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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 8E669C83001 for ; Tue, 28 Apr 2020 16:39:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 66DB7208FE for ; Tue, 28 Apr 2020 16:39:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588091967; bh=8RpWHwtl4RZqT1ZbuFdwUYbYF9iOnIhy5wLRan7Ele0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=wEO1LolsZ/xcHmiKiWQfl0YYlP+OWkhm6qUphoh5DJnfXVUlZqFOQdJjupUF8t92z kf7hJv6fzhZf4vq3MSTWbcAqes1oKEXsQGSXOEMhhGp8OlCDznZaSkV3Rnx3yP/bGK ex6MwAz4G9fwbPYF1eCUrvEeO4o0hbDc1ZH286AE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728319AbgD1Qj1 (ORCPT ); Tue, 28 Apr 2020 12:39:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:49412 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728106AbgD1Qj0 (ORCPT ); Tue, 28 Apr 2020 12:39:26 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F2E12206D6; Tue, 28 Apr 2020 16:39:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588091966; bh=8RpWHwtl4RZqT1ZbuFdwUYbYF9iOnIhy5wLRan7Ele0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=C3O5HAnG/zI1EGbjpMSLFe4PPxjQXabbbGgb9/ZXUha0QkwEz2h9CJvqtGWWD//7q UqNTUwFQ9bNLrNTP5PiiThvSwqZxl2lJG1893SB4WE+ax/9unkmYml66+Suxe/7MgL n0o8XYwfyFRJMUv5hbxlnekwyonUpKdOGUuo1o2c= Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1jTTGW-007QwJ-AY; Tue, 28 Apr 2020 17:39:24 +0100 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 28 Apr 2020 17:39:24 +0100 From: Marc Zyngier To: Michael Mrozek Cc: Lukas Straub , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, kernel@pyra-handheld.com Subject: Re: Against removing aarch32 kvm host support In-Reply-To: <9c67a3722611d1ec9fe1e8a1fbe65956b32147c3.camel@openpandora.org> References: <20200428143850.4c8cbd2a@luklap> <916b6072a4a2688745a5e3f75c1c8c01@misterjones.org> <9c67a3722611d1ec9fe1e8a1fbe65956b32147c3.camel@openpandora.org> User-Agent: Roundcube Webmail/1.4.3 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: EvilDragon@openpandora.org, lukasstraub2@web.de, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, kernel@pyra-handheld.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Michael, On 2020-04-28 15:26, Michael Mrozek wrote: > Am Dienstag, den 28.04.2020, 14:30 +0100 schrieb Marc Zyngier: > > Hi, > > well, the PCBs are currently in production, the cases are already here > (coating > is currently being delayed as the company has closed down due to Corona > right > now), so the first 500 units would be ready to be shipped in around 2 - > 3 months > at latest. > > The non-existance problem would therefore be solved then. And then? Are these 500 machines going to be instantly turned into production KVM hosts? Over 7 years, we have identified at most *four* users. Four users over a few billion 32bit ARM devices running Linux. What are the odds that you will actually use KVM in any significant way? None whatsoever. > So far, AFAIK, the Letux team has tried their best to get as close to > possible > to mainline kernel and support as many classic devices (OMAP3 and OMAP4 > devices > as well), so removing 32bit support from mainline would surely be a > step back > for a lot of older devices as well. Read the above. No users. Which means that KVM/arm is untested and is just bit-rotting. It is also incomplete and nobody is interested in putting the required effort to help it moving forward. Hell, the whole ARM port is now on life support, and you worry about KVM? > I know we have to accept the decision, but so far, I've known Linux to > support > as many older devices as possible as well - removing KVM Host 32bit > support > would be a step back here. Linux is known to support as many *useful* devices and features as possible. KVM isn't one of them. > Is there a specific reason for that? Please read the threads on the subject. > Is it too complex to maintain alongside the aarch64 KVM Host? It certainly gets in the way of making significant changes to the arm64 port. And as I said, feel free to revive the port anytime. The code is still there, the documentation available, and you're lucky enough to have one of the few machines capable of virtualization. If all of a sudden you end-up finding the killer use case for KVM/arm, I'll applaud its return. In the meantime, the arm64 will be able to move at a much faster pace. As it turns out, it has actual users. Thanks, M. > >> Hi Lukas, >> >> Thanks for your email. >> >> On 2020-04-28 13:38, Lukas Straub wrote: >> > Hello Everyone, >> > As a preorder of the Pyra handheld, (OMAP5 SoC with 2x cortex-a15 arm >> > cores) >> > I'm against removing KVM host support for aarch32. I'm probably going >> > to use >> > this device for more than 5 years and thus the latest lts-kernel is no >> > option >> > for me. >> >> So let me spell it out. You are against the removal of a feature that >> you don't >> use yet, that you may of may not use on a device that doesn't exist >> yet, >> which >> you may or may not still be using by the time 5.4/5.6 aren't supported >> anymore. >> You don't seem to have the strongest case, I'm afraid. >> >> But nothing is lost! The code is still in the git tree, ou can always >> revert >> the removal patches and revive the port if you are so inclined. It >> will >> just need >> to be stand-alone, and not depend on the arm64 code, which is now >> evolving its own >> separate way. >> >> Cheers, >> >> M. > -- > Mit freundlichen Grüßen, > > Michael Mrozek > > ----------------------- > OpenPandora GmbH > Geschäftsführer: Michael Mrozek > > Schäffbräustr. 11 > 85049 Ingolstadt > Deutschland > Tel.: 0841 / 990 5548 > http://www.openpandora.de/ > HRB 4879, Amtsgericht Ingolstadt > ----------------------- > eMail: mrozek@openpandora.org -- Jazz is not dead. It just smells funny...