From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37820) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vteir-0005Nc-34 for qemu-devel@nongnu.org; Thu, 19 Dec 2013 09:37:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vteil-00068j-Gk for qemu-devel@nongnu.org; Thu, 19 Dec 2013 09:37:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:26301) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vteil-00068W-6u for qemu-devel@nongnu.org; Thu, 19 Dec 2013 09:37:03 -0500 Date: Thu, 19 Dec 2013 16:40:37 +0200 From: "Michael S. Tsirkin" Message-ID: <20131219144037.GB17508@redhat.com> References: <1385001528-12003-1-git-send-email-imammedo@redhat.com> <1385001528-12003-6-git-send-email-imammedo@redhat.com> <87r4aaxdqt.fsf@blackfin.pond.sub.org> <20131125163642.4d832fd5@nial.usersys.redhat.com> <20131125160337.GB10326@redhat.com> <52937BA2.6020605@redhat.com> <52937E44.10503@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52937E44.10503@redhat.com> Subject: Re: [Qemu-devel] [PATCH 05/27] qapi: add SIZE type parser to string_input_visitor List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake Cc: peter.maydell@linaro.org, stefanha@redhat.com, stefanb@linux.vnet.ibm.com, qemu-devel@nongnu.org, hutao@cn.fujitsu.com, quintela@redhat.com, mjt@tls.msk.ru, mdroth@linux.vnet.ibm.com, Markus Armbruster , vasilis.liaskovitis@profitbricks.com, kraxel@redhat.com, aliguori@amazon.com, Igor Mammedov , Paolo Bonzini , marcel.a@redhat.com, lcapitulino@redhat.com, chegu_vinod@hp.com, afaerber@suse.de On Mon, Nov 25, 2013 at 09:43:48AM -0700, Eric Blake wrote: > On 11/25/2013 09:32 AM, Paolo Bonzini wrote: > > >> Yes please. Firing up a calculator to figure out how much is 1G is not > >> friendly, neither is firing it up to figure out what did management do > >> with QMP. It should be a text based interface not a binary one. > > Right now, QMP takes an 'int', which does not allow a suffix. Libvirt > prefers passing a value in 'bytes', rather than risking confusion on > whether a value in G was rounded (up, down? to nearest power of 10 or > power of 2?). Unfortunately, yes, that means you need a calculator when > parsing QMP logs to see whether the 1073741824 passed by libvirt is the > 1G you had in mind. > > HMP, qtest, and any other decent shell around raw QMP is more than > welcome to provide human-usable wrappers that takes "1G" as a string and > turns it into the raw int used by the underlying QMP. In fact, I > encourage it. How will it know 1G is not e.g. an ID? We can invent rules like "IDs should not start with a number", but these rules are better enforced in a single place for consistency, and it's likely too late to enforce that in HMP. > > This is unfortunately a counter-example to the rule that HMP commands > > should always be implemented in terms of their QMP counterparts. I do > > not believe this is really a problem. It can be fixed later; for now, I > > think "perfect is the enemy of good" applies. > > Hey - I just realized that now that we have anonymous unions, we could > theoretically extend QMP to allow a union between 'int' and 'string' - > if an 'int' is passed, it is in bytes; if a 'string' is passed, then > parse it the way HMP would (so the string "1G" would be equivalent to > the raw int 1073741824). But I don't know if it will help you (libvirt > will still prefer to use raw ints in any QMP log you read off of libvirt > interactions). Yes, I think that would address the issue. > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org >