This is one of multiple possible extended definitions for timex, to allow future user space to keep working while defining time_t to 64-bit. The idea is that clock_adjtime() will take the new structure, which has an identical layout between 32-bit and 64-bit tasks, so we can use the compat_sys_clock_adjtime() function to always handle the old 32-bit layout, and use sys_clock_adjtime() to handle the new layout, without introducing an extra compat function.
Alternatives to this approach are: - define a new __kernel_timex that only differs in the size of the timex->time member, so we can keep using the old definition in source form, but with the new timeval definition. This requires adding an extra system call on 64-bit machines, to handle all three layouts. - use some of the padding words to store the upper half of the time_t. This allows us to keep using the existing system calls, but requires source-level changes in every user program to actually access the new data. Signed-off-by: Arnd Bergmann <[email protected]> --- include/uapi/linux/timex.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/include/uapi/linux/timex.h b/include/uapi/linux/timex.h index 92685d826444..80c429ecdf4e 100644 --- a/include/uapi/linux/timex.h +++ b/include/uapi/linux/timex.h @@ -92,6 +92,50 @@ struct timex { int :32; int :32; int :32; }; + +/* + * __kernel_timex is the new structure that uses the same layout + * as timex on 64-bit machines + */ +struct __kernel_timex_timeval { + long long tv_sec; + long long tv_usec; +}; + +struct __kernel_timex { + unsigned int modes; /* mode selector */ + unsigned int :32; /* pad */ + long long offset; /* time offset (usec) */ + long long freq; /* frequency offset (scaled ppm) */ + long long maxerror; /* maximum error (usec) */ + long long esterror; /* estimated error (usec) */ + int status; /* clock command/status */ + unsigned int :32; /* pad */ + long long constant; /* pll time constant */ + long long precision; /* clock precision (usec) (read only) */ + long long tolerance; /* clock frequency tolerance (ppm) + * (read only) + */ + struct __kernel_timex_timeval time;/* (read only, except for ADJ_SETOFFSET) */ + long long tick; /* (modified) usecs between clock ticks */ + + long long ppsfreq; /* pps frequency (scaled ppm) (ro) */ + long long jitter; /* pps jitter (us) (ro) */ + int shift; /* interval duration (s) (shift) (ro) */ + unsigned int :32; /* pad */ + long long stabil; /* pps stability (scaled ppm) (ro) */ + long long jitcnt; /* jitter limit exceeded (ro) */ + long long calcnt; /* calibration intervals (ro) */ + long long errcnt; /* calibration errors (ro) */ + long long stbcnt; /* stability limit exceeded (ro) */ + + int tai; /* TAI offset (ro) */ + + int :32; int :32; int :32; int :32; + int :32; int :32; int :32; int :32; + int :32; int :32; int :32; +}; + /* * Mode codes (timex.mode) */ -- 2.1.0.rc2 _______________________________________________ Y2038 mailing list [email protected] https://lists.linaro.org/mailman/listinfo/y2038
