From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43975) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fidUr-0006x6-0T for qemu-devel@nongnu.org; Thu, 26 Jul 2018 06:27:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fidUo-00075Z-18 for qemu-devel@nongnu.org; Thu, 26 Jul 2018 06:27:49 -0400 Received: from mail-it0-x244.google.com ([2607:f8b0:4001:c0b::244]:52510) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fidUn-000754-Rk for qemu-devel@nongnu.org; Thu, 26 Jul 2018 06:27:45 -0400 Received: by mail-it0-x244.google.com with SMTP id d9-v6so1802869itf.2 for ; Thu, 26 Jul 2018 03:27:45 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1532496652-26364-1-git-send-email-hongbo.zhang@linaro.org> <1532496652-26364-2-git-send-email-hongbo.zhang@linaro.org> <20180725095426.f7kv4ftngeje6pkx@kamzik.brq.redhat.com> <20180725114404.6g335n3rfjt23hjc@kamzik.brq.redhat.com> From: Hongbo Zhang Date: Thu, 26 Jul 2018 18:27:44 +0800 Message-ID: Content-Type: text/plain; charset="UTF-8" Subject: Re: [Qemu-devel] [PATCH v2 2/2] hw/arm: Add Arm Enterprise machine type List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Andrew Jones , Radoslaw Biernacki , Ard Biesheuvel , QEMU Developers , Leif Lindholm , qemu-arm , =?UTF-8?B?QWxleCBCZW5uw6ll?= On 25 July 2018 at 20:19, Peter Maydell wrote: > On 25 July 2018 at 12:44, Andrew Jones wrote: >> On Wed, Jul 25, 2018 at 06:46:59PM +0800, Hongbo Zhang wrote: >>> For Armv7, there is one typical platform 'vexpress', but for Armv8, no >> >> Wasn't the vexpress model designed for a specific machine? > > Yes. > >> Namely for >> Arm's simulator? > > No. > >> Is the vexpress model really something typical among >> all the Armv7 platforms? > > No. > > "Vexpress" is a model specifically of a development board > produced by Arm (the versatile express). It's useful if you > want to run code that runs on that devboard, but (as with > most of the devboards we model), it's not necessarily ideal, > because it has all the limitations of the real hardware it's > modelling (in this case the big ones are limited memory, no PCI). > The hardware it models is also quite old now (maybe 7 or 8 years) > and it's not really "typical" of anything. (In the primarily > embedded space where most v7 CPUs are there's not really anything > that could be described as "typical" anyway: everything is > different.) > > For most people who just want to run Linux on an emulated v7 CPU, > I would recommend the "virt" board, for the same reasons I > recommend it for v8 cores. > >>> such typical one, the 'virt' is typically for running workloads, one >>> example is using it under OpenStack. >>> So a 'typical' one for Armv8 is needed for firmware and OS >>> development, similar like 'vexpress' for Armv7. >> >> What is a "typical" Armv8 machine? What will a typical Armv8 machine be in >> two years? >> >> Note, I'm not actually opposed to the current definition (because I don't >> really have one myself). I'm just opposed to hard coding one. > > AIUI the aim here is to provide an emulated platform that is > set up in the way that server-style armv8 machines are > recommended to be set up, so it can be used as a testbed and > demonstration for the firmware/OS software stack. The hope > is that following "best practices" results in a "typical" > machine :-) But the word "typical" is probably not really > very helpful here... Yes the aim is truely like that. Let's forget the word 'typical', a none-english speaker may has his slightly different understanding according to his own language culture... > > I would expect that in the future we'd want this machine type > to evolve with the recommendations for how to build server > platform hardware, which might indeed be different in two years, > since it would be the development platform for writing/testing > the firmware/OS stack for that two-years-time hardware. > > thanks > -- PMM