On Fri, Nov 10, 2017 at 11:42 PM, Deepa Dinamani firstname.lastname@example.org wrote:
The series is a preparation series for individual architectures to use 64 bit time_t syscalls in compat and 32 bit emulation modes.
This is a follow up to the series Arnd Bergmann posted: https://sourceware.org/ml/libc-alpha/2015-05/msg00070.html
Big picture is as per the lwn article: https://lwn.net/Articles/643234/
The series is directed at converting posix clock syscalls: clock_gettime, clock_settime, clock_getres and clock_nanosleep to use a new data structure __kernel_timespec at syscall boundaries. __kernel_timespec maintains 64 bit time_t across all execution modes.
vdso will be handled as part of each architecture when they enable support for 64 bit time_t.
The compat syscalls are repurposed to provide backward compatibility by using them as native syscalls as well for 32 bit architectures. They will continue to use timespec at syscall boundaries.
CONFIG_64_BIT_TIME controls whether the syscalls use __kernel_timespec or timespec at syscall boundaries.
The series does the following:
- Enable compat syscalls unconditionally.
- Add a new __kernel_timespec type to be used as the data structure for all the new syscalls.
- Add new config CONFIG_64BIT_TIME(intead of the CONFIG_COMPAT_TIME in  and  to switch to new definition of __kernel_timespec. It is the same as struct timespec otherwise.
Arnd Bergmann (1): y2038: introduce CONFIG_64BIT_TIME
The series looks good to me overall, and I've added it to my build-testing tree to see if it shows any regressions in random configurations.
I had on concern about x32, maybe we should check for "COMPAT_USE_64BIT_TIME" before zeroing out the tv_nsec bits.
Regarding CONFIG_COMPAT_TIME/CONFIG_64BIT_TIME, would it help to just leave out that part for now and unconditionally define '__kernel_timespec' as 'timespec' until we are ready to convert the architectures?