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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 C9ACFC388F7 for ; Sat, 31 Oct 2020 10:05:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A2E42074F for ; Sat, 31 Oct 2020 10:05:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iZG/IQqv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726663AbgJaKF5 (ORCPT ); Sat, 31 Oct 2020 06:05:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:51746 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726484AbgJaKF5 (ORCPT ); Sat, 31 Oct 2020 06:05:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1604138755; h=from:from:reply-to:subject:subject: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=AnjgLhuePwx0jJk40v4DM0roK18yccWOA7FCi5j5z9Y=; b=iZG/IQqvAIeTynrfHEqfXq3l7rCu0bZ6GWMyJpBdMHNpRpIe1/we5Qnp6LeDy+Y3NajmQo QB76syleFRzAuyxlGU9KoymzhorgMxKmy7zsyOiS04ULlrjehI0263JU9XJOoSiCH1OVEZ zeNKRcapIiL1XN4Nz4OcT661sAcrYBU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-542-z9cKa54QMqiCjDV5EtZyuQ-1; Sat, 31 Oct 2020 06:05:51 -0400 X-MC-Unique: z9cKa54QMqiCjDV5EtZyuQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 270381074641; Sat, 31 Oct 2020 10:05:49 +0000 (UTC) Received: from [10.36.112.45] (ovpn-112-45.ams2.redhat.com [10.36.112.45]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4786760C05; Sat, 31 Oct 2020 10:05:46 +0000 (UTC) Subject: Re: mm/memblock: export memblock_{start/end}_of_DRAM To: Christoph Hellwig , Mike Rapoport Cc: Sudarshan Rajagopalan , Mark Rutland , Catalin Marinas , Anshuman Khandual , linux-kernel@vger.kernel.org, Steven Price , Suren Baghdasaryan , Greg Kroah-Hartman , Will Deacon , linux-arm-kernel@lists.infradead.org, Pratik Patel References: <20201030083842.GA4319@kernel.org> <20201031091846.GA30512@infradead.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Sat, 31 Oct 2020 11:05:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20201031091846.GA30512@infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31.10.20 10:18, Christoph Hellwig wrote: > On Fri, Oct 30, 2020 at 10:38:42AM +0200, Mike Rapoport wrote: >> >> What do you mean by "system memory block"? There could be a lot of >> interpretations if you take into account memory hotplug, "mem=" option, >> reserved and firmware memory. >> >> I'd suggest you to describe the entire use case in more detail. Having >> the complete picture would help finding a proper solution. > > I think we need the code for the driver trying to do this as an RFC > submission. Everything else is rather pointless. Sharing RFCs is most probably not what people want when developing advanced hypervisor features :) @Sudarshan, I recommend looking at the slides of the KVM Forum talk from yesterday https://kvmforum2020.sched.com/event/eE40/towards-an-alternative-memory-architecture-joao-martins-oracle?iframe=no It contains a nice summary of the state of art, and how "mem=", devdax, and dax_hmat can be used to tackle the issue in a hypervisor. -- Thanks, David / dhildenb