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 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ECB95C433EF for ; Mon, 17 Jan 2022 14:16:25 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.258186.444360 (Exim 4.92) (envelope-from ) id 1n9Snj-0001RT-Bg; Mon, 17 Jan 2022 14:16:03 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 258186.444360; Mon, 17 Jan 2022 14:16:03 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1n9Snj-0001RM-8Q; Mon, 17 Jan 2022 14:16:03 +0000 Received: by outflank-mailman (input) for mailman id 258186; Mon, 17 Jan 2022 14:16:02 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1n9Sni-0001RG-EV for xen-devel@lists.xenproject.org; Mon, 17 Jan 2022 14:16:02 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1n9Sng-0005Ec-5b; Mon, 17 Jan 2022 14:16:00 +0000 Received: from [202.153.81.7] (helo=[192.168.175.62]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1n9Snf-00044k-In; Mon, 17 Jan 2022 14:16:00 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:To:Subject:MIME-Version:Date:Message-ID; bh=3uNZUHo9f86iIDSTgNlg44jVZ3jVx/Z5w5iXWJKkRj4=; b=o4fa7nmGwFFdGTrkFBf1ben6Sz ao9VJVydHntdUezHETp6p34y45r9luH7R+y2+7dew37P6q/ikdK0NrGX5BgIZL1J0ECvslUrXaGgG FcxnNW/ahdBzgSL5qVfxbgARuFh/G9GR/LSF/2g3fTIf+Bxda48oc3z7CqjMni8hs724=; Message-ID: <2a1a0dd5-b8a7-8072-2961-b1fbe9ec746a@xen.org> Date: Mon, 17 Jan 2022 18:15:53 +0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.4.1 Subject: Re: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2 To: Dongjiu Geng , sstabellini@kernel.org, Volodymyr_Babchuk@epam.com, bertrand.marquis@arm.com, xen-devel@lists.xenproject.org References: <20220117064003.3367188-1-gengdongjiu1@gmail.com> From: Julien Grall In-Reply-To: <20220117064003.3367188-1-gengdongjiu1@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 17/01/2022 10:40, Dongjiu Geng wrote: > It turns out that QEMU has been supporting GICv2 virtualization since > v3.1.0. So remove the dependencies on GICv3. Technically, the current form of CONFIG_QEMU allows the same binary to boot on QEMU with GICv2 or GICv3. > If we want to use GICv3, > we can select the QEMU_LEGACY configuration. AFAIK, GICv3 is not a legacy feature... So it feels a bit odd to name it like that (see more below). > > Signed-off-by: Dongjiu Geng > --- > xen/arch/arm/platforms/Kconfig | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/xen/arch/arm/platforms/Kconfig b/xen/arch/arm/platforms/Kconfig > index c93a6b2756..41e82a42ee 100644 > --- a/xen/arch/arm/platforms/Kconfig > +++ b/xen/arch/arm/platforms/Kconfig > @@ -13,7 +13,15 @@ config ALL_PLAT > automatically select any of the related drivers. > > config QEMU > - bool "QEMU aarch virt machine support" > + bool "QEMU aarch virt machine support >= v3.1.0" This is a bit misleading. A user may select this thinking that this will select GICv3. However, this will not. This also raises the question of what is the default GIC version in QEMU (i.e. if you don't pass anything on the command line)? If this is GICv3, then I am afraid that this patch would be a no-go for me. Looking at overall discussion, you seem to push the patch only to allow building a tiny Xen for QEMU and the new vGIC. The default Xen (i.e. make defconfig) will also work on QEMU. Given that the new vGIC is a still in development, I am seriously considering to say that if you want to try it then you have to use the default configuration. @Dongjiu, is there any reason why you want to use the tiny QEMU config rather than the default configuration? @Bertrand, @Stefano, what do you think? Cheers, -- Julien Grall