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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 49A9CC433FE for ; Thu, 10 Dec 2020 11:58:15 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id E509123D5A for ; Thu, 10 Dec 2020 11:58:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E509123D5A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.49145.86908 (Exim 4.92) (envelope-from ) id 1knKa4-0002oC-T8; Thu, 10 Dec 2020 11:57:56 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 49145.86908; Thu, 10 Dec 2020 11:57:56 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1knKa4-0002o5-PJ; Thu, 10 Dec 2020 11:57:56 +0000 Received: by outflank-mailman (input) for mailman id 49145; Thu, 10 Dec 2020 11:57:55 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1knKa3-0002o0-Mk for xen-devel@lists.xenproject.org; Thu, 10 Dec 2020 11:57:55 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1knKa1-0005eh-Nf; Thu, 10 Dec 2020 11:57:53 +0000 Received: from [54.239.6.185] (helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1knKa1-0001w6-Dr; Thu, 10 Dec 2020 11:57:53 +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: MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=vrBLsUjlzYoDlkXVsPb2wZLmKVxCUpiso65HZWimxZ8=; b=ueG75IqjVUNWvJZ9NnldyJFlVn 2UO69DhkmXUjO575Tuxy2S/6bTVGFj4yreOSwALR7cnx+KOH8a3Ng0iwz0cfjHKKv4IT2rD6nJeed i+slXrJPLY4BarhMrRQpwj8TPuMmiAkDvqUvl8GGxaBbeslt4JUKwEMx4g5aNoCYEYGk=; Subject: Re: [PATCH RFC 0/3] xen: add hypfs per-domain abi-features To: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= , xen-devel@lists.xenproject.org Cc: paul@xen.org, Andrew Cooper , George Dunlap , Ian Jackson , Jan Beulich , Stefano Stabellini , Wei Liu References: <20201209161618.309-1-jgross@suse.com> From: Julien Grall Message-ID: <8122851a-e674-4283-d82a-9cc99425d66c@xen.org> Date: Thu, 10 Dec 2020 11:57:51 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit On 10/12/2020 07:49, Jürgen Groß wrote: > On 09.12.20 17:24, Julien Grall wrote: >> Hi, >> >> On 09/12/2020 16:16, Juergen Gross wrote: >>> This small series is meant as an example how to add further dynamical >>> directories to hypfs. It can be used to replace Paul's current approach >>> to specify ABI-features via domain create flags and replace those by >>> hypfs nodes. >> >> This can only work if all the ABI-features are not required at the >> time of creating the domain. > > Yes. In case there is some further initialization needed this has to be > done later depending on the setting. We used to allocate vCPUs after the domain has been created. But this ended up in a can of worms because this requires a careful ordering of the hypercalls. So I would rather like to avoid introducing similar operation again... > >> Those features should also be set only once. Furthermore, HYPFS is so >> far meant to be optional. > > "set once" isn't the point. They should not be able to change after the > domain has been started, and that is covered. That really depends on the flag. Imagine there are dependencies between flags or memory needs to be allocated. > >> >> So it feels to me Paul's approach is leaner and better for the >> ABI-features purpose. > > Depends. > > My approach doesn't need any tools side changes after first > implementation when adding new abi-features. And it isn't expanding an > unstable interface. > > In the end this is the reason I marked this series as RFC. If using > flags is preferred, fine. I prefer the flag version. Let see what other thinks. Cheers, --- Julien Grall