Re: SCO: "thread creation is about a thousand times faster than on

From: Marco Colombo (
Date: Thu Aug 31 2000 - 14:10:29 EST

On Tue, 29 Aug 2000, Pavel Machek wrote:

> Hi!
> > > So you need some hackery to make mount(8) cause change in all
> > > namespaces at once. Whatever is done, this will be gross.
> > > I suppose you'd require a loopback of some sort, so that one
> > > might rip the real filesystem out from under /var/mail instead
> > > of trying to unmount it in 50 different namespaces... ugh.
> >
> > Not. Loopback would be gross, but I'm not proposing it. OTOH, getting all
> > mailreaders work with IMAP with _no_ changes in said mailreaders is a
> > Good Thing(tm). So is free (for mailreaders) support of any weird
> > protocol, format and location of mailbox, locking scheme, etc. - do it in
> > one place and that's it. Everything looks like we have the mailbox in
> > fixed format on local filesystem, no matter WTF is actually out there.
> > And guess what? It doesn't have to be one process and it's nowhere near
> > the kernel mode, or even suid.
> What does this have to do with private namespaces?
> mailfsd /dev/coda0 --enable-imap &
> mount /dev/coda0 /var/spool/mail

So every user will see /var/spool/mail. There must be a single mailfsd
for all users.

With private namespaces, every user can run his/her own mailfsd,
privately mount /var/spool/mail, and run a mailer program to access
one or more IMAP mailbox as /var/spool/mail/<mailbox>.

But I must say I don't really get the difference in running my own
mailfsd, mounting ~/mail and having the mailer program read IMAP
mailboxes there (OK, /var/spool/mail/<user> is the default INBOX
for many mailers, and some of them don't let you change that... but
this is a minor issue, just recompile them).

All I need is a private mount point (and privileges to mount on it).

> It looks easy to me, today and without private namespaces.
> [Shall I hack podfuk into providing imap? Okay, it would not be easy
> because
> * /var/spool/mail/xxx is _writable_, so your imap dream is probably
> dream. What does your mailfs do when someone does cat /bin/bash >
> * podfuk is has file granularity
> I could see it working with some kind of directory format, however.]
> Pavel
> --
> I'm "In my country we have almost anarchy and I don't care."
> Panos Katsaloulis describing me w.r.t. patents at
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      ____/  ____/   /
     /      /       /			Marco Colombo
    ___/  ___  /   /		      Technical Manager
   /          /   /			 ESI s.r.l.
 _____/ _____/  _/

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