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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 83524C433ED for ; Tue, 13 Apr 2021 07:32:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F06E613B1 for ; Tue, 13 Apr 2021 07:32:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239664AbhDMHdF (ORCPT ); Tue, 13 Apr 2021 03:33:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:35414 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239240AbhDMHdD (ORCPT ); Tue, 13 Apr 2021 03:33:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0C3F7613B1; Tue, 13 Apr 2021 07:32:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618299163; bh=0E4NDVSsgn4e8nD4chZqJrT6BZ9xAxdiPvSP07EJB1Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BeWpHeg3WSvgeOTR/YWiYX610rvkQS+2lfuALZtwCMU+7BjTSnqez876hmLtLkPUI UhX7RDpc1k1TzCpQEGs5MFeMG1I+RcwWTiR4m4ISr3YjXMADpR7gqUEcE9vbYU9foL n5e3Z92m8SpIqzuCpJfknrXi0bs3t0oJRNsgHbwuEclQyGTl/nUaho3fKbY8/CPOFX /DTw+JBzybhPlohaD3eD0rG7+AGKTEwLXP25nXpDD8Pu1MRAgtQiLE3zmKdI1uRHcv G4vJLFQzxl2MYiNPjXDsD/TQc5ILcR6H8+21WeWG6cgjeE6IZhi7z3WIjvddBAnOqy HcI4pRu3CVIcw== Date: Tue, 13 Apr 2021 10:32:39 +0300 From: Leon Romanovsky To: Niklas Schnelle Cc: Narendra K , Viktor Mihajlovski , Stefan Raspl , Peter Oberparleiter , linux-netdev@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH 0/1] Use of =?utf-8?B?L3N5cy9i?= =?utf-8?B?dXMvcGNpL2RldmljZXMv4oCmL2luZGV4?= for non-SMBIOS platforms Message-ID: References: <20210412135905.1434249-1-schnelle@linux.ibm.com> <88c62c2789d5798338736308672867f30d617794.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <88c62c2789d5798338736308672867f30d617794.camel@linux.ibm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 13, 2021 at 08:57:19AM +0200, Niklas Schnelle wrote: > On Tue, 2021-04-13 at 08:39 +0300, Leon Romanovsky wrote: > > On Mon, Apr 12, 2021 at 03:59:04PM +0200, Niklas Schnelle wrote: > > > Hi Narendra, Hi All, > > > > > > According to Documentation/ABI/testing/sysfs-bus-pci you are responsible > > > for the index device attribute that is used by systemd to create network > > > interface names. > > > > > > Now we would like to reuse this attribute for firmware provided PCI > > > device index numbers on the s390 architecture which doesn't have > > > SMBIOS/DMI nor ACPI. All code changes are within our architecture > > > specific code but I'd like to get some Acks for this reuse. I've sent an > > > RFC version of this patch on 15th of March with the subject: > > > > > > s390/pci: expose a PCI device's UID as its index > > > > > > but got no response. Would it be okay to re-use this attribute for > > > essentially the same purpose but with index numbers provided by > > > a different platform mechanism? I think this would be cleaner than > > > further proliferation of /sys/bus/pci/devices//xyz_index > > > attributes and allows re-use of the existing userspace infrastructure. > > > > I'm missing an explanation that this change is safe for systemd and > > they don't have some hard-coded assumption about the meaning of existing > > index on s390. > > > > Thanks > > > Sure, good point. So first off yes this change does create new index > based names also on existing systemd versions, this is known and > intended and we'll certainly closely collaborate with any distributions > wishing to backport this change. > > As for being otherwise safe or having unintended consequences, Viktor > (see R-b) and I recently got the following PR merged in that exact area > of systemd to fix how hotplug slot derived interface names are > generated: > https://github.com/systemd/systemd/pull/19017 > In working on that we did also analyse the use of the index attribute > for hidden assumptions and tested with this attribute added. Arguably, > as the nature of that PR shows we haven't had a perfect track record of > keeping this monitored but will in the future as PCI based NICs become > increasingly important for our platform. We also have special NIC > naming logic in the same area for our channel based platform specific > NICs which was also contributed by Viktor. Thanks, this PR is exciting to read, very warm words were said about kernel developers :). Can you please summarize that will be the breakage in old systemd if this index will be overloaded? Thanks > > Thanks, > Niklas >