From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1GTe7E-0001fX-5V for user-mode-linux-devel@lists.sourceforge.net; Sat, 30 Sep 2006 05:38:48 -0700 Received: from smtp004.mail.ukl.yahoo.com ([217.12.11.35]) by mail.sourceforge.net with smtp (Exim 4.44) id 1GTe7D-0001Is-Hi for user-mode-linux-devel@lists.sourceforge.net; Sat, 30 Sep 2006 05:38:48 -0700 From: Blaisorblade Date: Sat, 30 Sep 2006 14:36:17 +0200 References: <2flhcyrq2nr.fsf@saruman.uio.no> <20060928194727.GC8519@inferi.kami.home> In-Reply-To: <20060928194727.GC8519@inferi.kami.home> MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200609301436.17978.blaisorblade@yahoo.it> 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: Mattia Dongili Cc: User Mode Linux Maintainers , pkg-sysvinit-devel@lists.alioth.debian.org, UML-devel , Petter Reinholdtsen On Thursday 28 September 2006 21:47, Mattia Dongili wrote: > Thanks Petter for writing, > I was going to followup to the sysvinit bug :) > > I'm Cc-ing upstream too. > 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 There is probably some additional bug here, it should be easy to fix. > 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?) It is not - it can happen on Gentoo too (actually, the issue there is simply that the manuals _recommend_ to use noexec for /dev/shm). > thing given the soon to come general freeze. As Jeff Dike explained, we just need to use an executable tmpfs mount. For a long time, we used /tmp and _suggested_ people to use tmpfs for it, or to use it elsewhere and point TMP there. And quite frankly, it would be nicer to make that a default (i.e. if /tmp is automatically a tmpfs mount, switching back there would be nice). In 2.4 days, using tmpfs for /tmp was bad for one issue: you could not do a loopback mount from tmpfs, and this broke mkinitrd; but that has been solved since then, for 2.6 at least. -- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade http://www.user-mode-linux.org/~blaisorblade Chiacchiera con i tuoi amici in tempo reale! http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com ------------------------------------------------------------------------- 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