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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A1F84C433F5 for ; Wed, 4 May 2022 21:09:25 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KtqFw0wyzz3bqt for ; Thu, 5 May 2022 07:09:24 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=OV+zeMEq; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4641:c500::1; helo=dfw.source.kernel.org; envelope-from=helgaas@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=OV+zeMEq; dkim-atps=neutral Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KtqF93sYgz2ynk for ; Thu, 5 May 2022 07:08:45 +1000 (AEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DE761616A3; Wed, 4 May 2022 21:08:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F213FC385A4; Wed, 4 May 2022 21:08:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651698522; bh=y1eZ0VyTuh3OSu3SZE5hnm+6Lqgi7WUL9wuM4x9LDoU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=OV+zeMEqAJx67x4OYYs/T+PwaB9EPFjKfNsjZzrWwMVM3NvLvNFpPf0wDtRgV6hPg C/vW0RHXE+D3VHZkPbIlT7vV9H8IzZjwKHGMG7joXJdlZZ7WJg8oDJqQBcpyc4rw/O yxAB78m6HEpQDrzbacEayJr8iiRcV1EWi7mSGZxb5IDhBXSg0dvOB0Jpz0xpdKT8q1 53W71wtG3ZAAJTFq4C2Bw331IYIMqmF+azzr+0ky2kC+20quz/B/hGbW52VPMkvf2m sc7xISbNbAO/Ktfv/RlrnLm3f7ClaHPrrdpfMsEfr0tf1mKOlzAyEBnIbIHem9sEJj ZVekgou/eHQhA== Date: Wed, 4 May 2022 16:08:40 -0500 From: Bjorn Helgaas To: Niklas Schnelle Subject: Re: [RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary Message-ID: <20220504210840.GA469916@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220429135108.2781579-2-schnelle@linux.ibm.com> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rich Felker , "open list:IA64 \(Itanium\) PLATFORM" , "open list:SUPERH" , Catalin Marinas , Dave Hansen , "open list:MIPS" , "James E.J. Bottomley" , "open list:SPARC + UltraSPARC \(sparc/sparc64\)" , "open list:RISC-V ARCHITECTURE" , Will Deacon , linux-arch@vger.kernel.org, Yoshinori Sato , Helge Deller , "maintainer:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , Russell King , Ingo Molnar , Geert Uytterhoeven , linux-pci@vger.kernel.org, Matt Turner , Albert Ou , Arnd Bergmann , "open list:M68K ARCHITECTURE" , Ivan Kokshaysky , Paul Walmsley , Thomas Gleixner , "moderated list:ARM PORT" , Richard Henderson , Arnd Bergmann , Michal Simek , Thomas Bogendoerfer , "open list:PARISC ARCHITECTURE" , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Palmer Dabbelt , "open list:ALPHA PORT" , Borislav Petkov , "open list:LINUX FOR POWERPC \(32-BIT AND 64-BIT\)" , "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Fri, Apr 29, 2022 at 03:49:59PM +0200, Niklas Schnelle wrote: > We introduce a new HAS_IOPORT Kconfig option to indicate support for > I/O Port access. In a future patch HAS_IOPORT=n will disable compilation > of the I/O accessor functions inb()/outb() and friends on architectures > which can not meaningfully support legacy I/O spaces such as s390 or > where such support is optional. So you plan to drop inb()/outb() on architectures where I/O port space is optional? So even platforms that have I/O port space may not be able to use it? This feels like a lot of work where the main benefit is to keep Kconfig from offering drivers that aren't of interest on s390. Granted, there may be issues where inb()/outb() does the wrong thing such as dereferencing null pointers when I/O port space isn't implemented. I think that's a defect in inb()/outb() and could be fixed there. Bjorn