From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D52CBC433DF for ; Mon, 25 May 2020 09:03:07 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A4E31206DD for ; Mon, 25 May 2020 09:03:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A4E31206DD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ilande.co.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:50938 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jd90k-0002f1-ME for qemu-devel@archiver.kernel.org; Mon, 25 May 2020 05:03:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43958) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jd8zo-00021x-PO for qemu-devel@nongnu.org; Mon, 25 May 2020 05:02:08 -0400 Received: from mail.ilande.co.uk ([2001:41c9:1:41f::167]:50268 helo=mail.default.ilande.uk0.bigv.io) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jd8zn-00015c-CW for qemu-devel@nongnu.org; Mon, 25 May 2020 05:02:08 -0400 Received: from host109-156-104-24.range109-156.btcentralplus.com ([109.156.104.24] helo=[192.168.1.65]) by mail.default.ilande.uk0.bigv.io with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jd8zi-0000Hl-66; Mon, 25 May 2020 10:02:05 +0100 To: Igor Mammedow , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= References: <20200510113505.10500-1-f4bug@amsat.org> <20200514120951.3588bc30@redhat.com> <58238d26-a9dc-0cc0-749d-6230d2646f75@amsat.org> <20200520120709.558a52ba@nas.mammed.net> From: Mark Cave-Ayland Autocrypt: addr=mark.cave-ayland@ilande.co.uk; keydata= mQENBFQJuzwBCADAYvxrwUh1p/PvUlNFwKosVtVHHplgWi5p29t58QlOUkceZG0DBYSNqk93 3JzBTbtd4JfFcSupo6MNNOrCzdCbCjZ64ik8ycaUOSzK2tKbeQLEXzXoaDL1Y7vuVO7nL9bG E5Ru3wkhCFc7SkoypIoAUqz8EtiB6T89/D9TDEyjdXUacc53R5gu8wEWiMg5MQQuGwzbQy9n PFI+mXC7AaEUqBVc2lBQVpAYXkN0EyqNNT12UfDLdxaxaFpUAE2pCa2LTyo5vn5hEW+i3VdN PkmjyPvL6DdY03fvC01PyY8zaw+UI94QqjlrDisHpUH40IUPpC/NB0LwzL2aQOMkzT2NABEB AAG0ME1hcmsgQ2F2ZS1BeWxhbmQgPG1hcmsuY2F2ZS1heWxhbmRAaWxhbmRlLmNvLnVrPokB OAQTAQIAIgUCVAm7PAIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQW8LFb64PMh9f NAgAuc3ObOEY8NbZko72AGrg2tWKdybcMVITxmcor4hb9155o/OWcA4IDbeATR6cfiDL/oxU mcmtXVgPqOwtW3NYAKr5g/FrZZ3uluQ2mtNYAyTFeALy8YF7N3yhs7LOcpbFP7tEbkSzoXNG z8iYMiYtKwttt40WaheWuRs0ZOLbs6yoczZBDhna3Nj0LA3GpeJKlaV03O4umjKJgACP1c/q T2Pkg+FCBHHFP454+waqojHp4OCBo6HyK+8I4wJRa9Z0EFqXIu8lTDYoggeX0Xd6bWeCFHK3 DhD0/Xi/kegSW33unsp8oVcM4kcFxTkpBgj39dB4KwAUznhTJR0zUHf63LkBDQRUCbs8AQgA y7kyevA4bpetM/EjtuqQX4U05MBhEz/2SFkX6IaGtTG2NNw5wbcAfhOIuNNBYbw6ExuaJ3um 2uLseHnudmvN4VSJ5Hfbd8rhqoMmmO71szgT/ZD9MEe2KHzBdmhmhxJdp+zQNivy215j6H27 14mbC2dia7ktwP1rxPIX1OOfQwPuqlkmYPuVwZP19S4EYnCELOrnJ0m56tZLn5Zj+1jZX9Co YbNLMa28qsktYJ4oU4jtn6V79H+/zpERZAHmH40IRXdR3hA+Ye7iC/ZpWzT2VSDlPbGY9Yja Sp7w2347L5G+LLbAfaVoejHlfy/msPeehUcuKjAdBLoEhSPYzzdvEQARAQABiQEfBBgBAgAJ BQJUCbs8AhsMAAoJEFvCxW+uDzIfabYIAJXmBepHJpvCPiMNEQJNJ2ZSzSjhic84LTMWMbJ+ opQgr5cb8SPQyyb508fc8b4uD8ejlF/cdbbBNktp3BXsHlO5BrmcABgxSP8HYYNsX0n9kERv NMToU0oiBuAaX7O/0K9+BW+3+PGMwiu5ml0cwDqljxfVN0dUBZnQ8kZpLsY+WDrIHmQWjtH+ Ir6VauZs5Gp25XLrL6bh/SL8aK0BX6y79m5nhfKI1/6qtzHAjtMAjqy8ChPvOqVVVqmGUzFg KPsrrIoklWcYHXPyMLj9afispPVR8e0tMKvxzFBWzrWX1mzljbBlnV2n8BIwVXWNbgwpHSsj imgcU9TTGC5qd9g= Message-ID: Date: Mon, 25 May 2020 10:02:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200520120709.558a52ba@nas.mammed.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 109.156.104.24 X-SA-Exim-Mail-From: mark.cave-ayland@ilande.co.uk Subject: Re: [RFC PATCH] hw/sparc/sun4m: Use memdev backend for main RAM X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on mail.default.ilande.uk0.bigv.io) Received-SPF: pass client-ip=2001:41c9:1:41f::167; envelope-from=mark.cave-ayland@ilande.co.uk; helo=mail.default.ilande.uk0.bigv.io X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, Artyom Tarasenko Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/05/2020 11:07, Igor Mammedow wrote: > On Thu, 14 May 2020 14:13:11 +0200 > Philippe Mathieu-Daudé wrote: > >> On 5/14/20 12:09 PM, Igor Mammedov wrote: >>> On Sun, 10 May 2020 13:35:05 +0200 >>> Philippe Mathieu-Daudé wrote: >>> >>>> Since commit 82b911aaff3, machine_run_board_init() checks for >>>> ram_memdev_id and consume it. As TYPE_SUN4M_MEMORY is no more >>>> needed, replace it by the generic memdev allocated MemoryRegion >>>> and remove it. This completes commit b2554752b1da7c8f. >>> >>> I don't get justification here. >>> You are removing 'frontend' device model that has little/nothing >>> to do with how backend is instantiated. >>> >>> TYPE_SUN4M_MEMORY is analog to pc-dimm, only for builtin RAM >>> (not really useful but could serve as an example). >> >> I have no idea about the benefits of using memory frontend/backend >> with emulation. Is there documentation and examples? I'm seeing this >> code as a complicated way of doing a simple thing, but I guess I'm >> missing the big picture here. > > Examples are pc-dimm and nv-dimm which thanks to separation easily > reusable across pc/spapr/virt-arm. > > Having frontend is also useful for mgmt purposes, where HMP/QMP > just has to enumerate all RAM devices, otherwise boards would have > to provide a callback to describe their custom mappings. > > But for embed boards with a single blob of RAM nailed down, > having frontend is probably overkill (at least ATM). > So I'm fine with this patch /with amended commit message/ I don't feel too strongly about this, however if there is a standard way of doing things then I would prefer to do that since it makes it easier for me as a maintainer if there are existing (and up-to-date) examples that I can use as a reference. Presumably it also means that if HMP/QMP commands are added in relation to machine RAM then the SPARC machines would get that new functionality automatically... ATB, Mark.