From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id EF2157D04D for ; Fri, 1 Mar 2019 17:22:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726416AbfCARWB (ORCPT ); Fri, 1 Mar 2019 12:22:01 -0500 Received: from mail-qt1-f194.google.com ([209.85.160.194]:34533 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387418AbfCARWB (ORCPT ); Fri, 1 Mar 2019 12:22:01 -0500 Received: by mail-qt1-f194.google.com with SMTP id w4so28677297qtc.1 for ; Fri, 01 Mar 2019 09:22:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=U/9thOjurA+lIRFK0bp+ZG70JtmlEraTbsN+PJD2O9I=; b=Le5Ueu53kunQMlXpyqwk2e4kYM6t5IvX9AiUfdGQPxrJ+VxZfmHQWHOJuSdMOPIR34 PQ6VZS1rE/d5mtizV/jGDXMz0UYRflhcUPSg5ynGCSn8TDqDFvpGOx85DqwQtavqgkFR +TzA2XnKhu3cb9avBoiHXkJ4xszJSyLbVco+s= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=U/9thOjurA+lIRFK0bp+ZG70JtmlEraTbsN+PJD2O9I=; b=hgEc8aUYCD5H6msaRppRj80xu+aJEI/84SLsOkTzFDNxr9BSegZSKyFwRk3A7Ybvu9 K0PkMdUMGNw8NzAdWwx7YZDvhB/UeQvY1KQ6WDABdWy+g8vEUdqDYC99A/OAvkDIZwPN gqtMtpjfDunR+Ky0zh8tPt2Ua3cCe/PE+05QMTOjrw2nJZyG4IeUMIzcYU7X1jkZYU5z gx6f333zEyWLyy5NwBCUPXtJRzaUGX4YgIl3eFWgvuoqBiX4QKX6ZHu5z7iLHdFB8CnV S4wHiYTVmSuF5xtfv2JWGX5VJC/ChdOeeSvRDzFELn6UWGyTJNEAgCe9MgqGllMORT2Z 7TPQ== X-Gm-Message-State: APjAAAX5ZrVca8bv6ThyTavC8nTVSdGMr/UQSwI3lprXrTFyQNzXZqUj YkWxptv/uahYHFawB2el91CBdg== X-Google-Smtp-Source: APXvYqx8qELjvvbvGFW2ax0aQPeF/drI8AnPQBY3nP2jPcGHy8fpGhR7rluWFXj7RpbHZCvxdQ0R2w== X-Received: by 2002:ac8:2bc1:: with SMTP id n1mr4777281qtn.176.1551460919817; Fri, 01 Mar 2019 09:21:59 -0800 (PST) Received: from localhost ([2620:0:1004:1100:cca9:fccc:8667:9bdc]) by smtp.gmail.com with ESMTPSA id j139sm12403640qke.26.2019.03.01.09.21.58 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 01 Mar 2019 09:21:58 -0800 (PST) Date: Fri, 1 Mar 2019 12:21:58 -0500 From: Joel Fernandes To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Andrew Morton , ast@kernel.org, atishp04@gmail.com, dancol@google.com, Dan Williams , gregkh@linuxfoundation.org, Guenter Roeck , Jonathan Corbet , karim.yaghmour@opersys.com, Kees Cook , kernel-team@android.com, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-devel@vger.kernel.org, Manoj Rao , Masahiro Yamada , paulmck@linux.vnet.ibm.com, "Peter Zijlstra (Intel)" , qais.yousef@arm.com, rdunlap@infradead.org, rostedt@goodmis.org, Shuah Khan , Thomas Gleixner , yhs@fb.com Subject: Re: [PATCH v3 1/2] Provide in-kernel headers for making it easy to extend the kernel Message-ID: <20190301172158.GB217990@google.com> References: <20190227193748.132301-1-joel@joelfernandes.org> <20190228173444.54403795211d80ba540b61cb@kernel.org> <20190228150054.GB156098@google.com> <20190301112826.ced40b59fb7e8118fa5b40d6@kernel.org> <20190301032611.GA78818@google.com> <20190301160309.2ddadeeb4aadbab4cdc88171@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190301160309.2ddadeeb4aadbab4cdc88171@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, Mar 01, 2019 at 04:03:09PM +0900, Masami Hiramatsu wrote: > Hi Joel, > > On Thu, 28 Feb 2019 22:26:11 -0500 > Joel Fernandes wrote: > > > On Fri, Mar 01, 2019 at 11:28:26AM +0900, Masami Hiramatsu wrote: [..] > > There are many usecases for this, I have often run into issues with Linux > > over the years not only with Android, but other distros, where I boot custom > > kernels with no linux-headers package. This is quite painful. It is > > convenient to have it as /proc file since the file is dependent on kernel > > being booted up and this will work across all Linux distros and systems. I > > feel that if you can keep an open mind about it, you will see that a lot of > > people will use this feature if it is accepted and there is a lot of positive > > feedback in earlier posts of this set. > > I don't complain about having headers for custom boot kernel. I agree with you > that having kernel headers for debugging is always good. :) > So google recommends built-in, it is reasonable. Ok, thanks :) > > > > > > The code to read the headers is based on /proc/config.gz code and uses > > > > > > the same technique to embed the headers. > > > > > > > > > > > > To build a module, the below steps have been tested on an x86 machine: > > > > > > modprobe kheaders > > > > > > rm -rf $HOME/headers > > > > > > mkdir -p $HOME/headers > > > > > > tar -xvf /proc/kheaders.tar.xz -C $HOME/headers >/dev/null > > > > > > cd my-kernel-module > > > > > > make -C $HOME/headers M=$(pwd) modules > > > > > > rmmod kheaders > > > > > > > > > > It seems a bit complex, but no difference from compared with carrying > > > > > kheaders.tar.gz. I think we would better have a psudo filesystem > > > > > which can mount this compressed header file directly :) Then it becomes > > > > > simpler, like > > > > > > > > > > modprobe headerfs > > > > > mkdir $HOME/headers > > > > > mount -t headerfs $HOME/headers > > > > > > > > > > And this doesn't consume any disk-space. > > > > > > > > I felt using a compressed tar is really the easiest way because of all the > > > > tools are already available. > > > > > > As I asked above, if the pure tarball is useful, you can simply ask vendors > > > to put the header tarball on their vendor directory. I feel making it as > > > a module is not a right way. > > > > I don't see what is the drawback of making it a module, it makes it well > > integrated into kernel build and ecosystem. I also didn't see any > > justification you're providing about why it cannot be a module. If you go > > through this and earlier threads, a lot of people are Ok with having a module > > option. And I asked several top kernel maintainers at LPC and many people > > suggested having it as a module. > > I meant, if we have a tarball, we don't need any operation of loading/unloading > kmodules. But if we have this as built-in, yes, this would be much easier to > deploy it to device. > > Anyway, having that option (make it as a module) is not bad. IMHO, that may > be more complicated than just have a tarball file, but it is a user's choice. > > OK, now I understand it. Sounds good. :) Just sent out v4. thanks, - Joel