From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50727) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKUNW-0003Ra-1V for qemu-devel@nongnu.org; Fri, 13 Sep 2013 10:29:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VKUNQ-0007pb-2V for qemu-devel@nongnu.org; Fri, 13 Sep 2013 10:29:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51064) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VKUNP-0007pQ-QX for qemu-devel@nongnu.org; Fri, 13 Sep 2013 10:29:39 -0400 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r8DETc6G023798 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 13 Sep 2013 10:29:38 -0400 Message-ID: <52332150.8020804@redhat.com> Date: Fri, 13 Sep 2013 16:29:36 +0200 From: Max Reitz MIME-Version: 1.0 References: <1378106712-29856-1-git-send-email-mreitz@redhat.com> <5231D673.6050907@redhat.com> <5231DCA6.7090004@redhat.com> <20130913095753.GC2804@dhcp-200-207.str.redhat.com> <5232E78A.2030406@redhat.com> <52330516.10503@redhat.com> In-Reply-To: <52330516.10503@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v5 0/8] Add metadata overlap checks List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: Kevin Wolf , qemu-devel@nongnu.org, Stefan Hajnoczi On 2013-09-13 14:29, Eric Blake wrote: > On 09/13/2013 04:23 AM, Max Reitz wrote: >> [=E2=80=A6] >> I think, we should first take care of the command line interface and >> about QMP later (that is, if you agree on generally allowing >> modification of the qcow2 runtime options through QMP). There, we coul= d >> offer both one boolean per mask element and an integer option, probabl= y >> the boolean flags taking precedence. > I'm fine if it is JUST a command-line parameter (all-or-nothing, turned > on when you boot qemu, and not something we can be changing on the fly). > But if we ever do want live changing via QMP, do NOT expose it as a r= aw > int, but only as named bools. Another idea: Instead of providing an integer for "shorthand"=20 manipulations, what do you think of a string parameter (such as -o=20 cache=3Dfoo right now, although I do know -o cache isn't even document=20 anymore and provided only for compatibility reasons, it seems to me)=20 which will automatically be translated to the right settings? I'm=20 thinking of: - overlap-check=3Dnone (no checks at all) - overlap-check=3Dconstant (only checks who can be performed in constan= t=20 time, i.e., main header, active L1, refcount table and snapshot table) - overlap-check=3Dcached (only checks which don't require disk access,=20 i.e. the current (and as I'd propose, future) default) - overlap-check=3Dall (all checks, including those requiring disk acces= s=20 (i.e., overlaps on inactive L2 tables)) These would then provide templates which can be further refined through=20 the booleans (as is the case with -o cache right now). Max