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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C3ACC43334 for ; Wed, 6 Jul 2022 21:30:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234391AbiGFVaw (ORCPT ); Wed, 6 Jul 2022 17:30:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234627AbiGFVas (ORCPT ); Wed, 6 Jul 2022 17:30:48 -0400 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E3412A94F; Wed, 6 Jul 2022 14:30:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=8YduW0eS5FyJqaOqaP8Ime9Kxv0Nz0ax91qwOz8aVq0=; b=tJ8pa1OCY41/griklmW+EWfOVD GWRX3NjEHhYKoa1dirAXu9tcLaN+qpf0nzpSUt6AE2hSTAMaGkgPgv4NcYCGYPyn5+QpenS+wTnVf dzwHgdTgxI67I3CmK0cMnjTb734bjxbjYx7DQA9orlsLZwJnT7/WMP2dzbiZ7YbAQzYQu/y+kd36E NWKd/LUDPN2BcSU2j0kYeELLqOgQTg66ewIFq/UnLnPvN5w4UmYxGdTvEJEsZFKMhHTjiXUcAJU+a 56SmKOp2xezp85myJotIUFWF91GMeRTiTwry5HfRHn7/M0IWeMCxtQww2OKOWXkI2zuBZnUl0FPwc DaJoW4Qg==; Received: from s0106ac1f6bb1ecac.cg.shawcable.net ([70.73.163.230] helo=[192.168.11.155]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1o9CbT-008LWu-KY; Wed, 06 Jul 2022 15:30:36 -0600 Message-ID: Date: Wed, 6 Jul 2022 15:30:30 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Content-Language: en-US To: Greg Kroah-Hartman , Christoph Hellwig Cc: Jason Gunthorpe , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Dan Williams , =?UTF-8?Q?Christian_K=c3=b6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Bjorn Helgaas References: <20220705161240.GB13721@lst.de> <20220705164315.GB14484@lst.de> <20220705165039.GB14566@lst.de> <1bd43ef7-0403-bd25-087c-d54d5af677e4@deltatee.com> <20220706065127.GA27132@lst.de> From: Logan Gunthorpe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 70.73.163.230 X-SA-Exim-Rcpt-To: gregkh@linuxfoundation.org, hch@lst.de, jgg@ziepe.ca, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, sbates@raithlin.com, dan.j.williams@intel.com, christian.koenig@amd.com, jhubbard@nvidia.com, ddutile@redhat.com, willy@infradead.org, daniel.vetter@ffwll.ch, dave.b.minturn@intel.com, jason@jlekstrand.net, dave.hansen@linux.intel.com, jianxin.xiong@intel.com, helgaas@kernel.org, ira.weiny@intel.com, robin.murphy@arm.com, martin.oliveira@eideticom.com, ckulkarnilinux@gmail.com, rcampbell@nvidia.com, bhelgaas@google.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2022-07-06 01:04, Greg Kroah-Hartman wrote: > On Wed, Jul 06, 2022 at 08:51:27AM +0200, Christoph Hellwig wrote: >> On Tue, Jul 05, 2022 at 12:16:45PM -0600, Logan Gunthorpe wrote: >>> The current version does it through a char device, but that requires >>> creating a simple_fs and anon_inode for teardown on driver removal, plus >>> a bunch of hooks through the driver that exposes it (NVMe, in this case) >>> to set this all up. >>> >>> Christoph is suggesting a sysfs interface which could potentially avoid >>> the anon_inode and all of the extra hooks. It has some significant >>> benefits and maybe some small downsides, but I wouldn't describe it as >>> horrid. >> >> Yeah, I don't think is is horrible, it fits in with the resource files >> for the BARs, and solves a lot of problems. Greg, can you explain >> what would be so bad about it? > > As you mention, you will have to pass different things down into sysfs > in order for that to be possible. If it matches the resource files like > we currently have today, that might not be that bad, but it still feels > odd to me. Let's see an implementation and a Documentation/ABI/ entry > first though. I'll work something up in the coming weeks. Thanks, Logan