From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CFA3D3A05C2; Mon, 14 Sep 2026 18:43:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789411433; cv=none; b=ArCddPGEHsNdQtVUKAJjVdZGSjPV5sSPBVd/jjUGOfPy/B13k2dF8Cg+q1ul7sCJVrE/yoGyN4rilYez1SIm1aw71LPMM0jf2jd78CXStLaz0mf6qLFZeh08WjGjBY2tHSTgcUraHs9cdLecH+y3ffezAEhO3FYtGhrTLXuLPNE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789411433; c=relaxed/simple; bh=zy03KGEW1YeeekDBJmyUfQNa60AVoG7T/gD0XbgBOzw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Vqms+xFfN9PNsRmarWEbRJ3p2dW6/MzeorQGL8y3XsRrgpG3ebTjNxcp6ymd5wj2mdzPEWIppKM6MNSri0tnkC8W4KE1U9W48EYf8lh3uoOAk5JEbM1JkdAoxLpson+H8am7CD+m5/tvDErumyoVwnjKhMo9JMsxQfBzUAc6dmU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G0/xHYvA; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="G0/xHYvA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEDAA1F00893; Mon, 14 Sep 2026 18:43:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789411430; bh=bo6GJLiDf9mVwm6AXXi7iuVJHoavl3dsdCOXGh6V4XE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=G0/xHYvAtQ4HOxtFGJbJlA22cMjDZl+N56G9hsoC0tQv8qT6/15zEdvADlDxeYuQh ae8Q6N4X+AKq3TVZGTbZs+4oj+vIEXo4zgpz9hevYG1TM/+/i/QF6MM11pZBxxyVq0 vraPPnQ7ZUCWXbPqXPeQbWc8N1vmP5oiVA5uoJav1ICknNtIaaUdkQaW70pDvAs5vE 974HTKmZo3bFjISiUMqs3buCdhMg059Qh11CETtTBafCHxBYrVccHqoUfj37NZD6rk zB9+I7SuAegOhvn9/uOVYU9JJ+Kw272HbWhBcTsqzySDRKTHj2bpbmSHp8inaUBp/U YZD68D5G/qndA== Date: Mon, 14 Sep 2026 11:43:50 -0700 From: Kees Cook To: "Lorenzo Stoakes (ARM)" Cc: Linus Torvalds , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Masahiro Yamada , Alexey Gladkov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , Ilias Apalodimas , Josh Poimboeuf , Peter Zijlstra , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , Onur =?iso-8859-1?Q?=D6zkan?= , Jonathan Corbet , Randy Dunlap , "Gustavo A. R. Silva" , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, Jens Axboe , linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 00/21] kbuild: significantly speed up kernel builds Message-ID: <202609141139.AEF875252@keescook> References: <20260914-build-speedup-v2-0-39817ec5db23@kernel.org> <202609140833.88C0E16E50@keescook> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Sep 14, 2026 at 07:25:28PM +0100, Lorenzo Stoakes (ARM) wrote: > On Mon, Sep 14, 2026 at 08:41:39AM -0700, Kees Cook wrote: > > Did you try Clang CONFIG_LTO=y builds? > > I tried a CONFIG_LTO_CLANG_THIN in order to check that the *.mod.S stuff > worked correctly, all working correctly. Okay, thanks! I did the same just now too. It seems to be just fine. > I can try to get some profiling numbers for thin and full if you want? Mostly I wanted to know if it worked still, and I guess for profiling, I'd want to make sure it didn't regress how long it took to build. :) > Well I rewrote the majority of them, so this is a stinging critique of my > commit message writing I guess :) Oops! Sorry. I'll go through them again, but I felt like the objtool commit logs were very long, but perhaps it is justified. ;) > (N.B. I have had feedback like that on a fair few human-written commit > messages of mine lately so there might be some validity to that ;) And as I said, I get told I'm often too terse, so perhaps my sensing here is broken. :P > > One area I think might solved via an LLM is the 3-pass kallsyms stuff. > > If we could get a deterministic kallsyms build in 1 pass, that would be > > very nice. A lot of people have tried, but it has eluded upstreaming. > > "going from three passes to one would save around 8s on an allmodconfig > build and 2 to 3s on defconfig, out of tails that are currently roughly 25s > and 8s." says the LLM :) so that actually does seem worthwhile. It's what I'm always staring at when I do incrementals. ;) > But I think best as a follow up? Yeah, I would imagine it'd be separate. (I think a few of these sets of changes could be landed separately too, like the pigz work.) -- Kees Cook 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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E9370C88E6F for ; Mon, 14 Sep 2026 