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 E8B2BC433EF for ; Wed, 13 Apr 2022 09:51:59 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.304009.518503 (Exim 4.92) (envelope-from ) id 1neZf4-00012I-HJ; Wed, 13 Apr 2022 09:51:42 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 304009.518503; Wed, 13 Apr 2022 09:51:42 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1neZf4-00012B-DR; Wed, 13 Apr 2022 09:51:42 +0000 Received: by outflank-mailman (input) for mailman id 304009; Wed, 13 Apr 2022 09:51:41 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1neZf3-000125-BV for xen-devel@lists.xenproject.org; Wed, 13 Apr 2022 09:51:41 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1neZf2-00077i-Ba; Wed, 13 Apr 2022 09:51:40 +0000 Received: from 54-240-197-227.amazon.com ([54.240.197.227] helo=[10.7.236.29]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1neZf2-0006ji-5C; Wed, 13 Apr 2022 09:51:40 +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:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=0JT6rkxBRasIQr52TMS506loTlmaQnKyglnW//h1bvo=; b=PcNuxt+3Gs8Y1LrBppE0CCT819 XZXR/Trn0NTJbSZirC7kXSH5Fmrl2jqsMdwRaPxO2EOqcPsnWgjd6WM+lHqM3/JZrwJGr/B9ZVYbd KvgAzTyrTtKIfY4NM96E9hFrLqjmYA8XQIopuf2ai8cUqqHkoijAt7lkTV73XGSVC8PY=; Message-ID: <77630661-9ce1-9dff-b050-4676f4845ce7@xen.org> Date: Wed, 13 Apr 2022 10:51:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] xen/evtchn: Add design for static event channel signaling for domUs.. To: Stefano Stabellini Cc: Rahul Singh , xen-devel@lists.xenproject.org, bertrand.marquis@arm.com, Andrew Cooper , George Dunlap , Jan Beulich , Wei Liu References: <4836304496e6fbbea41348ed8cc9fcf6b0f3e893.1648049827.git.rahul.singh@arm.com> <0210f3c6-0f06-4ff5-9f66-8410fd540171@xen.org> From: Julien Grall In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Stefano, On 12/04/2022 21:39, Stefano Stabellini wrote: >>> I should mention that it would be also possible to use sub-nodes to >>> express this information: >>> >>> 2) >>> domU1: domU1 { >>> ... >>> /* one sub-node per local event channel */ >>> ec1: evtchn@a { >>> compatible = "xen,evtchn-v1"; >>> /* local-evtchn link-to-foreign-evtchn */ >>> xen,evtchn = <0xa &ec3> >>> }; >>> ec2: evtchn@c { >>> compatible = "xen,evtchn-v1"; >>> xen,evtchn = <0xc &ec4> >>> }; >>> }; >>> >>> domU2: domU2 { >>> ... >>> ec3: evtchn@b { >>> compatible = "xen,evtchn-v1"; >>> xen,evtchn = <0xb &ec1> >>> }; >>> ec4: evtchn@d { >>> compatible = "xen,evtchn-v1"; >>> xen,evtchn = <0xd &ec2> >>> }; >>> }; >>> }; >> >> As for 1), you could combine all the ports in one node. > > I thought about it but I couldn't come up with a way to do that which > retains the simplicity of this example. The problem is that in device > tree you can only link to nodes, not to individual properties. So I > think we would have to have separate nodes for each event channel so > that we could separately link to them. Ah yes. I overlooked it when making the suggestion. That said, I think my point in my previous e-mail stands. If this is too verbose, then we could provide macro to generate the event channel node. > > Otherwise, we would have to add the foreign event channel number in > addition to the link to be able to distinguish them. And that would > result in duplicated information. E.g.: This is not indeed not great. > > domU1: domU1 { > ... > /* one sub-node per local event channel */ > ec1: evtchn@a { > compatible = "xen,evtchn-v1"; > /* local-evtchn link-to-foreign foreign-evtchn */ > xen,evtchn = <0xa &ec2 0xa 0xc &ec2 0xd> > }; > }; > > domU2: domU2 { > ... > ec2: evtchn@b { > compatible = "xen,evtchn-v1"; > xen,evtchn = <0xb &ec1 0xa 0xd &ec1 0xc> > }; > }; Cheers, -- Julien Grall