Date: Sun, 29 May 2005 20:11:04 -0700 (PDT)
Message-Id: <20050529.201104.59476605.davem@davemloft.net>
To: akpm@osdl.org
Cc: phdm@macqel.be, linux-kernel@vger.kernel.org, uclinux-dev@uclinux.org
Subject: Re: PATCH : ppp + big-endian = kernel crash
From: "David S. Miller" <davem@davemloft.net>
In-Reply-To: <20050529195245.33f36253.akpm@osdl.org>
References: <200505292138.j4TLcrJ28536@mail.macqel.be>
	<20050529.145509.82051753.davem@davemloft.net>
	<20050529195245.33f36253.akpm@osdl.org>
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From: Andrew Morton <akpm@osdl.org>
Date: Sun, 29 May 2005 19:52:45 -0700

> > All these patches to PPP and friends are merely papering over the
> > larger problem.
> 
> It's not a thing we want to do in the general case, sure.  But it's
> reasonable to identify those bits of net code which the nommu people care
> about and look to see if there's some sane workaround to get them going.
> 
> Otherwise, things like PPP will simply unavailable to some architectures...

Some time ago there was a proposal that would allow appropriate
handling of these sorts of things.

Accessors to packet headers would go through a macro, and this
along with some other defines would allow an architecture to
decide between two schemes:

1) Use normal loads and stores, let trap handler take care of
   unaligned cases.
2) Use something akin to get_unaligned(), no trap handler stuff.

Sure, to make things faster we can do something like this PPP
patch, but it needs lots of work, first of all you need to
replace this:

	for ( ... )
		p[i-1] = p[i];

stuff with a proper memmove() call.
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