From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 8EF9A3793CA for ; Fri, 10 Jul 2026 18:12:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783707138; cv=none; b=gGcoD1HuGbUzGl8Rk/P7MrUlLdGMPUFbimdTzOIztVCpMks65uQbOnXOccF8HlfxIszDcjLBK4FPHxubvGeFDJlAPjiZjEu6elZWmj/zw00jhPXL3fmte8eohwtSX+mz+Bz2QZbucWY/4yyY19HWTaolveb99emmwhYRBdF08zI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783707138; c=relaxed/simple; bh=BKL6Rk2KLRqhhfEKLA52CqShWwmoo8HPoXEPDsfMXnA=; h=From:To:Cc:Subject:In-Reply-To:Date:Message-ID:MIME-Version: Content-Type; b=qAfRXUNweg1UATWSo+p3Gy2k+QLvmv9E3PqREIig5addeR8YfKT96JUTk5F3p2uCc/Uwszzjs27TL/i6+VN9PiImPDPcfDgP/ubYs0uPci4HY4ynXp+cbvHYb/idm/IctYnjkWkzkcJSfgNEBG9T8p6/wqh8X11U1BhvkUHCN48= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KEA77Vsn; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KEA77Vsn" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1783707136; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to; bh=1JDiQFjqXL3cUBFhV0EcF2HIut9LhbtaAo+gzV0P68U=; b=KEA77Vsn3cHcvZiFr7eMCokhHf1RtHW8anVKFNk8Vp4jtG05boMRQYVZd+6Q+NWJRe3PgD cunIquaTO9igQjl9dS8iPjXMOy8JqB5LrkjnT3/9UbUGRzyjljdJ5Q8D6xCp24G/n40Ps2 0VTfCUsmKowjNoyvczXPUJIbBXzJkRQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-75-nOUyW220ONCc7SFclxLdWA-1; Fri, 10 Jul 2026 14:12:13 -0400 X-MC-Unique: nOUyW220ONCc7SFclxLdWA-1 X-Mimecast-MFC-AGG-ID: nOUyW220ONCc7SFclxLdWA_1783707132 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (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 mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 29F5C180266F; Fri, 10 Jul 2026 18:12:12 +0000 (UTC) Received: from greed.delorie.com (unknown [10.22.89.250]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D65273692C; Fri, 10 Jul 2026 18:12:11 +0000 (UTC) Received: from greed.delorie.com.redhat.com (localhost [127.0.0.1]) by greed.delorie.com (8.16.1/8.16.1) with ESMTP id 66AICAa2771738; Fri, 10 Jul 2026 14:12:10 -0400 From: DJ Delorie To: Alejandro Colomar Cc: linux-man@vger.kernel.org Subject: Re: man/man8/ldconfig.8: document system-wide tunables In-Reply-To: (message from Alejandro Colomar on Fri, 10 Jul 2026 16:31:18 +0200) Date: Fri, 10 Jul 2026 14:12:10 -0400 Message-ID: Precedence: bulk X-Mailing-List: linux-man@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Alejandro Colomar writes: > mandoc: .tmp/man/man8/ldconfig.8:212:85: STYLE: input text line longer than 80 bytes: Allow the tunable to... Fixed. > mandoc: .tmp/man/man8/ldconfig.8:250:2: WARNING: skipping paragraph macro: PP empty > mandoc: .tmp/man/man8/ldconfig.8:270:2: WARNING: skipping paragraph macro: PP empty Fixed. I think. We need a better language for this ;-) > lint-man-poems: .tmp/man/man8/ldconfig.8: Use semantic newlines (see man-pages(7)): > 222: The tunable only applies to AT_SECURE (i.e. setuid, or elevated Maybe fixed? Better at least. The linter still complains despite me splitting it up: .B @ The tunable only applies to AT_SECURE (i.e. setuid, or elevated capabilities) processes. > an.tmac:.tmp/man/man8/ldconfig.8:92: style: .IR expects at least 2 arguments, got 1 > an.tmac:.tmp/man/man8/ldconfig.8:195: style: .IR expects at least 2 arguments, got 1 > an.tmac:.tmp/man/man8/ldconfig.8:197: style: .IR expects at least 2 arguments, got 1 Fixed. >> +.SH INCLUDES > > I think this section belongs in new manual pages, ld.so.conf(5) and > tuinables.conf(5), which would describe the formats of those files. >> +.SH TUNABLES > > Same here; I think