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[209.51.188.17]) by mx.google.com with ESMTPS id bz21-20020a05622a1e9500b0031f3851a513si454332qtb.89.2022.07.28.06.35.54 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 28 Jul 2022 06:35:54 -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=Jk+XGeZH; 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]:53228 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oH3g9-0000nz-2D for alex.bennee@linaro.org; Thu, 28 Jul 2022 09:35:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33468) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oH3ae-0005ew-CQ for qemu-devel@nongnu.org; Thu, 28 Jul 2022 09:30:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:46394) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oH3ac-0002tf-Pf for qemu-devel@nongnu.org; Thu, 28 Jul 2022 09:30:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659015010; 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: in-reply-to:in-reply-to:references:references; bh=v4NDBabO87eMgw//tm5IPRl769IKkg8ma5inkeF5aJk=; b=Jk+XGeZHh+AfnXww3tflHD02CWsjUEwJZDGI+1uTr2roepVErKCAf7sb9p/N4sgTqM1AOA IfU/Ou4VKwUeA5VvYyeb1nbxCv3sx+GlANESR5TIXfjiiX9/V/GBvY2mQdVg+/5ERjOil5 VKsi8eLwv+nR0lB+QAVUQ/+/6sJJTlY= 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-218-YXXznu3sOuO5zX7Aqn0Xqw-1; Thu, 28 Jul 2022 09:30:04 -0400 X-MC-Unique: YXXznu3sOuO5zX7Aqn0Xqw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9C746801755; Thu, 28 Jul 2022 13:30:03 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 209DDC04482; Thu, 28 Jul 2022 13:29:59 +0000 (UTC) Date: Thu, 28 Jul 2022 15:29:58 +0200 From: Kevin Wolf To: Peter Maydell Cc: Markus Armbruster , 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: <20220714182836.89602-1-wuhaotsh@google.com> <20220714182836.89602-6-wuhaotsh@google.com> <87ilnuda33.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 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_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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: 1ZSTU2voWxUi Am 28.07.2022 um 11:46 hat Peter Maydell geschrieben: > 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... How confident are we that no board will ever have two devices of this kind? As long as every board has at most one, if=other is a bad user interface in terms of descriptiveness, but still more or less workable as long as you know what it means for the specific board you use. But if you have more than one device, it becomes hard to predict which device gets which backend - it depends on the initialisation order in the code then, and I'm pretty sure that this isn't something that should have significance in external interfaces and therefore become a stable API. Kevin