From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1GT1rv-0002ci-8g for user-mode-linux-devel@lists.sourceforge.net; Thu, 28 Sep 2006 12:48:27 -0700 Received: from aa012msr.fastwebnet.it ([85.18.95.72]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1GT1rt-00038p-JQ for user-mode-linux-devel@lists.sourceforge.net; Thu, 28 Sep 2006 12:48:27 -0700 Date: Thu, 28 Sep 2006 21:47:27 +0200 From: Mattia Dongili Message-ID: <20060928194727.GC8519@inferi.kami.home> References: <2flhcyrq2nr.fsf@saruman.uio.no> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <2flhcyrq2nr.fsf@saruman.uio.no> Subject: Re: [uml-devel] [Pkg-uml-pkgs] How is user-mode-linux using /dev/shm/? List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: Petter Reinholdtsen Cc: User Mode Linux Maintainers , pkg-sysvinit-devel@lists.alioth.debian.org, Paolo Giarrusso , UML-devel Thanks Petter for writing, I was going to followup to the sysvinit bug :) I'm Cc-ing upstream too. On Thu, Sep 28, 2006 at 08:14:32PM +0200, Petter Reinholdtsen wrote: > > Hi > > I am one of the sysvinit maintainers. Recently we changed the mount > options of /dev/shm/, and got a bug report about uml refusing to start > (#386945). Because of this, I am curious how uml uses /dev/shm/. Is > it using the shm-functions in glibc, or something else? Please > explain how it work. I don't think it uses shm* functions, as far as I can tell the /dev/shm location is sensible to $TMP, $TEMP or $TEMPDIR, thus changing one of them to a different location goes farther than what's reported in the bureport: $ TMPDIR=./TMP linux ubd0=rootfs_debian-sid.172.20.0.20 ubd1=swap-172.20.0.20 eth0=tuntap,,,172.20.0.19 umid=debian mem=128 Checking that ptrace can change system call numbers...OK Checking syscall emulation patch for ptrace...OK Checking advanced syscall emulation patch for ptrace...OK Checking for tmpfs mount on /dev/shm...OK Checking PROT_EXEC mmap in ./TMP/...OK Checking for the skas3 patch in the host: - /proc/mm...not found - PTRACE_FAULTINFO...not found - PTRACE_LDT...not found UML running in SKAS0 mode Mapping memory: Cannot allocate memory Don't know now, it's maybe easy to fix, there's a nice global variable set to "/dev/shm" in arch/um/os-Linux/mem.c and UML uses mkstemp() to create files. > To make some writable tmpfs available to those in need of such system, > and to avoid using /dev/shm/ which is reserved for the shm-functions, > I just uploaded sysvinit version 2.86.ds1-26. It will mount a tmpfs > on /lib/init/rw/ that can be used instead. If /lib/init/rw/.ramfs > exist, that mount point is a tmpfs. I'm not sure if this last change > will make it into Etch or not, but I hope so, to solve any problems > with packages previously using /dev/shm/ as a generic tmpfs file > system. Well, I'd actually prefer if you could remove the noexec flag from /dev/shm. I understand the security reasons given in the bugreport but I'd prefer avoid having to deal with one more Debian-only (is it?) thing given the soon to come general freeze. Thanks -- mattia :wq! ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel