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=-5.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 65E07C433E0 for ; Fri, 5 Feb 2021 17:51:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D23B64D79 for ; Fri, 5 Feb 2021 17:51:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233571AbhBEQI0 (ORCPT ); Fri, 5 Feb 2021 11:08:26 -0500 Received: from mail.cybernetics.com ([173.71.130.66]:40446 "EHLO mail.cybernetics.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233499AbhBEQCH (ORCPT ); Fri, 5 Feb 2021 11:02:07 -0500 X-Greylist: delayed 725 seconds by postgrey-1.27 at vger.kernel.org; Fri, 05 Feb 2021 11:02:07 EST X-ASG-Debug-ID: 1612546268-0fb3b014601af740001-xx1T2L Received: from cybernetics.com ([10.10.4.126]) by mail.cybernetics.com with ESMTP id LjUxXFWAiKKmTNJg; Fri, 05 Feb 2021 12:31:08 -0500 (EST) X-Barracuda-Envelope-From: tonyb@cybernetics.com X-ASG-Whitelist: Client Received: from [10.157.2.224] (account tonyb HELO [192.168.200.1]) by cybernetics.com (CommuniGate Pro SMTP 5.1.14) with ESMTPSA id 10522515; Fri, 05 Feb 2021 12:31:05 -0500 Subject: Re: Kernel version numbers after 4.9.255 and 4.4.255 To: Jiri Slaby , Greg Kroah-Hartman X-ASG-Orig-Subj: Re: Kernel version numbers after 4.9.255 and 4.4.255 References: From: Tony Battersby Cc: linux-kernel@vger.kernel.org, Jari Ruusu , David Laight , Christoph Biedl Message-ID: <0b12bac9-1b4e-ec4a-8a45-5eb3f1dbbeca@cybernetics.com> Date: Fri, 5 Feb 2021 12:31:05 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-Barracuda-Connect: UNKNOWN[10.10.4.126] X-Barracuda-Start-Time: 1612546268 X-Barracuda-URL: https://10.10.4.122:443/cgi-mod/mark.cgi X-Barracuda-BRTS-Status: 1 X-Virus-Scanned: by bsmtpd at cybernetics.com X-Barracuda-Scan-Msg-Size: 1445 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/4/21 6:00 AM, Jiri Slaby wrote: > Agreed. But currently, sublevel won't "wrap", it will "overflow" to > patchlevel. And that might be a problem. So we might need to update the > header generation using e.g. "sublevel & 0xff" (wrap around) or > "sublevel > 255 : 255 : sublevel" (be monotonic and get stuck at 255). > > In both LINUX_VERSION_CODE generation and KERNEL_VERSION proper. My preference would be to be monotonic and get stuck at 255 to avoid breaking out-of-tree modules.  If needed, add another macro that increases the number of bits that can be used to check for sublevels > 255, while keeping the old macros for compatibility reasons.  Since sublevels > 255 have never existed before, any such checks must be newly-added, so they can be required to use the new macros. I do not run the 4.4/4.9 kernels usually, but I do sometimes test a wide range of kernels from 3.18 (gasp!) up to the latest when bisecting, benchmarking, or debugging problems.  And I use a number of out-of-tree modules that rely on the KERNEL_VERSION to make everything work.  Some out-of-tree modules like an updated igb network driver might be needed to make it possible to test the old kernel on particular hardware. In the worst case, I can patch LINUX_VERSION_CODE and KERNEL_VERSION locally to make out-of-tree modules work.  Or else just not test kernels with sublevel > 255. Tony Battersby Cybernetics