cvs commit: src/include ar.h

[Yar Tikhiy]

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? ;-)

-- 
Yar