Messages in this thread | | | Date | Wed, 28 Mar 2001 02:03:01 +0100 (IST) | From | Paul Jakma <> | Subject | Re: Larger dev_t |
| |
On Tue, 27 Mar 2001, Dan Hollis wrote:
> On Tue, 27 Mar 2001, H. Peter Anvin wrote: > > c) Make sure chown/chmod/link/symlink/rename/rm etc does the right thing, > > without the need for "tar hacks" or anything equivalently gross. > > write-through filesystem, like overlaying a r/w ext2 on top of an iso9660 > fs.
functionality to do this is in devfs and devfsd already.
there are 2 ways:
1. devfs on /dev, maintain state in /dev-state. 2. regular ext2 (devfs naming style) /dev and devfs mounted on, eg, /devfs for hotplug and module load/unload updates
1:
/dev-state -> regular ext2 /dev -> devfs
use the CREATE, CHANGE and REGISTER hooks that devfs has to allow devfsd to transparently copy changes in /dev to the ext2 /dev-state. See the example devfsd.conf for appropriate entries, eg:
REGISTER .* COPY /dev-state/$devname $devpath CHANGE .* COPY $devpath /dev-state/$devname CREATE .* COPY $devpath /dev-state/$devname
2:
/dev -> regular ext2 /devfs -> devfs
use the devfs hooks for REGISTER and UNREGISTER to have devfsd update the static /dev whenever hotplug events occur. Eg:
REGISTER .* COPY ${mntpnt}/$devname /dev/$devname UNREGISTER .* CFUNCTION GLOBAL unlink /dev/$devname
seems to work for me:
[root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram ls: /dev/misc/nvram: No such file or directory ls: /devfs/misc/nvram: No such file or directory [root@fogarty /devfs]# modprobe nvram [root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram crw-r----- 1 root root 10, 144 Jan 1 1970 /devfs/misc/nvram crw-r----- 1 root root 10, 144 Mar 28 01:56 /dev/misc/nvram [root@fogarty /devfs]# rmmod nvram [root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram ls: /dev/misc/nvram: No such file or directory ls: /devfs/misc/nvram: No such file or directory
> -Dan
i prefer option 2 as /dev state is then not dependent on devfsd being there and it just sidesteps the whole permissions issue. if devfsd doesn't start then i still have a fully functional /dev.
but anyway... there seems to be loads of scope to do lots of different things with devfsd, plus NIS support. :)
regards, -- Paul Jakma paul@clubi.ie paul@jakma.org PGP5 key: http://www.clubi.ie/jakma/publickey.txt ------------------------------------------- Fortune: Premature optimization is the root of all evil. -- D.E. Knuth
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |