Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933183AbcKYSBC (ORCPT ); Fri, 25 Nov 2016 13:01:02 -0500 Received: from mail-io0-f194.google.com ([209.85.223.194]:35212 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755547AbcKYSAx (ORCPT ); Fri, 25 Nov 2016 13:00:53 -0500 MIME-Version: 1.0 In-Reply-To: <20161125114018.12421474@roar.ozlabs.ibm.com> References: <20161123205338.GA12050@angband.pl> <20161123210256.31501-1-kilobyte@angband.pl> <20161124044028.GA12704@gmail.com> <20161124162051.5e336127@roar.ozlabs.ibm.com> <20161124060050.GA788@gmail.com> <20161124182026.34e6570b@roar.ozlabs.ibm.com> <20161124073639.GA12728@kroah.com> <20161124185322.1e2a492c@roar.ozlabs.ibm.com> <20161124095622.GA14390@kroah.com> <20161124213152.30d8d27a@roar.ozlabs.ibm.com> <20161124152410.GC30905@kroah.com> <20161125114018.12421474@roar.ozlabs.ibm.com> From: Linus Torvalds Date: Fri, 25 Nov 2016 10:00:46 -0800 X-Google-Sender-Auth: 2XkxmS5Lx1eOzH6FtzPKX02gWZQ Message-ID: Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm To: Nicholas Piggin Cc: Greg Kroah-Hartman , Ingo Molnar , Al Viro , Adam Borowski , Michal Marek , Philip Muller , Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrew Morton , Peter Zijlstra , linux-arch , linux-kbuild Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1499 Lines: 34 On Thu, Nov 24, 2016 at 4:40 PM, Nicholas Piggin wrote: >> >> Yes, manual "marking" is never going to be a viable solution. > > I guess it really depends on how exactly you want to use it. For distros > that do stable ABI but rarely may have to break something for security > reasons, it should work and give exact control. No. Because nobody else will care, so unless it's like a single symbol or something, it will just be a maintenance nightmare. > What else do people *actually* use it for? Preventing mismatched modules > when .git version is not attached and release version of the kernel has > not been bumped. Is that it? It used to be very useful for avoiding loading stale modules and then wasting days on debugging something that wasn't the case when you had forgotten to do "make modules_install". Change some subtle internal ABI issue (add/remove a parameter, whatever) and it would really help. These days, for me, LOCALVERSION_AUTO and module signing are what I personally tend to use. The modversions stuff may just be too painful to bother with. Very few people probably use it, and the ones that do likely don't have any overriding reason why. So I'd personally be ok with just saying "let's disable it for now", and see if anybody even notices and cares, and then has a good enough explanation of why. It's entirely possible that most users are "I enabled it ten years ago, I didn't even realize it was still in my defconfig". Linus