From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f42.google.com (mail-qv1-f42.google.com [209.85.219.42]) (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 A82D611191 for ; Fri, 19 May 2023 15:57:36 +0000 (UTC) Received: by mail-qv1-f42.google.com with SMTP id 6a1803df08f44-62387baa403so4833386d6.1 for ; Fri, 19 May 2023 08:57:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1684511855; x=1687103855; 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=ZlIVAJkfUZuaa/mIdEmkmyvFCFGMfQ33OBwJnbKZILY=; b=lGGNkc8nfCv/+xd2tZWAVIdZN9LnuxzOUwfAxn6XE17QzOycTPTNHliz2ZFhtUh+YF JfMZXk0Yo/TMVeGFSlU3/F7eUMtnFJBCXPCt26x0DGb+Aw7txIF2aO5F9oHYF/FDUcxh GExjFkSKHEtoweTKlQE9o4+WW11YS3OY+aZ7a09D+dQPabHwOa1Epx/EnbWh1XUYda7+ wI2uhfXAkB4w3HxyEfqCNZpJflCbxhnWPV8BVHOI9XqeBIuKc62zGR/nGqmcLpxtjnMu G1upkcZHOuuu1ofZSEnNwVWpvUkbkyTS+oBc8BsvaswqSUBCY2+6kDIgIaX8H9VOpJ92 viYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684511855; x=1687103855; 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=ZlIVAJkfUZuaa/mIdEmkmyvFCFGMfQ33OBwJnbKZILY=; b=AsMU74n1EiGNBS6sps5xhSLEHZSLI89c6g5y+4CQaWGjGpzdlWvpw7kDGrK5Q/pzM+ zpgBPdTxvoMvbaUfXuUuRXTTJR/0kXWzVEHvNTAQMIYS0zOJ4Be1PvMO7p1Kefqq/Voc yeK0HpkcZxRb0Igd20ZHg8zI6ZREYPkRYvCVwGdWBsTxlHSGHUv/tTVXzXsC3v7txZ7F aNDL2pE5Ut2PQ9LHyHOO/2y4SYvStiza8PQAxoY9HLlkyP4r3Dtm9/0L4q3rm1VmRSsB rNgGkaegh4EQtKCsIYh7ZIsjzAdBweY5rE2w3ni+GJojdrHQPusfUhYFv428dh9/uiWM Ko1Q== X-Gm-Message-State: AC+VfDyjgsuEfk5B5GbbVPP9L706tfUmYVQWV2MFfTwXU8K7IR57ESFD xPB6sQ79/6IuzDjh/pEwkFf5REO8sQgFJs+cRHoG4w== X-Google-Smtp-Source: ACHHUZ7am3g5K1M8XXYl0TVpF1TkbnbjfGOU5itzTMNk/WigjyM4lXkOk9kRkA/Mj26X0uyicFXOI+bHipdr7bUnf/U= X-Received: by 2002:a05:6214:401d:b0:616:859a:471a with SMTP id kd29-20020a056214401d00b00616859a471amr5347827qvb.17.1684511855305; Fri, 19 May 2023 08:57:35 -0700 (PDT) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20220919170828.3718437-1-ndesaulniers@google.com> <597ef55f-e7c1-ab60-b4aa-0071ff4b5e0e@collabora.com> <89961dfc-d40f-78e4-5d34-b86b7d152182@collabora.com> <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> In-Reply-To: <875y8ok9b5.fsf@rcn-XPS-13-9305.i-did-not-set--mail-host-address--so-tickle-me> From: Nick Desaulniers Date: Fri, 19 May 2023 08:57:24 -0700 Message-ID: Subject: Re: [PATCH v4] Makefile.compiler: replace cc-ifversion with compiler-specific macros To: =?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, Greg KH Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, May 19, 2023 at 1:35=E2=80=AFAM Ricardo Ca=C3=B1uelo wrote: > > On jue, may 18 2023 at 14:12:30, Nick Desaulniers wrote: > > That's a higher risk change (and has my name on the tested-by tag, yike= s). > > > > So is that the culprit of the boot failure you're observing? > > Right now it is. > > Here's a test run using that commit > (5750121ae7382ebac8d47ce6d68012d6cd1d7926): > https://lava.collabora.dev/scheduler/job/10373216 > > Here's one with the commit right after that one > (26ef40de5cbb24728a34a319e8d42cdec99f186c): > https://lava.collabora.dev/scheduler/job/10371513 > > Then one with 26ef40de5cbb24728a34a319e8d42cdec99f186c with a revert > commit for 5750121ae7382ebac8d47ce6d68012d6cd1d7926 on top: > https://lava.collabora.dev/scheduler/job/10371882 > > But I'm not confident enough to jump ahead and call this a kernel > regression, specially after the bisector confidently said that about > your commit and then it turned out none of us could reproduce it. 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. > > There have been some cases where a commit made a test fail (kernel > failing to load, for instance) and the real problem was that the kernel > got bigger than the target was capable of handling. So not a problem > with the commit at all, it was just that the memory mappings needed to > be redefined for that target. What I'm saying is that sometimes a > regression report is really uncovering a problem in the test setup > rather than introducing a bug. Maybe this is one of those cases. > > Cheers, > Ricardo --=20 Thanks, ~Nick Desaulniers