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Date: Mon, 05 Feb 2001 13:00:51 +0100
From: Manfred Spraul <manfred@colorfullife.com>
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To: "Stephen C. Tweedie" <sct@redhat.com>
CC: Linus Torvalds <torvalds@transmeta.com>,
        Christoph Hellwig <hch@caldera.de>, Steve Lord <lord@sgi.com>,
        linux-kernel@vger.kernel.org, kiobuf-io-devel@lists.sourceforge.net,
        Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait /notify 
 + callback chains
In-Reply-To: <20010201220744.K11607@redhat.com> <Pine.LNX.4.10.10102031224210.8867-100000@penguin.transmeta.com> <20010205110336.A1167@redhat.com>
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"Stephen C. Tweedie" wrote:
> 
> You simply cannot do physical disk IO on
> non-sector-aligned memory or in chunks which aren't a multiple of
> sector size.

Why not?

Obviously the disk access itself must be sector aligned and the total
length must be a multiple of the sector length, but there shouldn't be
any restrictions on the data buffers.

I remember that even Windoze 95 has scatter-gather support for physical
disk IO with arbitraty buffer chunks. (If the hardware supports it,
otherwise the io subsystem will copy the data into a contiguous
temporary buffer)

--
	Manfred
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