To solve the y2038 problem in input_event, I had some attempts before [1], and this is the second one.
We can force userspace to use monotonic time in event timestamp, so the 'struct timeval' is enough to keep y2038-safe, as Arnd suggested. But we can not find a way to make kernel compatible with old binaries, which use realtime, and there are still some devices, which depend on realtime. So I get a idea to add a new evdev interface, which is y2038 safe. And userspace can switch between the old and new interface via ioctl. The patch series add three evdev interface type: - EV_IF_LEGACY send event by input_event. This is the default option, keep kernel backward compatible. - EV_IF_RAW send event by input_value, which doesn't contain a timestamp. If userspace don't need the event timestamp, EV_IF_RAW is the best choice. - EV_IF_COMPOSITE send event by input_composite_event. This is a new structure, which append a nanosecond timestamp after input_value. Since the input_value and s64 are the same size, so you can treat it as two input_value. Actually, evdev is not interesting in event timestamp, all it should do is to keep event sequences, and evdev already satisfy this. So in the kernel, the event should only store in input_value, input_event and input_composite_event is used by userspace only. I also wrote a evtest tool [2], to validate those patches. The tool create a evdev device via uinput, and inject event through evdev or uinput, with different interface type. I have run this test in my Dragonboard 410c, by this command: $ evtest -l -r -c -n 400000 No problem found, all events are received normally. [1]: previous patches - https://www.spinics.net/lists/y2038/msg00959.html [2]: evtest source code - https://github.com/wengpingbo/evtest WEN Pingbo (3): input: evdev: introduce new evdev interface input: evdev: add new ioctl EVIOCSIFTYPE / EVIOCGIFTYPE uinput: convert input_event to input_value drivers/input/evdev.c | 117 ++++++++++++++++------------------ drivers/input/input-compat.c | 148 ++++++++++++++++++++++++++++--------------- drivers/input/input-compat.h | 48 ++++++++++---- drivers/input/misc/uinput.c | 23 ++++--- include/linux/input.h | 12 ---- include/linux/uinput.h | 2 +- include/uapi/linux/input.h | 27 ++++++++ 7 files changed, 225 insertions(+), 152 deletions(-) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
