SUMMARY

On platforms where the epoll_event struct is padded (>= 64 bit architectures except amd64), the padding is reported uninitialized unless the program explicitly uses memset.

STEPS TO REPRODUCE
1. On powerpc64, compile and run

#include <sys/epoll.h>
int main(int, char **)
{
    epoll_event evt;
    evt.events = 0;
    evt.data.ptr = nullptr;
    epoll_ctl(0, EPOLL_CTL_ADD, 0, &evt);
}

OBSERVED RESULT

The padding is reported as uninitialized.

EXPECTED RESULT

No error, or an indication that this is mostly harmless.