤s, changing them to their correct appearance, so that I can read what's meant to be there. But any new text (more login prompts) is invariably displayed as ¤. Only the ¤ characters are "real", the spaces are not. If I switch console and then switch back to it, everything has turned to ¤ again (except the cursor itself). If I login (blind), I see more odd spaces at the ends of what would be lines of text, and the characters where my coloured PS1 prompt would be written are coloured correctly, but the screen still shows only ¤ characters, and those few spaces. (Inverse-video is shown correctly too.) If I press Return enough times to scroll the screen, the coloured and inverse-video areas scroll correctly, but those odd spaces stay wherever they were generated. All this is with a /etc/default/console-setup containing: ACTIVE_CONSOLES="/dev/tty[1-6]" CHARMAP="UTF-8" CODESET="Uni2" FONTFACE="Terminus" FONTSIZE="12x24" VIDEOMODE= If I type (blind) setfont /usr/share/consolefonts/Uni2-Fixed16.psf.gz then all the ¤ characters change to © COPYRIGHT SIGN hex 00A9. Being smaller, it takes more rows and columns to cover the screen. Other fonts produce different characters at different sizes, but the screen is always totally covered by them. Note that tty1 is entirely unaffected by this problem, which is just as well. Running X with startx is also unaffected. You could have this problem and never notice it unless you happened to switch tty for whatever reason. Boot linux-image-5.10.0-36-amd64, 5.10.244-1, again, and everything behaves normally. Perhaps if you're still running bullseye, you could see whether you're similarly affected by the …-37-… / …247-1 kernel. Cheers, David.
