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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, 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 7C19CC55178 for ; Thu, 29 Oct 2020 10:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E68E20706 for ; Thu, 29 Oct 2020 10:07:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=axis.com header.i=@axis.com header.b="F6eKyWXO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726335AbgJ2KHc (ORCPT ); Thu, 29 Oct 2020 06:07:32 -0400 Received: from smtp2.axis.com ([195.60.68.18]:63878 "EHLO smtp2.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725984AbgJ2KHa (ORCPT ); Thu, 29 Oct 2020 06:07:30 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axis.com; l=1235; q=dns/txt; s=axis-central1; t=1603966049; x=1635502049; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=3dDfRpZrXdi2h9cyLECrD8Pi4UfPbqkN/AeqV38WhpY=; b=F6eKyWXOkleM/r0Mfnqe1Aw5wmvWH6QHiRdzY7j6MONzqEuyLuFXU5jw TX/Y793eUC87QxsyJHVOXR4kFobVJaB0Fg2DzU4KT4tdm+TSqCmDs0Xnx rDHr+HbgfmfYuUJdq6GkUm4GQdJR94b1OYB7YM2+1Pcxk47SoZGSjYIgb /NZVmefHwRO20PNqPhOOio66ucTMev313AYOhZJPlzzZ3YHkUFplYTGoQ YNTg8w0ggZGtrEZjjq74r/1C9Y86vYK1vpdKF6e6Be3R8k0GtoO4NQRt8 6IAQka70ZMHeBcsK9PnGBgzVObce0zcvKdymFjtoXVIvDfGY0zzDlEInN w==; IronPort-SDR: cYyEylfPzxmDd4ZhHRuVfvgvp2Zcdmv3PoASyiieKb4bE8CRzutBYe8oqq+FRwKO3Ew26Z24iA vI+jqeGTsC/njYhc7yudJuhSJESfkNevUfqq8wmigJcb0pxCAWVPEkB5LwAOGNYWTliqxaRB2O HGFaLFoopbJF3DQEl9HjhHyNLrs9wahjlBIrXBkjJThypoheDAjqgVgWt0B7AKrBBca8ULrI8Q eyKe6qnjQvU/NW7gQX9Ejrs2AusAkTchZTY7zMnzJ1Ug954iC0KmSGxDffqLO6wJ7J7kOybGeW HqQ= X-IronPort-AV: E=Sophos;i="5.77,429,1596492000"; d="scan'208";a="14036188" Date: Thu, 29 Oct 2020 11:07:27 +0100 From: Vincent Whitchurch To: Arnd Bergmann CC: Sherry Sun , "Dutt, Sudeep" , dl-linux-imx , "linux-kernel@vger.kernel.org" , "hch@infradead.org" , "kishon@ti.com" , "lorenzo.pieralisi@arm.com" , "gregkh@linuxfoundation.org" , "Dixit, Ashutosh" Subject: Re: [PATCH V3 2/4] misc: vop: do not allocate and reassign the used ring Message-ID: <20201029100727.trbppgbusd5vogpz@axis.com> References: <20201023092650.GB29066@infradead.org> <20201027062802.GC207971@kroah.com> <20201027151106.e4skr6dsbwvo4al6@axis.com> <93bd1c60ea4d910489a7592200856eaf8022ced0.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2020 at 04:50:36PM +0100, Arnd Bergmann wrote: > I think we should try to do something on top of the PCIe endpoint subsystem > to make it work across arbitrary combinations of host and device > implementations, > and provide a superset of what the MIC driver, (out-of-tree) Bluefield endpoint > driver, and the NTB subsystem as well as a couple of others used to do, > each of them tunneling block/network/serial/... over a PCIe link of some > sort, usually with virtio. VOP is not PCIe-specific (as demonstrated by the vop-loopback patches I posted a while ago [1]), and it would be a shame for a replacement to be tied to the PCIe endpoint subsystem. There are many SOCs out there which have multiple Linux-capable processors without cache-coherency between them. VOP is (or should I say was since I guess it's being deleted) the closest we have in mainline to easily get generic virtio (and not just rpmsg) running between these kind of Linux instances. If a new replacement framework were to be PCIe-exclusive then we'd have to invent one more framework for non-PCIe links to do pretty much the same thing. [1] https://lore.kernel.org/lkml/20190403104746.16063-1-vincent.whitchurch@axis.com/