Re: devfs and /proc/ide/hda

From: AJ Lewis (lewis@sistina.com)
Date: Fri Apr 27 2001 - 11:09:36 EST

On Thu, Mar 08, 2001 at 01:32:03PM +0100, Goswin Brederlow wrote:
> > What it should do is change based on whether devfs is mounted
> > or not. It doesn't make *any* sense to have
> > /dev/ide/host0/foo/bar in your /proc/partitions entries if you
> > aren't mounting devfs. The /proc/partitions entry is the only
> > way I know of for something like LVM to determine which devices
> > to scan for Volume Groups. If you can't read /proc/partitions,
> > it has to attempt to scan all block devices it recognizes,
> > regardless of whether they are actually on the system or not.
> > This can take several minutes.
>
> First:
>
> % cat /proc/partitions
> major minor #blocks name
>
> 3 0 20010816 ide/host0/bus0/target0/lun0/disc
> 3 1 192748 ide/host0/bus0/target0/lun0/part1
> 3 2 249007 ide/host0/bus0/target0/lun0/part2
> 3 3 1 ide/host0/bus0/target0/lun0/part3
> 3 5 289138 ide/host0/bus0/target0/lun0/part5
> 3 6 1951866 ide/host0/bus0/target0/lun0/part6
> 3 7 979933 ide/host0/bus0/target0/lun0/part7
> 3 8 16346106 ide/host0/bus0/target0/lun0/part8
> 33 0 80043264 ide/host2/bus0/target0/lun0/disc
> 33 1 80035798 ide/host2/bus0/target0/lun0/part1
>
> So its already right.

Only if devfs is mounted. That's my point. Maybe it's an corner case to
have devfs compiled into the kernel, but not mounted, and so we can just
ignore this, but it seems to me that /proc/partitions should reflect which
/dev system is currently running.

> Secondly with devfs, why not just scan all /dev/discs/?
>
> % ls -l /dev/discs
> total 0
> lr-xr-xr-x 1 root root 30 Jan 1 1970 disc0 -> ../ide/host0/bus0/target0/lun0/
> lr-xr-xr-x 1 root root 30 Jan 1 1970 disc1 -> ../ide/host2/bus0/target0/lun0/
>
> Also if lvm opens all known devices by way of /dev/whatever while
> scanning, it will only find existing devices there with devfs.

Yeah, as long as devfs is running, that makes sense. 

-- 
AJ Lewis
Sistina Software Inc.                  Voice:  612-379-3951
1313 5th St SE, Suite 111              Fax:    612-379-3952
Minneapolis, MN 55414                  E-Mail: lewis@sistina.com
http://www.sistina.com

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