I use Linux with the help of a braille display and the brltty daemon. It turns out that the latest mainline kernel I can work with comes from commit 231f8fd0cc. Anything past that and I lose the ability to read the console barely a few seconds after the system has booted as brltty is thrown a wrench and the braille display becomes completely inoperable.
Things get somewhat better with commit c96cf923a9 as brltty is not longer incapacitated, but some programs would randomly crash. Even the very first login attempt won't work as I soon as I hit enter after my user name the password prompt is skipped over, just like if the enter key had been hit twice. Then lynx (the text web browser) would crash as soon as I switch the virtual console with LeftAlt+FN. Mind you, this isn't easy to perform bisection in those conditions. And the worst commit i.e. 83d817f410 is marked for stable! :-( Some interaction with brltty must be at play here otherwise such breakage would never have survived up to the mainline kernel. As far as latest mainline is concerned, I managed to reproduce at least one of the unwelcome behavior change (hoping that's all there is to this issue) with a very simple test case so you won't have to learn braille to debug this: # from any vt, make sure tty40 is allocated and empty openvt -c 40 -f -- true # open it and wait on read() cat /dev/tty40 # from a second vt, simply open tty40 again true < /dev/tty40 # come back to the first vt and watch cat bailing out with EAGAIN. Please fix. Nicolas
