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From: Sam Leffler <sam@errno.com>
Organization: Errno Consulting
To: "Poul-Henning Kamp" <phk@phk.freebsd.dk>,
	Scott Long <scottl@freebsd.org>
Date: Mon, 6 Oct 2003 17:53:28 -0700
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cc: arch@freebsd.org
Subject: Re: Alignment of disk-I/O from userland.
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On Monday 06 October 2003 04:11 pm, Poul-Henning Kamp wrote:
> In message <20031006163218.L55190@pooker.samsco.home>, Scott Long writes:
	...stuff deleted...
> >As for returning an error code for a buffer that we (arbitrarily) believe
> >to be too big to align, [...]
>
> I have never advocated returning an error based on "alignment and size",
> only based on alignment alone.

Imposing this restriction is a major semantic change that I consider a very 
bad idea.  You are basically imposing the semantics of O_DIRECT on all i/o 
operations going to a device.  I think it is important to give best effort to 
support unaligned operations `by default.  I can imagine restricting this to 
some upper size bound but existing applications, regardless of how well you 
consider them to be written, must continue to work.

	Sam