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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 05CB7C433E6 for ; Wed, 27 Jan 2021 20:19:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 60F5761488 for ; Wed, 27 Jan 2021 20:19:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 60F5761488 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57398 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l4rHe-0008Hp-9x for qemu-devel@archiver.kernel.org; Wed, 27 Jan 2021 15:19:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:58962) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l4rGw-0007r7-6L for qemu-devel@nongnu.org; Wed, 27 Jan 2021 15:18:38 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:49386) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l4rGu-0001b1-1X for qemu-devel@nongnu.org; Wed, 27 Jan 2021 15:18:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611778714; 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=E3zwjOG+tRC7TxZSYSwG21HhHcFl5gkGV8dOowLpcFs=; b=KCWDZYTPjxTC9FWQCZGuqMTDo32z+zMnDsvyLfI34Bs1TqeEjR31ecgcNac6ravw2Y/r3W emdlQUNS7OV/FhkeIh8mWnKEx5vUcfkM99XFVNL7Hu7QgiXyJO8mYOYiI9mwEA6uST6K23 n0WTTh5E5T7WhqD6D011HiJcJTA02Ho= 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-144-aoBN9Pm4Oa28dwzPxav3Zg-1; Wed, 27 Jan 2021 15:18:32 -0500 X-MC-Unique: aoBN9Pm4Oa28dwzPxav3Zg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6198E1005513; Wed, 27 Jan 2021 20:18:31 +0000 (UTC) Received: from localhost (unknown [10.40.208.33]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1A78360864; Wed, 27 Jan 2021 20:18:26 +0000 (UTC) Date: Wed, 27 Jan 2021 21:18:24 +0100 From: Igor Mammedov To: Ben Widawsky Subject: Re: Handling multiple inheritance [for CXL] Message-ID: <20210127211824.4d64b45d@redhat.com> In-Reply-To: <20210126213013.6v24im4sler3q3am@mail.bwidawsk.net> References: <20210126213013.6v24im4sler3q3am@mail.bwidawsk.net> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=imammedo@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.308, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Markus Armbruster , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Xiao Guangrong Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 26 Jan 2021 13:33:52 -0800 Ben Widawsky wrote: > I'm working on CXL 2.0 type 3 memory devices [1]. In short, these are PCIe devices > that have persistent memory on them. As such, it would be nice to inherit from > both a PCI_DEVICE class as well as an NVDIMM device class. > > Truth be told, using TYPE_MEMORY_DEVICE as the interface does provide most of > what I need. could you be more specific on what you need from it? >I'm wondering what the best way to handle this is. Currently, the > only thing NVDIMM class provides is write/read_label_data, this is driven by > _DSM. For CXL, the mechanism to read/write the equivalent area is not done via > _DSM, but done directly via a mailbox interface. However, the intent is the > same, and so utilizing similar code seems ideal. > > If there's a desire to unify these code paths, I'd need something like multiple > inheritance. I'm looking for some feedback here on how to do it. > > Thanks. > Ben > > [1]: https://lore.kernel.org/qemu-devel/20210105165323.783725-1-ben.widawsky@intel.com/ >