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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F3453C31E52 for ; Sat, 15 Jun 2019 06:18:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D16272184E for ; Sat, 15 Jun 2019 06:18:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726047AbfFOGSn (ORCPT ); Sat, 15 Jun 2019 02:18:43 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:18581 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725828AbfFOGSn (ORCPT ); Sat, 15 Jun 2019 02:18:43 -0400 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 67AD2C45D52F06B7FBEE; Sat, 15 Jun 2019 14:18:40 +0800 (CST) Received: from [127.0.0.1] (10.133.213.239) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.439.0; Sat, 15 Jun 2019 14:18:36 +0800 Subject: Re: [PATCH] PCI: hv: Fix build error without CONFIG_SYSFS To: Michael Kelley , "bhelgaas@google.com" , Stephen Hemminger , "sashal@kernel.org" , Dexuan Cui , "linux-hyperv@vger.kernel.org" References: <20190531150923.12376-1-yuehaibing@huawei.com> CC: "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" From: Yuehaibing Message-ID: <7d8ca05e-7519-45d8-e694-d31e221696d5@huawei.com> Date: Sat, 15 Jun 2019 14:18:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.133.213.239] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 2019/6/2 6:59, Michael Kelley wrote: > From: YueHaibing Sent: Friday, May 31, 2019 8:09 AM >> >> while building without CONFIG_SYSFS, fails as below: >> >> drivers/pci/controller/pci-hyperv.o: In function 'hv_pci_assign_slots': >> pci-hyperv.c:(.text+0x40a): undefined reference to 'pci_create_slot' >> drivers/pci/controller/pci-hyperv.o: In function 'pci_devices_present_work': >> pci-hyperv.c:(.text+0xc02): undefined reference to 'pci_destroy_slot' >> drivers/pci/controller/pci-hyperv.o: In function 'hv_pci_remove': >> pci-hyperv.c:(.text+0xe50): undefined reference to 'pci_destroy_slot' >> drivers/pci/controller/pci-hyperv.o: In function 'hv_eject_device_work': >> pci-hyperv.c:(.text+0x11f9): undefined reference to 'pci_destroy_slot' >> >> Select SYSFS while PCI_HYPERV is set to fix this. >> > > I'm wondering if is the right way to fix the problem. Conceptually > is it possible to setup & operate virtual PCI devices like > pci-hyperv.c does, even if sysfs is not present? Or is it right to > always required sysfs? > > The function pci_dev_assign_slot() in slot.c has a null implementation > in include/linux/pci.h when CONFIG_SYSFS is not defined, which > seems to be trying to solve the same problem for that function. And > if CONFIG_HOTPLUG_PCI is defined but CONFIG_SYSFS is not, > pci_hp_create_module_link() and pci_hp_remove_module_link() > look like they would have the same problem. Maybe there should > be degenerate implementations of pci_create_slot() and > pci_destroy_slot() for cases when CONFIG_SYSFS is not defined? > > But I'll admit I don't know the full story behind how PCI slots > are represented and used, so maybe I'm off base. I just noticed > the inconsistency in how other functions in slot.c are handled. > > Thoughts? 268a03a42d33 ("PCI: drivers/pci/slot.c should depend on CONFIG_SYSFS") make slot.o depends CONFIG_SYSFS commit 268a03a42d3377d5fb41e6e7cbdec4e0b65cab2e Author: Alex Chiang Date: Wed Jun 17 19:03:57 2009 -0600 PCI: drivers/pci/slot.c should depend on CONFIG_SYSFS There is no way to interact with a physical PCI slot without sysfs, so encode the dependency and prevent this build error: drivers/pci/slot.c: In function 'pci_hp_create_module_link': drivers/pci/slot.c:327: error: 'module_kset' undeclared This patch _should_ make pci-sysfs.o depend on CONFIG_SYSFS too, but we cannot (yet) because the PCI core merrily assumes the existence of sysfs: drivers/built-in.o: In function `pci_bus_add_device': drivers/pci/bus.c:89: undefined reference to `pci_create_sysfs_dev_files' drivers/built-in.o: In function `pci_stop_dev': drivers/pci/remove.c:24: undefined reference to `pci_remove_sysfs_dev_files' So do the minimal bit for now and figure out how to untangle it later. If No CONFIG_SYSFS, slot.o is not build > > Michael > >