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The input events use struct timeval to store event time, unfortunately this structure is not y2038 safe and is being replaced in kernel with y2038 safe structures. Because of ABI concerns we can not change the size or the layout of structure input_event, so we opt to re-interpreting the 'seconds' part of timestamp as an unsigned value, effectively doubling the range of values, to year 2106. Newer glibc that has support for 32 bit applications to use 64 bit time_t supplies __USE_TIME_BITS64 define [1], that we can use to present the userspace with updated input_event layout. The updated layout will cause the compile time breakage, alerting applications and distributions maintainers to the issue. Existing 32 binaries will continue working without any changes until 2038. Ultimately userspace applications should switch to using monotonic or boot time clocks, as realtime clock is not very well suited for input event timestamps as it can go backwards (see a80b83b7b8 "Input: evdev - add CLOCK_BOOTTIME support" by by John Stultz). With monotonic clock the practical range of reported times will always fit into the pair of 32 bit values, as we do not expect any system to stay up for a hundred years without a single reboot. [1] https://sourceware.org/glibc/wiki/Y2038ProofnessDesign Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Acked-by: Peter Hutterer <peter.hutterer@who-t.net> Patchwork-Id: 10148083 Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.