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 B99CC165F1A for ; Sat, 8 Aug 2026 03:08:19 +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=1786158501; cv=none; b=AWSAo+a54u4iVhhovmbJ+bKU2Ag3Zu7/TvpR+zS2poaMlyhUQc9BwUmPtb48b9pcUHT3k6rb63ug1chtWvpKro2BSqiVG5d6hVyqBVvCZZY/MM6JSwUNpu4gHulWcEgIoNLj+0TzDRaU5PLZ6z7Ogn0Td8wYpEzNw+uWhCBPFTo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786158501; c=relaxed/simple; bh=VkdtMufc6VCALnR66NB/Tb8di6IwbSQpot4HQkbtOmg=; h=From:To:Cc:Subject:In-Reply-To:Date:Message-ID:MIME-Version: Content-Type; b=UGshJpaJ1vwcJhjNVWLmwklofVzO/WDbq6t7QFtEs208dDLTBknGOZldiAxNlHys7voODqdthM5cZP/aTKESJKgsdLnc7s6TkHpI+mQDbzSjBpTpMa5FyadoUpw+vnrOnW0KL25rIH/ZiYCIFbRO316jdX/S1LmqhximVUwiZZo= 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=hGkOMUVu; 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="hGkOMUVu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1786158498; 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=EewByttH/YlYYyp0tcRWG+vkzacgySwmEnH5HRLcmXg=; b=hGkOMUVuO0iUZRKoYcwhsPml+1puOuswFStzwMJ5zGteB+04P8+kWLTl8s022Wk+EZSPi8 sqrk8ja7yonQbPqIE379YHOAv4HT1XLw1vkIvvGYmdorSMaLB02SrNgFKtSONmYYFxla9M u1IbDREZg0Xg+Cz96sYw+RbdpxeC9aU= 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-593-mgV8vA9pP3i3OpwSmOuqcw-1; Fri, 07 Aug 2026 23:08:12 -0400 X-MC-Unique: mgV8vA9pP3i3OpwSmOuqcw-1 X-Mimecast-MFC-AGG-ID: mgV8vA9pP3i3OpwSmOuqcw_1786158492 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 DE2AA1800471; Sat, 8 Aug 2026 03:08:11 +0000 (UTC) Received: from greed.delorie.com (unknown [10.22.89.120]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9B3DB19560AB; Sat, 8 Aug 2026 03:08:11 +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 67838A0k3466609; Fri, 7 Aug 2026 23:08:10 -0400 From: DJ Delorie To: Alejandro Colomar Cc: linux-man@vger.kernel.org Subject: Re: [PATCH v5 2/4] man/man5/tunables.conf: Document system-wide tunables config In-Reply-To: (message from Alejandro Colomar on Sat, 8 Aug 2026 00:36:43 +0200) Date: Fri, 07 Aug 2026 23:08:10 -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 3.0 on 10.30.177.17 I'm ok with : The resulting data is read when the program starts execution. This is what I've got so far: commit 8ed803ba1e814dd7efdeec787b9b278c2e44be83 Author: DJ Delorie Date: Fri Aug 7 23:07:04 2026 -0400 man/man5/tunables.conf: Document system-wide tunables config Signed-off-by: DJ Delorie diff --git a/man/man5/tunables.conf.5 b/man/man5/tunables.conf.5 new file mode 100644 index 000000000..a27f78cde --- /dev/null +++ b/man/man5/tunables.conf.5 @@ -0,0 +1,144 @@ +.TH tunables.conf 5 (date) "Linux man-pages (unreleased)" +.SH NAME +tunables.conf \- tunables configuration file +.SH SYNOPSIS +.nf +.B /etc/tunables.conf +.fi +.SH DESCRIPTION +Tunables are a feature in the GNU C Library +that allows application authors and distribution maintainers +to alter the runtime library behavior to match their workload. +For a list of supported tunables, +please consult the glibc manual +that corresponds to your installed version of glibc, +or run the following command: +.P +.in +4n +.EX +ld.so \-\-list\-tunables +.EE +.P +The file is parsed by +.BR \%ldconfig (8) +and the results stored in +.IR /etc/ld.so.cache . +The resulting data is read when the program starts execution. +.P +Each line in the file +.I /etc/tunables.conf +specifies a tunable, +which is specified with a string of the form +.IB name = value \f[R].\f[] +.P +The syntax allows lines to start with the keyword +.B include +followed by a +.BR \%glob (7) +pattern. +Files matching that pattern will be processed +as if their contents were included at that point. +.P +Each line may include zero or more keywords or symbols at the beginning, +which affect how each tunable affects each processes. +The keywords must be separated by whitespace, +but the symbols need not be. +.TP +.B overridable +.TQ +.B + +Allow the tunable to be overridden by the +.B GLIBC_TUNABLES +environment variable when the process runs +(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 applies only to +.B AT_SECURE +processes, +such as one started from a set-user-ID program, +or one with elevated capabilities. +.TP +.B nonsecure +.TQ +.B $ +The tunable applies only to +.RB non- AT_SECURE +processes (this is the default). +.TP +.B anysecure +.TQ +.B * +The tunable applies to both +.B AT_SECURE +and +.RB non- AT_SECURE +processes. +.P +The file may also contain +.IR filters , +which limit the tunables following it. +The effects of a filter are terminated by +any of the following: +.IP \[bu] 3 +The end of the file. +.PD 0 +.IP \[bu] +The end of an included file. +.IP \[bu] +An +.B include +directive. +.IP \[bu] +A new (possibly empty) filter. +.PD +.P +The syntax is: +.P +.in +4n +.EX +.BI [ filter : pattern ] +.EE +.in +.TP +.B proc +The +.B proc +filter limits the following tunables to processes +whose name matches the pattern. +The pattern may be an absolute path +or just the base name. +.P +A filter can also be empty: +.BR [] . +Such a filter has no effects. +.SH FILES +.TP +.I /etc/tunables.conf +.TP +.I /etc/ld.so.cache +cached copy of tunables +.SH EXAMPLES +Example configuration file: +.P +.in +4n +.EX +glibc.malloc.arenas_max=5 +onlysecure glibc.malloc.arenas_max=1 +\-glibc.pthread.rseq=1 +[proc:/bin/bad.program] +\-glibc.pthread.rseq=0 +[proc:some.program] +\-glibc.malloc.mmap_threshold=65536 +.EE +.in +.SH SEE ALSO +.BR ld.so (8), +.BR ldconfig (8)