Re:Drgn: How the Linux kernel team at Facebook debugs the ke...
by ajuc on Tuesday December 14, 2021 @11:06AM
(#29553103)
Yup, the matrix for transforming hardware coordinates into software coordinates was saved in a config file using locale-specific number format. When user changed locale it remained in the previous format and if the change was English->German the matrix elements suddenly changed from 1.234 to 1234 :)
The funny thing is we had the issue once - reported it and added a workaround (added special handling for these config files that used locale-specific calibration tables), then a year later we updated the linux version and had the issue the opposite way till we removed our workaround :) But it was even more fun cause it bricked the devices (kernel panic on libinput startup = restart loop forever) :)
the details are here: https://github.com/jiixyj/libinput/commit/98793f6b435abf8c17...
The funny thing is we had the issue once - reported it and added a workaround (added special handling for these config files that used locale-specific calibration tables), then a year later we updated the linux version and had the issue the opposite way till we removed our workaround :) But it was even more fun cause it bricked the devices (kernel panic on libinput startup = restart loop forever) :)