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To: olli@fromme.com
From: "M. Warner Losh" <imp@bsdimp.com>
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Cc: src-committers@FreeBSD.org, jilles@stack.nl, svn-src-all@FreeBSD.org,
	olli@FreeBSD.org, svn-src-head@FreeBSD.org, des@des.no
Subject: Re: svn commit: r211023 - head/usr.sbin/syslogd
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In message: <201008101956.o7AJu5ms044774@haluter.fromme.com>
            Oliver Fromme <olli@fromme.com> writes:
: 
: M. Warner Losh wrote:
:  > /*
:  >  * Macros to cast a struct sockaddr, or parts thereof.  struct
:  >  * sockaddr's alginment is loose to later be cast to a sockaddr_in or
:  >  * sockaddr_in6.  On architectures with strict alignment requirements,
:  >  * this leads to compiler warnings because the compiler doesn't know
:  >  * the ABI guarantees proper alignment.
:  >  */
:  > 
:  > But this leads me to think that the right fix might be:
:  > 
:  > /*
:  >  * Structure used by kernel to store most
:  >  * addresses.
:  >  */
:  > struct sockaddr {
:  > 	unsigned char	sa_len;		/* total length */
:  > 	sa_family_t	sa_family;	/* address family */
:  > 	char		sa_data[14];	/* actually longer; address value */
:  > } __aligned(4);
:  > 
:  > since that's what the ABI defines....
: 
: Yes, that would solve most of the problems, at least the ones
: related to struct sockaddr.
: 
: Can we make that change to struct sockaddr, or does it cause
: unwanted side-effects?
: 
: I could do a full "make universe" to test it, but it would
: probably take two days on my 9-current machine.

Just do it on MIPS.

You'll find that a number of structures are potentially already
allocated with less than required alignment.  There's about a dozen
places in the tree that would start to fail if we did this, or the
stronger form of __aligned(8).  We could add that to the other
structures, but then we're breaking ABI rules, I think.

Warner