From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by 2002:a17:906:3b11:0:0:0:0 with SMTP id g17csp2377774ejf; Mon, 8 Aug 2022 01:36:09 -0700 (PDT) X-Google-Smtp-Source: AA6agR6DhD2HjCe41NLx8IL7g/9S/xMVXIASPJAVEzSfY9ZudCjkf6ml0Gcm9uNFnbDbJuVQpsms X-Received: by 2002:a05:620a:40cf:b0:6b1:41dd:9710 with SMTP id g15-20020a05620a40cf00b006b141dd9710mr13042240qko.727.1659947768927; Mon, 08 Aug 2022 01:36:08 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1659947768; cv=none; d=google.com; s=arc-20160816; b=YgD+Om65CoBQiC5wHFSKkK/p/a/Ck0HURHOuOBPsLkzcnAVlLwe9T37/uaGFMqjJAG mDcliPvd8xg92w0hhRKJ+wBKPk/AQBdOw/wFc24636W5Ut48R5V9DZ5ueUm8owCdpzOf y4yZGEsrZq08ByyujLaa9ArHasEipswPehuXdBKgvb4TOpJD0YLTbYjZiuw/x8OuL5M6 T2H2F1rtBvdsjModOWyiTcJlEulEZt8GdqeWuvOt44egpH/X17RW0T8i6+rXgE4ySApq JkouDQUeQOjWLfXHpOAme5bHGY25tqW4mPKLv2Hi4oEISgjnunZ+MnpB/CoYWUmur/Ct LJgw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:in-reply-to :content-transfer-encoding:content-disposition:mime-version :references:message-id:subject:cc:to:from:date:dkim-signature; bh=bPq0LjEk3658WPodM0qnuCrIiCUmWdFxflN6qSyNcdo=; b=G3SJuN2CI9CeoYrXb52DGvf20eQki0wDSQZlO/rkpW53uzNPKaAPxTvdlvAE1XIwAE MKj7CvaP28YIxX24ewSvUmja1aycSIlVcZ+rhvf44BU3KIwocxm0h6tez/uFy+hWJK4x luw1+t/Gx2WMloT+OvYbzK0lk7EGOD+5qrLDBh7P7k0y0uRI2nsjUG4e4SgNVf1C0oBr TfTBljKSarXrOL9rH32TWa9l2m80R2whXd549K2ZNZnhJ4vgaRaXkMkEVbqHHCk2fonZ RAPkKBO5DasM6FJ9AuGCYNBIw+OV8U44BqbBC0qtn1sk62rn6fRYcI9wv1ae1hMzky4+ +JNw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=RvvTOOiZ; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org. [209.51.188.17]) by mx.google.com with ESMTPS id k8-20020a05622a03c800b00342f77a89f2si2020998qtx.642.2022.08.08.01.36.08 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Mon, 08 Aug 2022 01:36:08 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-arm-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=RvvTOOiZ; spf=pass (google.com: domain of qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-arm-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:35746 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oKyF5-0004Af-69 for alex.bennee@linaro.org; Mon, 08 Aug 2022 04:36:08 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52676) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKyDq-000487-3U for qemu-arm@nongnu.org; Mon, 08 Aug 2022 04:34:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:49610) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKyDl-0006gM-Bp for qemu-arm@nongnu.org; Mon, 08 Aug 2022 04:34:47 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659947681; 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=bPq0LjEk3658WPodM0qnuCrIiCUmWdFxflN6qSyNcdo=; b=RvvTOOiZb+CkzS3KOMMmxA5A0XL3ox07ps8Kndbzq5bWuLeSGsO1XDbG3KYImKjQsQsDOw qD52iWPUtjSzglhzQ8dcDMZRqUiLO9JP0gfa+CtaJrVh/mfEVuIFL+GLM9yDT3dLJH2Q1N JdNOHc2Rs4JOXd7fl8qy6Vt16ESnE0s= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-81-FBJP2ItUPzCGHkbUgCY7XQ-1; Mon, 08 Aug 2022 04:34:35 -0400 X-MC-Unique: FBJP2ItUPzCGHkbUgCY7XQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 542C618A6523; Mon, 8 Aug 2022 08:34:34 +0000 (UTC) Received: from redhat.com (unknown [10.39.192.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D8FA42166B29; Mon, 8 Aug 2022 08:34:31 +0000 (UTC) Date: Mon, 8 Aug 2022 10:34:30 +0200 From: Kevin Wolf To: Markus Armbruster Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Peter Maydell , 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 Message-ID: References: <20220714182836.89602-6-wuhaotsh@google.com> <87ilnuda33.fsf@pond.sub.org> <877d3odpm8.fsf@pond.sub.org> <87bkt0c9gf.fsf@pond.sub.org> <87lerzxnc5.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87lerzxnc5.fsf@pond.sub.org> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@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-arm@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-arm-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-arm" X-TUID: sy0hrL815QCN Am 08.08.2022 um 08:26 hat Markus Armbruster geschrieben: > Daniel P. Berrangé writes: > > > On Thu, Aug 04, 2022 at 05:30:40PM +0200, Markus Armbruster wrote: > >> Daniel P. Berrangé writes: > >> > >> > On Thu, Aug 04, 2022 at 04:56:15PM +0200, Markus Armbruster wrote: > >> >> Daniel P. Berrangé writes: > >> >> > >> >> > 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 eFuses. > >> >> >> > > 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" disk 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 parallel 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 opinion on > >> >> >> > whether IF_PFLASH is a good match), let's add a new one. But a specific > >> >> >> > new one, not just "other". > >> >> >> > >> >> >> I think the common thread is "this isn't what anybody actually thinks > >> >> >> of as being a 'disk', but we would like to back it with a block device > >> >> >> 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 want > >> >> > to create, and leave -drive out of the picture entirely > >> >> > >> >> -drive is our only means to configure onboard devices. > >> >> > >> >> We've talked about better means a few times, but no conclusions. I can > >> >> 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. > >> > >> True, but the vast majority of onboard block devices doesn't come with > >> such properties. Please see > >> > >> Subject: On configuring onboard block devices with -blockdev (was: [PATCH 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. Machine properties are also not what we really want, but just a workaround. How about implementing the real thing, providing qdev properties for built-in devices? Looking at a few random users of drive_get(), they look like this: DriveInfo *dinfo = drive_get(...); dev = qdev_new("driver-type"); qdev_prop_set_drive(dev, "drive", blk_by_legacy_dinfo(dinfo)); qdev_realize_and_unref(...); What if we assigned a name to every built-in device and had a qdev_new_builtin(type, id) that applies qdev properties given on the command line to the device? Could be either with plain old '-device' (we're already doing a similar thing with default devices where adding -device for the existing device removes the default device) or with a new command line option. The qdev_prop_set_drive() would then become conditional and would only be done if the property wasn't already set in qdev_new_builtin(). Or maybe a new function that checks for conflicting -drive and -device. Though that part is just implementation details. Kevin