From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59692) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eFlna-0003FM-Au for qemu-devel@nongnu.org; Fri, 17 Nov 2017 13:55:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eFlnZ-0000H7-C3 for qemu-devel@nongnu.org; Fri, 17 Nov 2017 13:55:34 -0500 References: <20171117164747.11525-1-eblake@redhat.com> <9279377e-9165-d6b9-930f-7949c2c1fb72@redhat.com> From: Eric Blake Message-ID: Date: Fri, 17 Nov 2017 12:55:25 -0600 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="78edtggCNEcahD8dj4iAKf9tRiHcFJbM3" Subject: Re: [Qemu-devel] [PATCH for-2.11] qcow2: fix image corruption on commit with persistent snapshot List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz , qemu-devel@nongnu.org Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, qemu-block@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --78edtggCNEcahD8dj4iAKf9tRiHcFJbM3 From: Eric Blake To: Max Reitz , qemu-devel@nongnu.org Cc: kwolf@redhat.com, vsementsov@virtuozzo.com, qemu-block@nongnu.org Message-ID: Subject: Re: [Qemu-devel] [PATCH for-2.11] qcow2: fix image corruption on commit with persistent snapshot References: <20171117164747.11525-1-eblake@redhat.com> <9279377e-9165-d6b9-930f-7949c2c1fb72@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 11/17/2017 12:46 PM, Eric Blake wrote: >> >> The test fails with -m32 and probably also on Big Endian architectures= , >> because the bitmap hash differs. >=20 > Oh my. Thanks for the rapid testing. >=20 >> We could "fix" this by replacing the 2100 by a 2102, so for both bit >> widths rounding is the same. Actually, thinking about it more, are we sure that a .qcow2 image created on an -m32 host can be properly loaded on a 64-bit host, despite their different rounded-up sizes for the bitmaps? If the difference in hash is due only to the in-memory representation, but the on-disk layout is identical, then we are safe; but if the difference in hash is visible on-disk, then we have a real bug in our qcow2 specification or implementation of persistent bitmaps. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --78edtggCNEcahD8dj4iAKf9tRiHcFJbM3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAloPMJ0ACgkQp6FrSiUn Q2pgLwgAgaCvuJRYk7Z5F4RV4cgA34U7q/JfckAsR8a+5+NU18V3XWz6Bt3hMJnz hEOfdTZy4GFVlYZDSr5qvHEtglQIMa71jtMH5MuBkJauSz+QuVq3wegKSOJ0aSHI 9gb277J+kQXZlN0dCMwtCBCESWDixoUyRtT2ygwCfswrVv3gCHzYmAo63TKi5yBH 1VBZC9E4P41s10dvsgZCdtxAdUC2N9pnK8N6tn5N3huIEIYNxOjs79/H8dlQCxsT 6+7+t1Rq1ocqeMzFAu8onuiLEnKH0lHxEKWIpXHrq1CfbbQQm3FukutnUZKWVI4C N6iYAkrq8TQdesNs217FYVzMRIT6zg== =6bKx -----END PGP SIGNATURE----- --78edtggCNEcahD8dj4iAKf9tRiHcFJbM3--