Passive translators (was: [PATCH] procfs: Ignore arguments for compatibility with Linux' procfs.)

[Thomas Schwinge]

Hi!

On Tue, 09 Jul 2013 15:00:00 +0200, Justus Winter 
<4winter@informatik.uni-hamburg.de> wrote:
> Quoting Pino Toscano (2013-07-09 10:52:56)
> > Alle martedì 9 luglio 2013, Justus Winter ha scritto:
> > > Ignore the --nodev, --noexec and --nosuid arguments.
> > 
> > Why nodev? The only consumer of it seems to be sysvinit, which has been 
> > patched to not pass nodev also on Hurd (in addition to kFreeBSD) when 
> > mounting /proc.
> 
> Not as far as I can see. mountkernfs.sh contains:
> 
>         domount "$MNTMODE" proc "" /proc proc "-onodev,noexec,nosuid"
> 
> Argument #6 is CALLER_OPTS and that is not modified, so this is also
> used on kFreeBSD.

I have a general question here.  We used to have such "mounts" being done
by means of passive translator settings, on /proc, for example.  It now
appears that you're re-working this to use the "active mount command" of
standard Unix (so, setting an active translator on /proc at each system
boot)?  Is the passive translator setting meant to go away then?

The same question came up in my mind already when I saw your /etc/fstab
patches go by; currently we use /etc/fstab only for fsck purposes.

I'm not convinced one approach is better than the other.  The passive
translator setting was a novel feature of the Hurd, given that it has no
direct equivalent (letting the registry in /etc/fstab aside) in Unix, and
Debian by default is such a Unix system, so Debian GNU/Hurd -- so far --
was different from that.  On the other hand, a passive translator setting
also is not quite what you'd get in a persistent system (which, I guess,
may partly have influenced this Hurd design decision?),
<http://en.wikipedia.org/wiki/Persistence_%28computer_science%29>.  As we
know, passive translators do have their issues, too, for example as
described in »3.5 Passive Translators and Naming« in
<http://www.gnu.org/software/hurd/hurd/critique.html>, or
<http://www.gnu.org/software/hurd/open_issues/translators_set_up_by_untrusted_users.html>
also has some discussion about passive translators.

Is this enough to generally declare passive translators "obsolete"?


Aside from the presumed elegancy aspect of the first approach, whether
the "system default configuration" in /servers/ is done by means of
passive translator settings on the respective nodes, or by active
translators that are started at system boot based on information present
in /etc/ configuration files, seems basically just like a detail question
(at least when leaving the idea aside that passive translators are only
activated on demand, and thus consume no resources by default).


Is Debian GNU/Hurd going to replace all usage of passive translators with
active ones, set at system boot, or a mixture of passive and active (by
design), or a mixture of passive and active for the time being (because
some things currently can't sensibly be implemented by using active
translators only, such as the mishmash in /dev/ -- which eventually was
meant to be replaced by a "super devfs translator", which likely will
have issues on its own)?


Grüße,
 Thomas

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