Date: Sat, 15 Jul 2000 03:10:12 -0700 From: Julian Elischer <julian@elischer.org> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Coleman Kane <cokane@one.net>, hackers@FreeBSD.ORG Subject: Re: DEVFS Message-ID: <39703884.15FB7483@elischer.org> References: <4007.963643480@critter.freebsd.dk>
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Poul-Henning Kamp wrote:
>
> In message <20000715013940.A51575@cokane.yi.org>, Coleman Kane writes:
>
> >Who is currently working on the DEVFS? I emailed the last person
> >to commit to the HOWTO and got no response. I'd like to look into
> >finisheing this, and may start hacking if no one tells me otherwise...
Well, it was almost fully working before soem core members decided
to delete part of the support code for no apparent reason.
However there are some new design criteria that need to be considered
that the old devfs didn't consider. (that is why one makes a prototype,
so that one learns what is important).
For example, it turns out that one of the
important items a devfs needs to take into account is the ability for
an operator to populate chroot/jail regions with a subset of devices.
Puting a mountpoint for a devfs on each jail (there could be
thousands) is not a winning solution. This suggests that the base
filesystem needs to be involved in some way.
Also the probing of new devices and disk partitions as they are
loaded and created can be problematic. (that is what the deleted
code did). I am now of the opinion that there needs to be a kernel
devd which is responsible for probing out new partition hierarchies
(with it's own context), and other actions within the devfs. it is even
possible, given Poul-henning's device nodes within the kernel
that much of the functionality that is looked for with devfs
can be achieved via other means.
Certainly the whole concept is up for discussion.
>
> bp@ has a non-working prototype, (as has julian@).
>
> None of them fixes the root-mount kludges.
actually the code you and SOS delted DID solve that....
>
> None of them implement cloning devices.
no, though have you tried looking at ptys under devfs..
as you use them, more are created.. (a bit of a hack but kinda cute).
>
> If you (or a group of people) seriously want to work on DEVFS, send
> me an email and I will coordinate and try to make sure we get this
> done *right* so that we cover all the issues we need to cover with
> devfs (root-mount, jail, cloning etc etc)
Of better still email me too.
>
> --
> Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
> phk@FreeBSD.ORG | TCP/IP since RFC 956
> FreeBSD coreteam member | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
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--
__--_|\ Julian Elischer
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( OZ ) World tour 2000
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