cvs commit: src/include ar.h

[M. Warner Losh]

In message: <20061116090412.GB37133 at comp.chem.msu.su>
            Yar Tikhiy <yar at comp.chem.msu.su> writes:
: On Mon, Nov 13, 2006 at 10:19:58AM -0700, M. Warner Losh wrote:
: > : 
: > : BTW, you are responsible for the __packed in <netinet/ip.h>.  Please remove
: > : it.  The __CTASSERT() is enough to detect if heroic packing is ever needed.
: > : The only danger is if something has grown to depend on __packed reducing
: > : alignment as a side effect.  E.g., suppose we had a byte string containing
: > : a bytewise copy of a struct ip.  If the copy might be misaligned, then it
: > : should be copied to an actual struct ip before accessing it as a struct,
: > : but code that accesses it directly using ((struct ip *)&bs[N]) would work
: > : now due to the reduced alignment.  Places that really need __packed should
: > : probably use __aligned() to restore the natural alignment.
: > 
: > DO NOT REMOVE IT.  IT IS ABSOLUTELY REQUIRED FOR ARM TO WORK RIGHT.
: > If you want to remove it, then you must make sure arm works right
: > after it because I'll add it back.
: 
: Many years ago I was taught that comments in code could help to
: avoid such clashes in software development.  Is this true no more? ;-)

You don't add comments like:

	i++;	       // Add one to i.

This is a similar class.  It is for any compiler that has differing
alignment requirements than i386.

Warner