From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/10378 Path: news.gmane.org!.POSTED!not-for-mail From: Alexander Monakov Newsgroups: gmane.linux.lib.musl.general Subject: Re: Re: sysconf(_SC_ARG_MAX) broken in musl. Date: Sun, 14 Aug 2016 23:20:21 +0300 (MSK) Message-ID: References: <20160810203602.GA15995@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Trace: blaine.gmane.org 1471206051 25844 195.159.176.226 (14 Aug 2016 20:20:51 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 14 Aug 2016 20:20:51 +0000 (UTC) User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) Cc: Rob Landley , musl@lists.openwall.com To: Rich Felker Original-X-From: musl-return-10391-gllmg-musl=m.gmane.org@lists.openwall.com Sun Aug 14 22:20:47 2016 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1bZ1tn-0006Vl-88 for gllmg-musl@m.gmane.org; Sun, 14 Aug 2016 22:20:47 +0200 Original-Received: (qmail 5984 invoked by uid 550); 14 Aug 2016 20:20:45 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 5966 invoked from network); 14 Aug 2016 20:20:44 -0000 In-Reply-To: <20160810203602.GA15995@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:10378 Archived-At: On Wed, 10 Aug 2016, Rich Felker wrote: > Has anyone else looked into the issue enough to have a good opinion on > it, or at least additional information that would add to discussion? To provide a data point, I've been told that userspace QEmu used to limit the cumulative args length in a more restrictive way than the kernel (1/4th stack limit). The observed failure mode was this: xargs running under qemu-user would build the command line according to what glibc thought would be accepted by the syscall (based on large stack size), but then the syscall would fail because qemu-user wouldn't process that many args. I understand this is not much, since qemu-user is unreliable in other ways, and this particular issue has been fixed in QEmu regardless, but still I think it contributes to the general point. Is the concern that 128KB is too low to be usable? My understanding is that _SC_ARG_MAX is not broken in musl (contrary to what the subject says), just conservative (in a healthy way in this case imho). Alexander