On Fri, Jan 11, 2019 at 01:33:09PM -0500, Nicolas Pitre wrote: > 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
This all sounds familiar, and I suspect this is the fix: https://lkml.org/lkml/2019/1/8/1379 Regards, Vito Caputo