this belongs in tunables.conf(5). I looked for ld.so.conf.5 but didn't see one (which kinda surprised me, but a lot of ldconfig isn't documented either in the man pages or in the glibc manual) so went with "what was there". I have a slight preference for "get this change in quickly" as glibc is releasing with the new funcionality soon(ish) but if you want me to split these two out, I can do that too. Or do it later. >> +The files >> +.IR /etc/ld.so.conf > > s/IR/I/ Really, really, want a better language for this... ;-) diff --git a/man/man8/ldconfig.8 b/man/man8/ldconfig.8 index ee024b8f6..19f1ddf43 100644 --- a/man/man8/ldconfig.8 +++ b/man/man8/ldconfig.8 @@ -17,6 +17,8 @@ .SH SYNOPSIS .IR conf ] .RB [ \-r\~\c .IR root ] +.RB [ \-t\~\c +.IR tunconf ] .IR directory \~.\|.\|. .YS .SY /sbin/ldconfig @@ -85,6 +87,11 @@ .SH DESCRIPTION .P Failure to follow this pattern may result in compatibility issues after an upgrade. +.P +If the file +.I /etc/tunables.conf +exists, it contains one tunable per line. These tunables are stored +in the cache and applied to every process at its startup. .SH OPTIONS .TP .BI \-\-format= fmt @@ -157,6 +164,12 @@ .SH OPTIONS .I root as the root directory. .TP +.BI \-t\~ tunconf +Use +.I tunconf +instead of +.IR /etc/tunables.conf . +.TP .B \-\-verbose .TQ .B \-v @@ -177,9 +190,85 @@ .SH OPTIONS .B \-N is also specified, the cache is still rebuilt. +.SH INCLUDES +The files +.I /etc/ld.so.conf +and +.I /etc/tunables.conf +allow lines to start with the word +.I include +followed by a path wildcard, +and will include any files matching that wildcard. +.SH TUNABLES +Each line in the file +.I /etc/tunables.conf +specifies a tunable, +which is a name and value separated by an equals sign. +Each line may include zero or more words or symbols at the beginning: +.TP +.B overridable +.TQ +.B + +Allow the tunable to be overridden by the environment variable +(this is the default). +.TP +.B nonoverridable +.TQ +.B \- +Do not allow the tunable to be overridden by the environment variable. +.TP +.B onlysecure +.TQ +.B @ +The tunable only applies to AT_SECURE +(i.e. setuid, or elevated capabilities) +processes. +.TP +.B nonsecure +.TQ +.B $ +The tunable only applies to non-AT_SECURE processes (this is the default). +.TP +.B anysecure +.TQ +.B * +The tunable only applies to both AT_SECURE and non-AT_SECURE processes. +.P +The file may also contain +.I filters , +which limit the tunables following it, up to the end of the file +(or end of the included file, or start of a new included file) +or a line with only +.B [] +on it. The syntax is: +.RS +.P +[ +.I filter +: +.I pattern +] +.RE +.TP +.B proc +The +.I proc +filter limits the following tunables to processes starting from the +file matching the pattern. +The file may be fully qualified or just the basename. +.P +Example config file: +.P +.RS +.nf +glibc.malloc.arenas_max=5 +onlysecure glibc.malloc.arenas_max=1 +-glibc.pthread.rseq=1 +[proc:/bin/bad.program] +-glibc.pthread.rseq=0 +.fi +.RE .SH FILES -.\" FIXME Since glibc-2.3.4, "include" directives are supported in ld.so.conf -.\" .\" FIXME Since glibc-2.4, "hwcap" directives are supported in ld.so.conf .PD 0 .TP @@ -191,6 +280,11 @@ .SH FILES one per line, in which to search for libraries. .TP +.I /etc/tunables.conf +contains a list of tunables, +one per line, +to apply to all newly created processes. +.TP .I /etc/ld.so.cache contains an ordered list of libraries found in the directories specified in