On 11/27/2017 09:00 AM, Arnd Bergmann wrote:
b) Extend the approach taken by the x32 ABI, and use the 64-bit native structure layout for rusage on all architectures with new system calls that is otherwise compatible. A possible problem here is that we end up with incompatible definitions of rusage between /usr/include/linux/resource.h and /usr/include/bits/resource.h
c) Change the definition of struct rusage to be independent of time_t. This is the easiest change, as it does not involve new system call entry points, but it has the risk of introducing compile-time incompatibilities with user space sources that rely on the type of ru_utime and ru_stime.
I'm picking approch c) for its simplicity, but I'd like to hear from others whether they would prefer a different approach.
(c) would break programs like GNU Emacs, which copy ru_utime and ru_stime members into struct timeval variables.
All in all, (b) sounds like it would be better for programs using glibc, as it's more compatible with what POSIX apps expect. Though I'm not sure what problems are meant by "possible ... incompatible definitions"; perhaps you could elaborate.