Re: [uml-devel] [Pkg-uml-pkgs] How is user-mode-linux using /dev/shm/?

[Blaisorblade <blaisorblade@yahoo.it>]

On Friday 29 September 2006 19:46, Mattia Dongili wrote:
> On Thu, Sep 28, 2006 at 05:51:43PM -0400, Jeff Dike wrote:
> > On Thu, Sep 28, 2006 at 09:47:27PM +0200, Mattia Dongili wrote:
> > > On Thu, Sep 28, 2006 at 08:14:32PM +0200, Petter Reinholdtsen wrote:
> > > > 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.
> >
> > UML needs a non-noexec place to keep a file that will be used as its
> > physical memory.  A tmpfs mount is greatly preferred for performance
> > reasons as well as tmpfs being the only filesystem supporting
> > MADV_REMOVE, which is used for memory hotplug.
>
> Thinking of a Debian only fix for the above, does simply playing with
> default_tmpdir in arch/um/os-Linux/mem.c (probably in which_tmpdir())
> suffice to use /lib/init/rw/.ramfs as default?
Is it world-writable with the sticky bit set as /tmp and /dev/shm? I do not 
know 

-- 
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! 
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