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 377344AD4B5; Fri, 11 Sep 2026 18:25:03 +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=1789151105; cv=none; b=QNsH910ngB6MJvwRqohIlvdDg2YPmQBDe9uQJNY0nU7WFuVzbmTVXAKRnnTagidONzwPL2tgww4+/vF4uuw4X+wDPMVG3y9JN/aHoFYIqKf///yd71gB5LvSo4f8hc8j2HU1sgSE3cAbdeDH/P4E2iTq2iaHkvPUdS/MORiTBI8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789151105; c=relaxed/simple; bh=8i6j2kj0J2WWxOx2+kQFd3c8jjZ5eNeBsSQ7ZDg5KOs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TLGTKBa88oKwQ4Mc6iHZUlMTsgIoBFbmZS5SgP5Qwf1CdY8qX7pHPfeneSy7W0V8POYt2YEhiFKCowcnDrOT7aB1r6vEiCqkhxGPgHLytFkDx7IJmcWK/CjNcT+NwwhQuaP2u+zKQOviN0SYLjWW7GZLJC9prdVzTrF0g4zfZcE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RlyhOewu; 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="RlyhOewu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A91F51F000FF; Fri, 11 Sep 2026 18:24:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789151103; bh=KKNF1BR24z2hq8JFatue1wvWlNPndjqBIvnaGAC0Uqw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=RlyhOewuf7WxDS24cLgcR2lbriVrR+lDPmqXJfTUdN7HYmOtPDB7j29KJoKmkpr7u 9dqd9F2fStdlb21DzGnuUfNIyWROL1gANAZJ0qjYWB/6XSgAE66XdKzhjEvztMH6y/ WNkeO+nCbxN55cNXSDyzriyPcgD6rjPOPIYw0L/X8Mo9q2WLBD6vR9suM9BrdAOCwm cE91VtBDpXsIt+yE63okTLAec+OzU8mjS9nuLiDwWrUoQHXbcg+8fewCBFye1Z/s/i Cf5IKRquZU9fbuPpaiB3MB88n5PvmtmvjQc+S508IpZltqFEuRdIU52lhVvEaAEoVf 0f7uPMOW2n9yg== Date: Fri, 11 Sep 2026 19:24:50 +0100 From: "Lorenzo Stoakes (ARM)" To: Nicolas Schier Cc: David Laight , Nathan Chancellor , Linus Torvalds , 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 , =?utf-8?B?QmrDtnJu?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , Onur =?utf-8?B?w5Z6a2Fu?= , Jonathan Corbet , Randy Dunlap , 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 Subject: Re: [PATCH 12/23] kbuild: avoid re-running compiler and linker probes Message-ID: References: <20260908-build-speedup-v1-0-5dc1ac01672d@kernel.org> <20260908-build-speedup-v1-12-5dc1ac01672d@kernel.org> <178901395292.3971858.13236774094648272066.b4-review@b4> <20260910-translucent-sweet-sidewinder-7acacb@l-nschier-aarch64> <20260911183333.1df0f2e2@pumpkin> <20260911-invaluable-indigo-seal-e31aec@l-nschier-aarch64> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260911-invaluable-indigo-seal-e31aec@l-nschier-aarch64> On Fri, Sep 11, 2026 at 08:17:57PM +0200, Nicolas Schier wrote: > On Fri, Sep 11, 2026 at 06:33:33PM +0100, David Laight wrote: > > On Thu, 10 Sep 2026 17:42:35 +0200 > > Nicolas Schier wrote: > > > > ... > > > Yes, skimming through the patch, I thought about that, too. Moving more > > > cc option checks to Kconfig will make building out-of-tree kmods with a > > > different compiler more dangerous. Maybe we will have to make the > > > warning in Makefile's prepare (external kmods) target a bit louder. > > > > One problem is that distributions have a nasty habit of shipping kernels > > that are compiled with a different compiler version to they actually > > ship as a compiler. > > In some cases the versions are clearly the same - but the version > > strings differ. > > yeah, I guess you hit the mark. I mean this is a problem that already exists for any flags already specified in Kconfig. Out-of-tree modules are historically something that we don't go to great lengths to support and haven't historically worried about breaking, either. I'm sure distros can find ways around this if a problem were to arise. But I don't think it's something to worry about all that much. I expect a _lot_ of these, in any case, would only require the compilers to be within a fair few major versions of one another anyway. > > -- > Nicolas -- Cheers, Lorenzo