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 6CCC9C433B4 for ; Thu, 8 Apr 2021 05:56:34 +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 EBE4461165 for ; Thu, 8 Apr 2021 05:56:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EBE4461165 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com 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.107026.204565 (Exim 4.92) (envelope-from ) id 1lUNeE-0007hN-Vn; Thu, 08 Apr 2021 05:56:10 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 107026.204565; Thu, 08 Apr 2021 05:56:10 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lUNeE-0007hG-SP; Thu, 08 Apr 2021 05:56:10 +0000 Received: by outflank-mailman (input) for mailman id 107026; Thu, 08 Apr 2021 05:56:10 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lUNeE-0007hB-BV for xen-devel@lists.xenproject.org; Thu, 08 Apr 2021 05:56:10 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 601408db-92cf-4cba-baea-92d30bdfbfc4; Thu, 08 Apr 2021 05:56:08 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 6F3BDAFE8; Thu, 8 Apr 2021 05:56:07 +0000 (UTC) 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" X-Inumbo-ID: 601408db-92cf-4cba-baea-92d30bdfbfc4 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1617861367; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6jSmWBxiyMH5VNDpuGT7S8hLoJSPm8i2aXRLOgYL65E=; b=TekRN2Bsc8CpLLOLuSQAQkSLJt5dr4wjZmRhzr38lkmhabEhcSPVg1jz8Pu9z6ueNgErse tCOUqER3L92oyLeu+kVCGS5fEhpxSFCXMpdUlXgsMVV4Zn5fpYZlupjXURvcwJTPZLwRYp E6Jhjd4dOg/jlF7BbAGTDu40EoPTLu8= Subject: Re: [PATCH 0/2] Introducing hyperlaunch capability design (formerly: DomB mode of dom0less) To: Christopher Clark Cc: "Daniel P. Smith" , Andrew Cooper , Stefano Stabellini , Julien Grall , Julien Grall , iwj@xenproject.org, Wei Liu , George Dunlap , Rich Persaud , Bertrand Marquis , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , luca.fancellu@arm.com, paul@xen.org, Adam Schwalm , xen-devel References: <20210316031814.10311-1-dpsmith@apertussolutions.com> <6314f50f-b4fc-e472-4c9a-3591e168d2c3@apertussolutions.com> From: Jan Beulich Message-ID: <2651d116-7c44-261e-8561-c9b3b5a4aab8@suse.com> Date: Thu, 8 Apr 2021 07:56:02 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 07.04.2021 21:23, Christopher Clark wrote: > On Tue, Mar 30, 2021 at 7:31 AM Jan Beulich wrote: >> >> On 16.03.2021 04:56, Daniel P. Smith wrote: >>> To assist in reading, please find attached rendered copies of the design >>> docs. It should be noted that due to poor rendering by pandoc, we forced >>> the tables to stay as ASCII tables in the patches whereas the attached >>> docs have the tables rendered properly by rst2pdf. >> >> In section 3.6 I found "As a result, on x86 the hyperlaunch capability does >> not rely on nor preclude any specific BIOS boot protocol, i.e legacy BIOS >> boot or UEFI boot. The only requirement is that the boot loader supports >> the Multiboot2 (MB2) protocol." I'm afraid the two sentences contradict >> one another, as UEFI on its own doesn't provide MB2 functionality. It is >> my understanding that you don't require this anyway - what you need is a >> way to load modules beyond just Dom0 kernel and an initrd. > > Thanks - we'll amend the doc. Given the already sizeable scope of the > project, our current approach for host UEFI is to recommend use of > GRUB.efi to load Xen and the initial domains via the multiboot2 method. > >> I'm also struggling to see how you mean to associate the (MB2) modules >> passed to Xen with the individual functions. I.e. I don't see how it will >> be ensure that the embedded mb-index is in sync with the order or modules >> actually supplied. > > To make sure I'm following the concern raised here, my understanding is: > > - the multiboot module list is ordered and stable, so that the order > that the bootloader provides the modules in is the same order in which > Xen receives them, in the multiboot data structure, so the modules can > be referenced by an index into that list In a separate context (parallel ongoing discussion under "multiboot2 and module2 boot issues via GRUB2") Andrew raised the (imo valid) point of this getting the more fragile the more modules there are. > - for a given Launch Control Module file (expressed in a Device Tree, as > described in our second design document), the provided multiboot > modules will need to match, both in type (kernel, ramdisk, microcode, > xsm policy) and order "Need to match" meaning what? You don't clarify how boot loader config and device tree blob are meant to be kept in sync. > - we think that at some point the LCM will end up being dynamically > generated by an enlightened bootloader, assembling it from the > bootloader config file, which will list the modules and their types > >> As to modules - iirc there are placement restrictions by at least some >> boot loaders (below 4Gb). If that's correct, do you have any thoughts >> towards dealing with the limited space available to hold these modules? >> I've seem systems with lots of memory, but with as little as just 1Gb >> below the 4Gb boundary. > > At this point, I don't think that we'll break anything that currently > works, and that hardware or platform limitations can always constrain > what is deployable. I'm not concerned of you breaking anything. I merely raised a possible scalability issue of your current proposal. Jan