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[209.51.188.17]) by mx.google.com with ESMTPS id s2-20020a0562140ca200b0047b33a59c68si2680781qvs.592.2022.08.07.23.29.04 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Sun, 07 Aug 2022 23:29:04 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=RdgNr+d7; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:59216 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oKwG8-0000eu-0c for alex.bennee@linaro.org; Mon, 08 Aug 2022 02:29:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60486) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKwDy-0008NX-Qy for qemu-devel@nongnu.org; Mon, 08 Aug 2022 02:26:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:23229) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKwDo-00053D-Jk for qemu-devel@nongnu.org; Mon, 08 Aug 2022 02:26:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659939998; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gWdWueB7+XfiKNF3K7VzJJT8dPSeIIMxzdwOinCQpJo=; b=RdgNr+d7iD6o6AXKtg1DWoLSLAm1D7JEkakDbzB5FsYm/mdnkEG8ICaFxxX44xYtjBF0Vy L95Bh+j+Pot56RxwHNn5wcpAEWOoHLhoD1V7lW23yJChs2o45FCCw3wwd+eX2N0+aN6dc/ nKg+bJwqzUzKSxOjQ29S+ICYXnAvuv4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-259-HRGlvtrfO6ipXd_D5O1oRw-1; Mon, 08 Aug 2022 02:26:36 -0400 X-MC-Unique: HRGlvtrfO6ipXd_D5O1oRw-1 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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id D986E1C05131; Mon, 8 Aug 2022 06:26:35 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.194.81]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3F2FA9457F; Mon, 8 Aug 2022 06:26:35 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 1A45821E6930; Mon, 8 Aug 2022 08:26:34 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: Peter Maydell , Kevin Wolf , Hao Wu , richard.henderson@linaro.org, qemu-arm@nongnu.org, qemu-devel@nongnu.org, venture@google.com, Avi.Fishman@nuvoton.com, kfting@nuvoton.com, hskinnemoen@google.com, f4bug@amsat.org, bin.meng@windriver.com, qemu-block@nongnu.org, thuth@redhat.com, Hanna Reitz Subject: Re: [PATCH v5 5/8] blockdev: Add a new IF type IF_OTHER References: <20220714182836.89602-1-wuhaotsh@google.com> <20220714182836.89602-6-wuhaotsh@google.com> <87ilnuda33.fsf@pond.sub.org> <877d3odpm8.fsf@pond.sub.org> <87bkt0c9gf.fsf@pond.sub.org> Date: Mon, 08 Aug 2022 08:26:34 +0200 In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Thu, 4 Aug 2022 16:44:32 +0100") Message-ID: <87lerzxnc5.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-devel" X-TUID: KgK9J0DTBhUc Daniel P. Berrang=C3=A9 writes: > On Thu, Aug 04, 2022 at 05:30:40PM +0200, Markus Armbruster wrote: >> Daniel P. Berrang=C3=A9 writes: >>=20 >> > On Thu, Aug 04, 2022 at 04:56:15PM +0200, Markus Armbruster wrote: >> >> Daniel P. Berrang=C3=A9 writes: >> >>=20 >> >> > On Thu, Jul 28, 2022 at 10:46:35AM +0100, Peter Maydell wrote: >> >> >> On Wed, 27 Jul 2022 at 20:03, Kevin Wolf wrote: >> >> >> > >> >> >> > Am 18.07.2022 um 11:49 hat Markus Armbruster geschrieben: >> >> >> > > An OTP device isn't really a parallel flash, and neither are e= Fuses. >> >> >> > > More fast-and-lose use of IF_PFLASH may exist in the tree, and= maybe of >> >> >> > > other interface types, too. >> >> >> > > >> >> >> > > This patch introduces IF_OTHER. The patch after next uses it = for an >> >> >> > > EEPROM device. >> >> >> > > >> >> >> > > Do we want IF_OTHER? >> >> >> > >> >> >> > What would the semantics even be? Any block device that doesn't = pick up >> >> >> > a different category may pick up IF_OTHER backends? >> >> >> > >> >> >> > It certainly feels like a strange interface to ask for "other" d= isk and >> >> >> > then getting as surprise what this other thing might be. It's >> >> >> > essentially the same as having an explicit '-device other', and I >> >> >> > suppose most people would find that strange. >> >> >> > >> >> >> > > If no, I guess we get to abuse IF_PFLASH some more. >> >> >> > > >> >> >> > > If yes, I guess we should use IF_PFLASH only for actual parall= el flash >> >> >> > > memory going forward. Cleaning up existing abuse of IF_PFLASH= may not >> >> >> > > be worth the trouble, though. >> >> >> > > >> >> >> > > Thoughts? >> >> >> > >> >> >> > If the existing types aren't good enough (I don't have an opinio= n on >> >> >> > whether IF_PFLASH is a good match), let's add a new one. But a s= pecific >> >> >> > new one, not just "other". >> >> >>=20 >> >> >> I think the common thread is "this isn't what anybody actually thi= nks >> >> >> of as being a 'disk', but we would like to back it with a block de= vice >> >> >> anyway". That can cover a fair range of possibilities... >> >> > >> >> > Given that, do we even want/have to use -drive for this ? We can= use >> >> > -blockdev for the backend and reference that from any -device we wa= nt >> >> > to create, and leave -drive out of the picture entirely >> >>=20 >> >> -drive is our only means to configure onboard devices. >> >>=20 >> >> We've talked about better means a few times, but no conclusions. I c= an >> >> dig up pointers, if you're interested. >> > >> > For onboard pflash with x86, we've just got properties against the >> > machine that we can point to a blockdev. >>=20 >> True, but the vast majority of onboard block devices doesn't come with >> such properties. Please see >>=20 >> Subject: On configuring onboard block devices with -blockdev (was: [PATC= H v4 6/7] hw/nvram: Update at24c EEPROM init function in NPCM7xx boards) >> Date: Mon, 15 Nov 2021 16:28:33 +0100 >> Message-ID: <875ystigke.fsf_-_@dusky.pond.sub.org> >> https://lists.gnu.org/archive/html/qemu-devel/2021-11/msg03173.html > > My take away from your mail there is that in the absence of better ideas > we should at least use machine properties for anything new we do so we > don't make the problem worse than it already is. It feels more useful > than inventing new IF_xxx possibilities for something we think is the > wrong approach already. The difficulty of providing machine properties for existing devices and the lack of adoption even for new devices make me doubt they are a viable path forward. In the message I referenced above, I wrote: If "replace them all by machine properties" is the way forward, we need to get going. At the current rate of one file a year (measured charitably), we'll be done around 2090, provided we don't add more (we've added quite a few since I did the first replacement). I figure this has slipped to the 22nd century by now. Yes, more uses of -drive are steps backward. But they are trivially easy, and also drops in the bucket. Machine properties are more difficult, and whether they actually take us forward seems doubtful.