From owner-freebsd-current  Thu Jan 30  9: 7:59 2003
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To: jmallett@FreeBSD.ORG
Cc: marcel@xcllnt.net, current@FreeBSD.ORG
Subject: Re: Patch to teach config(8) about "platforms".
From: "M. Warner Losh" <imp@bsdimp.com>
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Any reason why the NetBSD approach to this problem won't work?  IMHO,
the meta-port should drive the derived ports.  The static parts of the
system are radically different between the different mips platforms.

Using the endian.h stuff as an example:

src/sys/arch/arc/include/endian.h is just "#include <sys/endian.h>"
src/sys/arch/arc/include/endian_machdep.h is

#define _BYTE_ORDER _LITTLE_ENDIAN
#include <mips/endian_machdep.h>

and src/sys/arch/mips/include/endian_machdep.h is a bunch of #defines
for assembler.

sys/endian.h looks like:

#define	_LITTLE_ENDIAN	1234	/* LSB first: i386, vax */
#define	_BIG_ENDIAN	4321	/* MSB first: 68000, ibm, net */
#define	_PDP_ENDIAN	3412	/* LSB first in word, MSW first in long */

#include <machine/endian_machdep.h>

...
#include <sys/cdefs.h>
#include <sys/types.h>

typedef u_int32_t	in_addr_t;
typedef u_int16_t	in_port_t;

__BEGIN_DECLS
uint32_t	htonl __P((uint32_t)) __attribute__((__const__));
uint16_t	htons __P((uint16_t)) __attribute__((__const__));
uint32_t	ntohl __P((uint32_t)) __attribute__((__const__));
uint16_t	ntohs __P((uint16_t)) __attribute__((__const__));
__END_DECLS

... (more macros/functions)

In this case, there's very little duplication of effort.

Warner

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