Date: Wed, 3 Jun 1998 14:36:57 +0400 (MSD) From: bag@sinbin.demos.su (Alex G. Bulushev) To: bag@sinbin.demos.su (Alex G. Bulushev) Cc: mike@smith.net.au, tlambert@primenet.com, eivind@yes.no, sepotvin@videotron.ca, current@FreeBSD.ORG Subject: Re: I see one major problem with DEVFS... Message-ID: <199806031036.OAA27314@sinbin.demos.su> In-Reply-To: <199806030915.NAA15706@sinbin.demos.su> from "Alex G. Bulushev" at "Jun 3, 98 01:15:14 pm"
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> on nfs client we have:
>
> {nfs_clnt1}# mount
> /dev/sd0s1a on / (local, noatime, writes: sync 6436172 async 3495235))
> procfs on /proc (local)
> nfs_srv:/mnt/roots on /mnt/roots
> {nfs_clnt1}# ls -al /mnt/roots/VM1/dev/null
> crw-rw-rw- 1 root weel 2, 2 3 jun 14:27 /mnt/roots/VM1/dev/null
> ^^^^^^^^^^^ time from nfs_srv
> {nfs_clnt1}# chroot /mnt/roots/VM1 /bin/cat /etc/passwd > /dev/null
sorry, correct demonstration is:
{nfs_clnt1}# ls -al /mnt/roots/VM1/dev/null
crw-rw-rw- 1 root wheel 2, 2 3 jun 14:27 /mnt/roots/VM1/dev/null
{nfs_clnt1}# chroot /mnt/roots/VM1 /bin/sh
# /bin/cat /etc/passwd > /dev/null
# exit
{nfs_clnt1}# ls -al /mnt/roots/VM1/dev/null
crw-rw-rw- 1 root wheel 2, 2 3 jun 14:28 /mnt/roots/VM1/dev/null
^^^^^^^^^^^ time changed
{nfs_clnt1}# ls -al /dev/null
crw-rw-rw- 1 root wheel 2, 2 3 jun 14:28 /dev/null
^^^^^^^^^^^ time changed
{nfs_clnt1}#
>
>
> so we use "nfs mounted devices" localy on nfs clients
> surely local major/minor for devices mast by the same as on the remote server
> or u mast use device proxy on fs level (not existing now)
>
> with "classic" device nodes on file systems it is realy simple
> to use this scheme
>
> with dynamic device id and devices only on devfs mounted, it is very hard
> to use devices on nfs, especially if u have several nfs clients vith handreds
> of chrooted "virtual mashines", a lot of mount/unmont devfs and rm/mknod in
> boot time and before/after of delete/create each VM and on each nfs
> server/client kill u system and require a number of custom scripts and
> sync of all manipulation via network (using rsh or other tools)
>
> >
> > > For normal devices that are only operated on via open/close/read/write,
> > > it makes sens to export a devfs.
> >
> > No, it does not. There is no identifying information exported with a
> > DEVFS node that allows the local system to correctly connect a node
> > from a remote DEVFS (which may not map to a local driver) to a local
> > device.
> >
> > > This isn't as useful as the true proxy provided by OpenNET, but it's
> > > a good step in that direction.
> >
> > You want to proxy device accesses to devices on the exporting system.
> > That's a completely different kettle of fish entirely.
> >
> > --
> > \\ Sometimes you're ahead, \\ Mike Smith
> > \\ sometimes you're behind. \\ mike@smith.net.au
> > \\ The race is long, and in the \\ msmith@freebsd.org
> > \\ end it's only with yourself. \\ msmith@cdrom.com
> >
> >
> >
> > To Unsubscribe: send mail to majordomo@FreeBSD.org
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> >
>
>
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