From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-relay-canonical-1.canonical.com (smtp-relay-canonical-1.canonical.com [185.125.188.121]) by sourceware.org (Postfix) with ESMTPS id 65A483835804 for ; Mon, 12 Jul 2021 10:04:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 65A483835804 Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPS id BE3F840334 for ; Mon, 12 Jul 2021 10:04:24 +0000 (UTC) Received: by mail-pf1-f199.google.com with SMTP id x35-20020a056a0018a3b029032d069176ceso277273pfh.20 for ; Mon, 12 Jul 2021 03:04:24 -0700 (PDT) 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=VKIyYtDn8TceEx4kTHvvnnBiwOdtDczEEvVQd0awbO0=; b=R1GevZv1m6us+INubwro0OxJkt0mn5OgxLWMaqRlgEpYf/IC+S92tdZSNIeHZvLYJ7 GG2AY4PIZskayyAsMBaucwPkH1VNMlkJTS/RiZgpO8G0k+KwEt+ej9rXoSdRv8+GsmPq s2x8HytlILdVXma57Q3D8BY4U8psIrvizxK2viUolZsk1f5+0XqRNTR8AQ3o79XcBl0w xsVv+5LUohJ5ml4XiFeA9LOHUhD9/OSRxmE6WDQXTUQrC8rmUd5HtOptL1ndhrno+Ebz +lU/E7r2ApqNQn5SeryPX8hXeNE/n8aw5jfeEK8nQzYSFf4XOcOe1os9qBUU1rDWDVm4 KsGA== X-Gm-Message-State: AOAM532ny7hJtr3VKXO0Wc9wlwW6urTeTgh4qgIptydqts0g0yGBxXFz u7y61Tm3BvLl9DN/P/sYMqW9nR474hVVQNZ3Kjkou08Fmjdv5TVZgRGctMUJwx9SxIui3ABLR4r hCBVdweFQ1rxxUfB4AElMn+kGp4QjUCLDnCW9j9iB1IlJcU4X7W4TTA== X-Received: by 2002:a17:90a:28a5:: with SMTP id f34mr17574025pjd.107.1626084262820; Mon, 12 Jul 2021 03:04:22 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxYaWuwnJFtIj4dLJyBcvY1yt7++0bwox4sUwZohUxMtK/rG+3p78eL/7QnpSavqyxZMiBaW1sfxgfifR5epx8= X-Received: by 2002:a17:90a:28a5:: with SMTP id f34mr17574003pjd.107.1626084262521; Mon, 12 Jul 2021 03:04:22 -0700 (PDT) MIME-Version: 1.0 References: <87o8e0p92r.fsf@oldenburg.str.redhat.com> In-Reply-To: <87o8e0p92r.fsf@oldenburg.str.redhat.com> From: Michael Hudson-Doyle Date: Mon, 12 Jul 2021 22:04:11 +1200 Message-ID: Subject: Re: Undefined use of weak symbols in gnulib To: Florian Weimer Cc: bug-gnulib@gnu.org, libc-alpha@sourceware.org, binutils@sourceware.org X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, HTML_MESSAGE, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Jul 2021 10:04:29 -0000 On Tue, 27 Apr 2021 at 17:53, Florian Weimer wrote: > lib/glthread/lock.h has this: > > | /* The way to test at runtime whether libpthread is present is to test > | whether a function pointer's value, such as &pthread_mutex_init, is > | non-NULL. However, some versions of GCC have a bug through which, in > | PIC mode, &foo != NULL always evaluates to true if there is a direct > | call to foo(...) in the same function. To avoid this, we test the > | address of a function in libpthread that we don't use. */ > [snip] This will become an urgent issue with glibc 2.34, which defines > pthread_mutexattr_gettype unconditionally. Certain gnulib modules will > stop working until the binaries are relinked. I expect the issue is > already visible with earlier glibc versions if libpthread is > unexpectedly present at run time. > Did this thread ever reach a conclusion? I'm testing a snapshot of glibc 2.34 in ubuntu and running into this issue -- bison segfaults on startup on ppc64el. There is some talk of 'rebuilding the world' once 2.34 lands in a distro but that might be hard because I suspect the world might be too broken to do that (maybe it's not that bad really... but it doesn't sound like fun). Cheers, mwh