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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 52224C282DB for ; Mon, 21 Jan 2019 08:02:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28F4F20823 for ; Mon, 21 Jan 2019 08:02:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729262AbfAUICx convert rfc822-to-8bit (ORCPT ); Mon, 21 Jan 2019 03:02:53 -0500 Received: from terminus.zytor.com ([198.137.202.136]:34065 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728530AbfAUICw (ORCPT ); Mon, 21 Jan 2019 03:02:52 -0500 Received: from wld62.hos.anvin.org (c-24-5-245-234.hsd1.ca.comcast.net [24.5.245.234] (may be forged)) (authenticated bits=0) by mail.zytor.com (8.15.2/8.15.2) with ESMTPSA id x0KLwNvv2248914 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Sun, 20 Jan 2019 13:58:24 -0800 Date: Sun, 20 Jan 2019 13:58:15 -0800 User-Agent: K-9 Mail for Android In-Reply-To: <20190120161003.GB23827@google.com> References: <20190118225543.86996-1-joel@joelfernandes.org> <20190119102800.GB17723@infradead.org> <20190119103606.GA17400@kroah.com> <8BD4CB7A-944C-4EC5-A198-1D85C9EE28D6@zytor.com> <20190120161003.GB23827@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: [RFC] Provide in-kernel headers for making it easy to extend the kernel To: Joel Fernandes CC: Greg KH , Christoph Hellwig , linux-kernel@vger.kernel.org, Andrew Morton , ast@kernel.org, atishp04@gmail.com, Borislav Petkov , dancol@google.com, Ingo Molnar , Jan Kara , Jonathan Corbet , karim.yaghmour@opersys.com, Kees Cook , kernel-team@android.com, linux-doc@vger.kernel.org, Manoj Rao , Masahiro Yamada , paulmck@linux.vnet.ibm.com, "Peter Zijlstra (Intel)" , rdunlap@infradead.org, rostedt@goodmis.org, Thomas Gleixner , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , yhs@fb.com From: hpa@zytor.com Message-ID: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On January 20, 2019 8:10:03 AM PST, Joel Fernandes wrote: >On Sat, Jan 19, 2019 at 11:01:13PM -0800, hpa@zytor.com wrote: >> On January 19, 2019 2:36:06 AM PST, Greg KH > wrote: >> >On Sat, Jan 19, 2019 at 02:28:00AM -0800, Christoph Hellwig wrote: >> >> This seems like a pretty horrible idea and waste of kernel memory. >> > >> >It's only a waste if you want it to be a waste, i.e. if you load the >> >kernel module. >> > >> >This really isn't any different from how /proc/config.gz works. >> > >> >> Just add support to kbuild to store a compressed archive in >initramfs >> >> and unpack it in the right place. >> > >> >I think the issue is that some devices do not use initramfs, or >switch >> >away from it after init happens or something like that. Joel has >all >> >of >> >the looney details that he can provide. >> > >> >thanks, >> > >> >greg k-h >> >> Yeah, well... but it is kind of a losing game... the more in-kernel >stuff there is the less smiley are things to actually be supported. > >It is better than nothing, and if this makes things a bit easier and >solves >real-world issues people have been having, and is optional, then I >don't see >why not. > >> Modularizing is it in some ways even crazier in the sense that at >that point you are relying on the filesystem containing the module, >which has to be loaded into the kernel by a root user. One could even >wonder if a better way to do this would be to have "make >modules_install" park an archive file – or even a directory as opposed >to a symlink – with this stuff in /lib/modules. We could even provide a >tmpfs shim which autoloads such an archive via the firmware loader; >this might even be generically useful, who knows. > >All this seems to assume where the modules are located. In Android, we >don't >have /lib/modules. This patch generically fits into the grand scheme >things >and I think is just better made a part of the kernel since it is not >that >huge once compressed, as Dan also pointed. The more complex, and the >more >assumptions we make, the less likely people writing tools will get it >right >and be able to easily use it. > >> >> Note also that initramfs contents can be built into the kernel. >Extracting such content into a single-instance tmpfs would again be a >possibility > >Such an approach would bloat the kernel image size though, which may >not work >for everyone. The module based approach, on the other hand, gives an >option >to the user to enable the feature, but not have it loaded into memory >or used >until it is really needed. > >thanks, > > - Joel Well, where are the modules? They must exist in the filesystem. -- Sent from my Android device with K-9 Mail. Please excuse my brevity.