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From: Bill Fenner <fenner@research.att.com>
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Date: Wed, 30 Jul 2003 21:52:48 -0700
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cc: standards@freebsd.org
Subject: Re: struct timeval
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I think we can do this with old-binary-on-new-kernel compatability,
by putting in explicit padding that can be zeroed by the kernel.
new-binary-on-old-kernel should also work, since the explicit padding
in the struct can put the time_t in the right place.

My strawman is something like:

struct timeval {
#ifdef __sparc64__
	uint32_t	__pad;
#endif
	time_t		tv_sec;
#ifdef __alpha__
	uint32_t	__pad;
#endif
	suseconds_t	tv_usec;
}

and anything that returns a timeval has to

#if defined(__sparc64__) || defined(__alpha__)
	tv->__pad = 0;
#endif

POSIX 1003.1-2001 says:

sys/time.h - time types

#include <sys/time.h> 

The <sys/time.h> header shall define the timeval structure that includes
at least the following members:

time_t         tv_sec      Seconds.
suseconds_t    tv_usec     Microseconds. 

so the optional padding is OK and the type of tv_sec is correct.

  Bill