18:44:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Hhg10/pA9XWVsAoy3wK2fVb4NEqRA1J2Z/MwBnBiulA=; b=SFPZL09B0h/Ziy +cnXcpuwIlu/Z0dgzQjCaorpJpakamXkAzQ5zh+1DzwAmcRnA399/UekKD6vGn50pqRv13UqRzxgb qvEsZkQh+6qpG09JtlvbO20osg0a2+7Y10/ddcQpM4OamZu+FKs70yVykJd6ZUp5GeOdRgJGONdhA xRtyYcJJir//XmUaEmfzlt1zFXinVjXbEGu6FhOlPVJXhnA1jFlQdd5k1OzOJBYjHlnOx6zOwD1fW C1DNXhQzngRbpAC8WXHoyAqq1FfNm+w2bbcbmEM+HKeOduCMZgFyDSccnI48FMv4tAEx3teACnxJm c0aZda0tB9gD+BN94XMw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x6Bej-00000004TGN-2SRp; Mon, 14 Sep 2026 18:43:53 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x6Beh-00000004TFz-3oix; Mon, 14 Sep 2026 18:43:52 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 1C69860252; Mon, 14 Sep 2026 18:43:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCFB61F000FF; Mon, 14 Sep 2026 18:43:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789411430; bh=bo6GJLiDf9mVwm6AXXi7iuVJHoavl3dsdCOXGh6V4XE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=G0/xHYvAtQ4HOxtFGJbJlA22cMjDZl+N56G9hsoC0tQv8qT6/15zEdvADlDxeYuQh ae8Q6N4X+AKq3TVZGTbZs+4oj+vIEXo4zgpz9hevYG1TM/+/i/QF6MM11pZBxxyVq0 vraPPnQ7ZUCWXbPqXPeQbWc8N1vmP5oiVA5uoJav1ICknNtIaaUdkQaW70pDvAs5vE 974HTKmZo3bFjISiUMqs3buCdhMg059Qh11CETtTBafCHxBYrVccHqoUfj37NZD6rk zB9+I7SuAegOhvn9/uOVYU9JJ+Kw272HbWhBcTsqzySDRKTHj2bpbmSHp8inaUBp/U YZD68D5G/qndA== Date: Mon, 14 Sep 2026 11:43:50 -0700 From: Kees Cook To: "Lorenzo Stoakes (ARM)" Cc: Linus Torvalds , Nathan Chancellor , Nicolas Schier , Nick Desaulniers , Bill Wendling , Justin Stitt , Masahiro Yamada , Alexey Gladkov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Arnd Bergmann , Catalin Marinas , Will Deacon , Mark Rutland , Ard Biesheuvel , Ilias Apalodimas , Josh Poimboeuf , Peter Zijlstra , Miguel Ojeda , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , Onur =?iso-8859-1?Q?=D6zkan?= , Jonathan Corbet , Randy Dunlap , "Gustavo A. R. Silva" , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-riscv@lists.infradead.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-doc@vger.kernel.org, Jens Axboe , linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 00/21] kbuild: significantly speed up kernel builds Message-ID: <202609141139.AEF875252@keescook> References: <20260914-build-speedup-v2-0-39817ec5db23@kernel.org> <202609140833.88C0E16E50@keescook> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Sep 14, 2026 at 07:25:28PM +0100, Lorenzo Stoakes (ARM) wrote: > On Mon, Sep 14, 2026 at 08:41:39AM -0700, Kees Cook wrote: > > Did you try Clang CONFIG_LTO=y builds? > > I tried a CONFIG_LTO_CLANG_THIN in order to check that the *.mod.S stuff > worked correctly, all working correctly. Okay, thanks! I did the same just now too. It seems to be just fine. > I can try to get some profiling numbers for thin and full if you want? Mostly I wanted to know if it worked still, and I guess for profiling, I'd want to make sure it didn't regress how long it took to build. :) > Well I rewrote the majority of them, so this is a stinging critique of my > commit message writing I guess :) Oops! Sorry. I'll go through them again, but I felt like the objtool commit logs were very long, but perhaps it is justified. ;) > (N.B. I have had feedback like that on a fair few human-written commit > messages of mine lately so there might be some validity to that ;) And as I said, I get told I'm often too terse, so perhaps my sensing here is broken. :P > > One area I think might solved via an LLM is the 3-pass kallsyms stuff. > > If we could get a deterministic kallsyms build in 1 pass, that would be > > very nice. A lot of people have tried, but it has eluded upstreaming. > > "going from three passes to one would save around 8s on an allmodconfig > build and 2 to 3s on defconfig, out of tails that are currently roughly 25s > and 8s." says the LLM :) so that actually does seem worthwhile. It's what I'm always staring at when I do incrementals. ;) > But I think best as a follow up? Yeah, I would imagine it'd be separate. (I think a few of these sets of changes could be landed separately too, like the pigz work.) -- Kees Cook _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv