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Re: [Xen-devel] The two image formats called qcow

To: Kevin Wolf <kwolf@xxxxxxx>, Otavio Salvador <otavio@xxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] The two image formats called qcow
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Wed, 26 Mar 2008 14:02:39 +0000
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On 26/3/08 13:54, "Kevin Wolf" <kwolf@xxxxxxx> wrote:

> ioemu: Fix L1 table endianess of qcow images created by tapdisk
> 
> The qemu/ioemu implementation of the qcow format uses a big endian L1
> table. tapdisk omits the necessary conversion, so qcow images have the
> wrong endianess and cannot be read by correct implementations of qcow.
> 
> This patch detects broken tapdisk images and converts their L1 tables to
> big endian when the image file is opened in ioemu for the first time.
> The fixed image has a new flag EXTHDR_L1_BIG_ENDIAN set in the extended
> header.
> 
> Note that a converted image cannot be opened by tapdisk again.

Can we really tack an 'extended header' into a public format like qcow?

 -- Keir



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