Re: 2.6.0-test1 devfs question

From: Wiktor Wodecki <wodecki@gmx.de>
To: Balram Adlakha <b_adlakha@softhome.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.6.0-test1 devfs question
Date: Sat, 26 Jul 2003 12:45:06 +0200	[thread overview]
Message-ID: <20030726104506.GA663@gmx.de> (raw)
In-Reply-To: <20030725185325.GA3944@localhost.localdomain>

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On Sat, Jul 26, 2003 at 12:23:25AM +0530, Balram Adlakha wrote:
> >Hello,
> 
> >I'm currently running at 2.6.0-test1-mm2-O8 and I wanted to give devfs a
> >shot. I recompiled the kernel with the following settings:
> >CONFIG_DEVFS_FS=y
> >CONFIG_DEVFS_MOUNT=y
> ># CONFIG_DEVFS_DEBUG is not set
> 
> >As I read through the documentation (btw, devfs=nomount is mentioned in
> >configure help but not in Documentation/filesystems/devfs/boot-options)
> >I got the understanding that this shouldn't make any difference to the
> >system right? After booting with this kernel there were lots of proper
> >devfs devices in my dmesg (host0/ide0... scsi0/...) however, the system
> >didn't came up (couldn't mount rootfs). It didn't even work when I
> >enabled CONFIG_DEVFS_MOUNT.
> 
> >I'm not sure whether this is a bug in mount/nomount of devfs or if it's
> >somewhere my fault/setup (root on raid1, various lvm2 devices on raid1/0
> >devices)
> 
> >Any help would be greatly appreciated.
> 
> 
> You need to change your /etc/fstab to reflect the new devfs device names,
> ex: "/dev/discs/disc0/part1" instead of "/dev/hda1". You can also use devfsd (or some alternative) to make synlinks to the older devices and retain permissions etc... Also, without devfsd you cannot expect module autoloading as modules can't be automatically loaded when theres no device requesting them (in this case the device simply doesn't exist until module is loaded)

wait a second, this is a dumb thing to do. I do not want to migrate over
to devfs yet. I wanted to give it a shot and look around a bit. What I
haad in mind was mounting it on /dev2 or similar. Enabling this option
and converting my whole system is not a migration path. That's just
plain luck (might be easy for plain ide/scsi disks, but whatabout
metadevices like lvm and raid?). It is written in the documentation that
devfs comes with most backwards compatibility. I expected there to be
things like /dev/md0 and such for compatibility.
OTOH what's CONFIG_DEVFS_MOUNT for then? If devices get named the other
way round I *have* to mount it anyway, haven't I? I think improvements
must happen here in order to make devfs usable.

-- 
Regards,

Wiktor Wodecki

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