From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f52.google.com (mail-qv1-f52.google.com [209.85.219.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 94AF1171B8 for ; Mon, 22 May 2023 19:52:25 +0000 (UTC) Received: by mail-qv1-f52.google.com with SMTP id 6a1803df08f44-6239a0f1609so20476166d6.0 for ; Mon, 22 May 2023 12:52:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1684785144; x=1687377144; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=p52m+WWp6aApwkHVTkNg5kh/c1TUE8xWnOr/swu4YQM=; b=lRpK3qNuuiQELF1mYf+pdqtoRndN/uBy+fRujNOBmFoKNNZHXdQGn1YvzpvVdJmEsc o3aMGlzGMRo5bQ1kgH0uISw+aX/9dQxYn75ifiSczdRoxgRETgSHrFpUk4Qz4Bw1R2IJ MhyAJcR09p9R18n7Ziq0C2mjuHP7B4FjFS+arj7kNxBLuT0bp/xmQbQiuodgr3hztHl/ 4CPSJAhCovLJTkhnzO8WN/7IrW0xiT3nz9471apMj6tER1aIMTmaI6NmSsejQ1mOhrk3 3MLyEXrK/w5i0DCPURMZjSV0NUoL5yt0rFbJz/MTHoB08PJ8bVAkFVwax4tQar1VwO4p hNrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684785144; x=1687377144; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=p52m+WWp6aApwkHVTkNg5kh/c1TUE8xWnOr/swu4YQM=; b=gevnANIIBRDs52FiBD1f3e/grce2Ek3pEXtc3FT0hqiBsS2PyvmT7p1+8nvmMUZX32 Ekev1jkefNabt/LM7SBYTLceavgaMP6ybcOSXvDUEazyVKxkRVzK/lFHcsSR7z/9WjkR 7ZZ5LBhvNit6fMDtp9W8CI0Rvq+CqK1qLEi9RTHQXiTLZ/smN/atYrC1TmoV0kX5GW6l lXN+jE0SqMrbRECQ6+EDxLWIbLcvEoA6ePvRh+lW96+mWMhbu5Kevp43RgoqECeJySY6 pIQ6tGCAatlxiQX3wcpUo2In7dSU6RxOL34nBstxm0VwO/OMTUSL4+MYWe8UJ/PsD1y6 DQmw== X-Gm-Message-State: AC+VfDyNuj4X47uOMQhLgDgF/EwJdhGBPis8WmzWdGq9KhVs4MB/IHBa xIUmGSpwc86vrVAGK7FQ2HVZ8FZAcQYKIObigEHV9g== X-Google-Smtp-Source: ACHHUZ62p53t5Jx/dLsMCHu7hh9zeJ6bLdglFzoT+d04I0no2SNO9KMZS5dewAaI/LY85SD7r51/PuKHsSa9AFk227A= X-Received: by 2002:a05:6214:f0a:b0:5fd:7701:88c5 with SMTP id gw10-20020a0562140f0a00b005fd770188c5mr23825727qvb.6.1684785144362; Mon, 22 May 2023 12:52:24 -0700 (PDT) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <17c91d37-7d9c-0df4-2438-2b30ca0b5777@collabora.com> <878rdlk9bi.fsf@rcn-XPS-13-9305.i-did-not-set--mail-host-address--so-tickle-me> <875y8ok9b5.fsf@rcn-XPS-13-9305.i-did-not-set--mail-host-address--so-tickle-me> <87353ok78h.fsf@rcn-XPS-13-9305.i-did-not-set--mail-host-address--so-tickle-me> <2023052247-bobtail-factsheet-d104@gregkh> In-Reply-To: <2023052247-bobtail-factsheet-d104@gregkh> From: Nick Desaulniers Date: Mon, 22 May 2023 12:52:13 -0700 Message-ID: Subject: Re: [PATCH v4] Makefile.compiler: replace cc-ifversion with compiler-specific macros To: Greg KH , Maksim Panchenko , =?UTF-8?Q?Ricardo_Ca=C3=B1uelo?= Cc: Shreeya Patel , Michal Marek , Masahiro Yamada , Linux Kernel Mailing List , clang-built-linux , Bill Wendling , Nathan Chancellor , regressions@lists.linux.dev, "gustavo.padovan@collabora.com" , Guillaume Charles Tucker , denys.f@collabora.com, kernelci@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, May 22, 2023 at 9:52=E2=80=AFAM Greg KH wrote: > > On Mon, May 22, 2023 at 12:09:34PM +0200, Ricardo Ca=C3=B1uelo wrote: > > On vie, may 19 2023 at 08:57:24, Nick Desaulniers wrote: > > > It could be; if the link order was changed, it's possible that this > > > target may be hitting something along the lines of: > > > https://isocpp.org/wiki/faq/ctors#static-init-order i.e. the "static > > > initialization order fiasco" > > > > > > I'm struggling to think of how this appears in C codebases, but I > > > swear years ago I had a discussion with GKH (maybe?) about this. I > > > think I was playing with converting Kbuild to use Ninja rather than > > > Make; the resulting kernel image wouldn't boot because I had modified > > > the order the object files were linked in. If you were to randomly > > > shuffle the object files in the kernel, I recall some hazard that may > > > prevent boot. > > > > I thought that was specifically a C++ problem? But then again, the > > kernel docs explicitly say that the ordering of obj-y goals in kbuild i= s > > significant in some instances [1]: > > Yes, it matters, you can not change it. If you do, systems will break. > It is the only way we have of properly ordering our init calls within > the same "level". Ah, right it was the initcall ordering. Thanks for the reminder. (There's a joke in there similar to the use of regexes to solve a problem resulting in two new problems; initcalls have levels for ordering, but we still have (unexpressed) dependencies between calls of the same level; brittle!). +Maksim, since that might be relevant info for the BOLT+Kernel work. Ricardo, https://elinux.org/images/e/e8/2020_ELCE_initcalls_myjosserand.pdf mentions that there's a kernel command line param `initcall_debug`. Perhaps that can be used to see if 5750121ae7382ebac8d47ce6d68012d6cd1d7926 somehow changed initcall ordering, resulting in a config that cannot boot? --=20 Thanks, ~Nick Desaulniers