From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52331) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cYtnM-0000FR-Qw for qemu-devel@nongnu.org; Wed, 01 Feb 2017 07:13:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cYtnL-0004cB-Sm for qemu-devel@nongnu.org; Wed, 01 Feb 2017 07:13:52 -0500 References: <20170126110435.2777-1-berrange@redhat.com> <20170126110435.2777-4-berrange@redhat.com> <20170126123530.GB23095@lemon.Home> <20170126132708.GB29127@redhat.com> <6a9aeec8-d4ee-a0aa-7e04-0ee4295fef80@redhat.com> From: Max Reitz Message-ID: <8a13c995-c094-2704-c770-214132b2d6cf@redhat.com> Date: Wed, 1 Feb 2017 13:13:39 +0100 MIME-Version: 1.0 In-Reply-To: <6a9aeec8-d4ee-a0aa-7e04-0ee4295fef80@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="CIFOH35G6ku8kV4xTB6gfoRndecfOUPn6" Subject: Re: [Qemu-devel] [PATCH v1 3/6] qemu-img: add support for -n arg to dd command List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , "Daniel P. Berrange" , Fam Zheng Cc: Kevin Wolf , qemu-devel@nongnu.org, qemu-block@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --CIFOH35G6ku8kV4xTB6gfoRndecfOUPn6 From: Max Reitz To: Eric Blake , "Daniel P. Berrange" , Fam Zheng Cc: Kevin Wolf , qemu-devel@nongnu.org, qemu-block@nongnu.org Message-ID: <8a13c995-c094-2704-c770-214132b2d6cf@redhat.com> Subject: Re: [Qemu-devel] [PATCH v1 3/6] qemu-img: add support for -n arg to dd command References: <20170126110435.2777-1-berrange@redhat.com> <20170126110435.2777-4-berrange@redhat.com> <20170126123530.GB23095@lemon.Home> <20170126132708.GB29127@redhat.com> <6a9aeec8-d4ee-a0aa-7e04-0ee4295fef80@redhat.com> In-Reply-To: <6a9aeec8-d4ee-a0aa-7e04-0ee4295fef80@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 30.01.2017 19:37, Eric Blake wrote: > On 01/26/2017 07:27 AM, Daniel P. Berrange wrote: >> On Thu, Jan 26, 2017 at 08:35:30PM +0800, Fam Zheng wrote: >>> On Thu, 01/26 11:04, Daniel P. Berrange wrote: >>>> The -n arg to the convert command allows use of a pre-existing image= , >>>> rather than creating a new image. This adds a -n arg to the dd comma= nd >>>> to get feature parity. >>> >>> I remember there was a discussion about changing qemu-img dd's defaul= t to a >>> "conv=3Dnocreat" semantic, if so, "-n" might not be that useful. But = that part >>> hasn't made it into the tree, and I'm not sure which direction we sho= uld take. >>> (Personally I think default to nocreat is a good idea). >> >> Use nocreat by default would be semantically different from real "dd" >> binary which feels undesirable if the goal is to make "qemu-img dd" >> be as consistent with "dd" as possible. >> >> It would be trivial to rewrite this patch to add support for the "conv= " >> option, allowing the user to explicitly give 'qemu-img dd conv=3Dnocre= at' >> instead of my 'qemu-img dd -n' syntax, without changing default semant= ics. >=20 > Adding 'conv=3Dnocreat' (and not '-n') feels like the right way to me. The original idea was to make conv=3Dnocreat a mandatory option, I think.= qemu-img was supposed error out if the user did not specify it. Max --CIFOH35G6ku8kV4xTB6gfoRndecfOUPn6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQFGBAEBCAAwFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAliR0PMSHG1yZWl0ekBy ZWRoYXQuY29tAAoJEPQH2wBh1c9AUfgH/31e1FCnnpEab6D3+O9zzOxpTwVVOKK0 1Rq6gLPOobsZaSF+8VbRMzqO//YgS0XZmOIG8NLMM9P4AAU2Ve6Cqay0xKr/u7XR vjHa8/hX7PEY8y2NgOGxlJ7KL9vV4FitgUj2hmR3GfpvS0Fcj/Hx3Fs9Klq4jbiB qTCe0TQdgCm7nFeBQaZnJG3DESmp0cAvKdp5sIqnzX18MrGkm6LaOgQ4U8rbtKDf wIki0LhRvszPqfkY3Z3koxBLhmd8o9xfR3ZaMXehWZcyCbsasX8k5Dzyu/vvBlLF zyotb6ypyR905Erxk+z7K3K3YhrRXL24oqrjhl0CVVZQ3fA7f1Hdd8Q= =nMu/ -----END PGP SIGNATURE----- --CIFOH35G6ku8kV4xTB6gfoRndecfOUPn6--