From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36555) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fShyC-0004Qb-5P for qemu-devel@nongnu.org; Tue, 12 Jun 2018 08:00:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fShy5-0008Da-Se for qemu-devel@nongnu.org; Tue, 12 Jun 2018 08:00:16 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49598 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fShy5-0008D6-OW for qemu-devel@nongnu.org; Tue, 12 Jun 2018 08:00:09 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F197FFD325 for ; Tue, 12 Jun 2018 12:00:08 +0000 (UTC) From: Markus Armbruster References: <20180608130846.22234-1-dgilbert@redhat.com> <20180608130846.22234-6-dgilbert@redhat.com> <87y3flilan.fsf@dusky.pond.sub.org> <20180611174958.GP2661@work-vm> <20180612053720.pp2xvb7r34o6ort7@sirius.home.kraxel.org> Date: Tue, 12 Jun 2018 14:00:05 +0200 In-Reply-To: <20180612053720.pp2xvb7r34o6ort7@sirius.home.kraxel.org> (Gerd Hoffmann's message of "Tue, 12 Jun 2018 07:37:20 +0200") Message-ID: <87k1r4use2.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 5/7] hmp: Add info commands for preconfig List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: "Dr. David Alan Gilbert" , imammedo@redhat.com, Markus Armbruster , Eduardo Habkost , qemu-devel@nongnu.org Gerd Hoffmann writes: > Hi, > >> > Now let's review the three commands: >> > >> > * Gerd, why does "info usbhost" have no QMP equivalent? > > Works only when running qemu directly, in the libvirt sandbox qemu > hasn't the permissions needed to scan the host usb bus so that would be > rather pointless ... I don't think this meets either of the two criteria: * I meets "makes no sense in QMP" only if QMP implies "can't scan host USB bus". Libvirt implies it, but QMP doesn't imply libvirt; it's its most important, not its sole user. * It meets "of use only for human users" only if we're convinced it's of no use to programs. To avoid speculation and endless arguments about what could or could not be of use, we've always stuck to "when in doubt, assume it could be of use". "Libvirt can't use it" falls short. "Any management application worth anything would deny QEMU the capability to scan the USB host bus, and thus wouldn't be able to use it" is exactly the argument we intended to avoid. QMP falling short of completeness in relatively unimportant ways like this one isn't exactly terrible. The most serious effect is probably serving as a bad example that leads to further arguments like this one. These are well worth avoiding, though.