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=-18.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 E960BC07E95 for ; Sun, 11 Jul 2021 01:00:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD57F6135E for ; Sun, 11 Jul 2021 01:00:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231286AbhGKBC6 (ORCPT ); Sat, 10 Jul 2021 21:02:58 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60029 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229771AbhGKBCz (ORCPT ); Sat, 10 Jul 2021 21:02:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625965209; h=from:from:reply-to: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=ib12whr0TI5EJxJbfZnuqGZ4brCYijHN/MYKHEGojws=; b=f6sE2yoZf0s9vg5ks+i/1TAURpbq16j0dvHsz7zBIJFYy/nIsx/ztvIjkXw+5m+c5zZYyN dzaSbQ78qr1tzxNedOs4cIZ0RxD/mNJCD1/SeJGCHEhwkn9g5r+DojERvEyIF0LoRTENGY X8OrDON5O9DtxLg6xYPkBecmuu5v4lk= 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-567-MyP71OAEMMejluC2ZkzmeQ-1; Sat, 10 Jul 2021 21:00:07 -0400 X-MC-Unique: MyP71OAEMMejluC2ZkzmeQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 394CF18414A0; Sun, 11 Jul 2021 01:00:06 +0000 (UTC) Received: from [10.64.54.119] (vpn2-54-119.bne.redhat.com [10.64.54.119]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B20DF100F49F; Sun, 11 Jul 2021 01:00:02 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH v5] Documentation, dt, numa: Add note to empty NUMA node From: Gavin Shan To: Rob Herring Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, rdunlap@infradead.org, drjones@redhat.com, shan.gavin@gmail.com References: <20210628093411.88805-1-gshan@redhat.com> <20210701172527.GA2567910@robh.at.kernel.org> <1c43cd39-7bf6-b99c-36ec-798b81b1aba1@redhat.com> Message-ID: <6168ef6a-53a0-403c-0412-0ec3c0546c61@redhat.com> Date: Sun, 11 Jul 2021 10:59:58 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <1c43cd39-7bf6-b99c-36ec-798b81b1aba1@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rob, On 7/2/21 10:02 AM, Gavin Shan wrote: > On 7/2/21 3:25 AM, Rob Herring wrote: >> On Mon, Jun 28, 2021 at 05:34:11PM +0800, Gavin Shan wrote: >>> The empty memory nodes, where no memory resides in, are allowed. >>> For these empty memory nodes, the 'len' of 'reg' property is zero. >>> The NUMA node IDs are still valid and parsed, but memory may be >>> added to them through hotplug afterwards. I finds difficulty to >>> get where it's properly documented. >> >> This is already in use? If so, what platform(s)? >> > > It's not used yet, but will be used by QEMU once this patch is merged. > In QEMU, ARM64 could have multiple empty memory nodes. The corresponding > NUMA ID and distance map are still valid because memory may be added into > these empty memory nodes in future. > > For the QEMU case, the names of empty memory nodes are the biggest concern. > According to device-tree specification, the name follows the format of > 'memory@unit-address' and the 'unit-address' is equivalent to 'base-address'. > However, the 'base-address' should be invalid one. In current QEMU implementation, > the valid 'base-address' and 'unit-address' are provided to these empty > memory nodes. Another issue in QEMU is trying to populate two empty memory > nodes, which have same names. This leads to failure of device-tree population > because of the duplicated memory node names, blocking VM from booting. > >>> So lets add a section for empty memory nodes in NUMA binding >>> document. Also, the 'unit-address', equivalent to 'base-address' >>> in the 'reg' property of these empty memory nodes is suggested to >>> be the summation of highest memory address plus the NUMA node ID. >> >> What purpose does this serve? The kernel won't do anything with it other >> than validate the numa-node-id range. >> > > As mentioned above, the point is to have dummy, invalid and non-overlapped > 'base-address' and 'unit-address' for these empty memory nodes, to avoid > duplicated memory node names in devcie-tree. > >>> >>> Signed-off-by: Gavin Shan >>> --- >>> v5: Separate section for empty memory node >>> --- >>>   Documentation/devicetree/bindings/numa.txt | 61 +++++++++++++++++++++- >>>   1 file changed, 60 insertions(+), 1 deletion(-) >>> >>> diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt >>> index 21b35053ca5a..230c734af948 100644 >>> --- a/Documentation/devicetree/bindings/numa.txt >>> +++ b/Documentation/devicetree/bindings/numa.txt >>> @@ -103,7 +103,66 @@ Example: >>>           }; >>>   ============================================================================== >>> -4 - Example dts >>> +4 - Empty memory nodes >>> +============================================================================== >>> + >>> +Empty memory nodes, which no memory resides in, are allowed. The 'length' >>> +field of the 'reg' property is zero, but the 'base-address' is a dummy >>> +address and invalid. The 'base-address' could be the summation of highest >>> +memory address plus the NUMA node ID. However, the NUMA node IDs and >>> +distance maps are still valid and memory may be added into them through >>> +hotplug afterwards. >>> + >>> +Example: >>> + >>> +    memory@0 { >>> +        device_type = "memory"; >>> +        reg = <0x0 0x0 0x0 0x80000000>; >>> +        numa-node-id = <0>; >>> +    }; >>> + >>> +    memory@0x80000000 { >> >> unit-address should not have '0x'. >> > > Ok. Lets fix it in v6 after it's agreed to add the section into the > NUMA binding document. Actually, the '0x' is copied from the existing > example in same document. After this patch is finalized, I will post > separate patch to fix all wrong formats in same document as well. > I posted v6 just now, where '0x' in 'unit-address' is dropped. After this is merged, I will post followup patch to remove '0x' in 'unit-address' for existing examples. Thanks, Gavin >>> +        device_type = "memory"; >>> +        reg = <0x0 0x80000000 0x0 0x80000000>; >>> +        numa-node-id = <1>; >>> +    }; >>> + >>> +    /* Empty memory node */ >>> +    memory@0x100000002 { >>> +        device_type = "memory"; >>> +        reg = <0x1 0x2 0x0 0x0>; >>> +        numa-node-id = <2>; >>> +    }; >>> + >>> +    /* Empty memory node */ >>> +    memory@0x100000003 { >>> +        device_type = "memory"; >>> +        reg = <0x1 0x3 0x0 0x0>; >>> +        numa-node-id = <3>; >>> +    }; >>> + >>> +    distance-map { >>> +        compatible = "numa-distance-map-v1"; >>> +        distance-matrix = <0 0  10>, >>> +                  <0 1  20>, >>> +                  <0 2  40>, >>> +                  <0 3  20>, >>> +                  <1 0  20>, >>> +                  <1 1  10>, >>> +                  <1 2  20>, >>> +                  <1 3  40>, >>> +                  <2 0  40>, >>> +                  <2 1  20>, >>> +                  <2 2  10>, >>> +                  <2 3  20>, >>> +                  <3 0  20>, >>> +                  <3 1  40>, >>> +                  <3 2  20>, >>> +                  <3 3  10>; >>> +    }; >>> + >>> +============================================================================== >>> +5 - Example dts >>>   ============================================================================== >>>   Dual socket system consists of 2 boards connected through ccn bus and >>> --