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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0710EC33CAC for ; Thu, 6 Feb 2020 17:20:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBFFD214AF for ; Thu, 6 Feb 2020 17:20:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727866AbgBFRUc (ORCPT ); Thu, 6 Feb 2020 12:20:32 -0500 Received: from mail-ot1-f68.google.com ([209.85.210.68]:44183 "EHLO mail-ot1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727607AbgBFRUb (ORCPT ); Thu, 6 Feb 2020 12:20:31 -0500 Received: by mail-ot1-f68.google.com with SMTP id h9so6203335otj.11 for ; Thu, 06 Feb 2020 09:20:30 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MPn+BUojxUhOvsXrFiv8dsam9EtwMGmqIOyvBWWRIVg=; b=my9T83Nh4DYegINCr+ppfvW59yjT/nHFV85HgfNXHa3thQ3lY+S93ZuELeJTzq+zKF GbBko/eGNdW7z6llOITQPZE6HQ3FlCfIT1LnZBenGAOQE+KoLQKr7COtwq9P7h6TQkaO hfmLu8y+s5YsMpLpih6W49bosB90wx0UldZy6/xIrfIq3eqV2NLDHvuTn14Fpf8nJFZn 9ugyHnnoYbvXN33dZB64e+l011CstmSuEweJC2yuaweK6CYpNFA4010Z0lWosmvcFvfK W2f2PHoFKypshsMKDvKFLw6TedhkAGJjbKjcq89BCL6OKrHC6SUgEFSZ6VHnUO1WyEKg Vm5g== X-Gm-Message-State: APjAAAUr5H/NAb/aPE65jRAhsjE0PKzBDDD3uaLxmnnEf/gXTKZsYyHv eSGMWxIcxs+z+kqcC03is8700xM0xWbEiEMYBjC9Qxmo X-Google-Smtp-Source: APXvYqx+zyAEG5rElRpu+Yng0gLxdpYCjKKDUgx9uVlKE3hw10bdHLC72AOUE+idNkn/upnr3Y4BHBbMMqjQ8+LzpDI= X-Received: by 2002:a9d:dc1:: with SMTP id 59mr31297201ots.250.1581009630530; Thu, 06 Feb 2020 09:20:30 -0800 (PST) MIME-Version: 1.0 References: <20200114210316.450821675@goodmis.org> <20200114210336.259202220@goodmis.org> <20200206115405.GA22608@zn.tnic> <20200206234100.953b48ecef04f97c112d2e8b@kernel.org> In-Reply-To: <20200206234100.953b48ecef04f97c112d2e8b@kernel.org> From: Geert Uytterhoeven Date: Thu, 6 Feb 2020 18:20:15 +0100 Message-ID: Subject: Re: [for-next][PATCH 04/26] bootconfig: Add Extra Boot Config support To: Masami Hiramatsu Cc: Borislav Petkov , Steven Rostedt , Linux Kernel Mailing List , Ingo Molnar , Andrew Morton Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Hiramatsu-san, On Thu, Feb 6, 2020 at 3:42 PM Masami Hiramatsu wrote: > On Thu, 6 Feb 2020 12:54:05 +0100 > Borislav Petkov wrote: > > On Tue, Jan 14, 2020 at 04:03:20PM -0500, Steven Rostedt wrote: > > > diff --git a/init/Kconfig b/init/Kconfig > > > index a34064a031a5..63450d3bbf12 100644 > > > --- a/init/Kconfig > > > +++ b/init/Kconfig > > > @@ -1215,6 +1215,17 @@ source "usr/Kconfig" > > > > > > endif > > > > > > +config BOOT_CONFIG > > > + bool "Boot config support" > > > + select LIBXBC > > > + default y > > > > Any particular reason this is default y? Why should it be enabled by > > default on all boxes? > > Oh, you are not the first person asked that :) > > https://lkml.org/lkml/2019/12/9/563 > > And yes, I think this is important that will useful for most developers > and admins. Since the bootconfig already covers kernel and init options, > this can be a new standard way to pass args to kernel boot. > > And as I reported above thread, the memory footpoint of view, most code > and working memory are released after boot. Also, as Linus's suggested, > now this feature is enabled only if user gives "bootconfig" on the kernel > command line. So the side effect is minimized. With m68k/atari_defconfig, bloat-o-meter says: add/remove: 39/0 grow/shrink: 2/0 up/down: 13086/0 (13086) which is IMHO not that small for a "default y" option that may or may not be used. Especially: Function old new delta xbc_nodes - 8192 +8192 Any chance xbc_nodes can be allocated dynamically, and only when needed? Yes, there are industrial products running Linux on a current ARM SoC using the builtin 8 or 10 MiB of SRAM (+ XIP for the kernel), so these definitely want to say CONFIG_BOOT_CONFIG=n. Thanks! add/remove: 39/0 grow/shrink: 2/0 up/down: 13086/0 (13086) Function old new delta xbc_nodes - 8192 +8192 xbc_init - 854 +854 start_kernel 1020 1580 +560 copy_xbc_key_value_list - 362 +362 __xbc_parse_value - 324 +324 xbc_snprint_cmdline - 294 +294 xbc_node_compose_key_after - 266 +266 xbc_namebuf - 256 +256 xbc_add_sibling - 254 +254 xbc_node_find_next_leaf - 186 +186 xbc_node_find_child - 176 +176 __xbc_add_key - 162 +162 proc_boot_config_init - 124 +124 xbc_make_cmdline - 122 +122 xbc_node_find_value - 104 +104 xbc_node_find_next_key_value - 102 +102 __xbc_close_brace - 92 +92 find_match_node - 80 +80 __xbc_parse_keys - 78 +78 xbc_node_get_data - 64 +64 xbc_parse_key - 60 +60 skip_comment - 48 +48 xbc_destroy_all - 42 +42 xbc_node_get_parent - 38 +38 xbc_parse_error - 36 +36 xbc_node_get_child - 34 +34 xbc_node_get_next - 32 +32 boot_config_checksum - 30 +30 boot_config_proc_show - 26 +26 xbc_root_node - 20 +20 kzalloc.constprop 810 830 +20 xbc_node_index - 14 +14 xbc_node_num - 4 +4 xbc_data_size - 4 +4 xbc_data - 4 +4 saved_boot_config - 4 +4 last_parent - 4 +4 extra_init_args - 4 +4 extra_command_line - 4 +4 __initcall_proc_boot_config_init5 - 4 +4 xbc_debug_dump - 2 +2 Total: Before=3688860, After=3701946, chg +0.35% Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds