Re: Modules and DevFS

Michael B. Trausch (fd0man@crosswinds.net)
Tue, 30 Jan 2001 17:20:41 -0500 (EST)


On Wed, 31 Jan 2001, William Knop wrote:
>
> Correct me if I'm wrong, but DevFS only makes /dev entries when a device is
> present, and the device is not present until the module is loaded. So if I
> want to access /dev/hda and the IDE module has not been loaded yet, I will
>

One thing that I've noticed with devfs is that all the old-style names are
symlinks. Documentation/filesystems/devfs/README, I think is the file
that describes this. The actual device file for /dev/hda now is:

/dev/ide/hd/c0b0t0u0

OR

/dev/ide/host0/bus0/target0/lun0/disc

I use the shorter one in my fstab, it makes things neater. It's also a
symlink, but I would think that symlink will stay longer than /dev/hda
will, anyway. When I rebuild my system, or get a completely new one,
everything will probably wind up using /dev/ide/host0... etc.

>
> I realize modularizing the entire IDE subsystem is not really good anyway,
> because every time it reloads it will rescan the bus... But what about USB?
> Suppose I don't have any IDE or USB devices, but want support so I can use
> them later. Especially in the case of USB, plugability is a must for desktop
> "home" systems.
>

Everything is modularized here, including ppp and such, and modprobe is
loading everything quite nicely for me. I don't like to run one big
kernel, it wastes too much memory, and so I use pretty much *everything*
that I can in modules (IDE I can't, because I boot from IDE, but I leave
SCSI in a module, becuase I use ide-scsi to burn my CDs and it's not
*reqired*).

[clipped]
>
> I read all the FAQs and stuff and found nothing that really addresses this,
> so here I ask if anyone has any idea as to a solution. No doubt I screwed
> something up somewhere along the line... If my kernel or XF86 config files
> are needed, I can pull 'em up and post 'em. Also, please CC responses to me
> because I'm not currently subscribed.
>

I can't help you much more than what I've already said, but best of wishes
and luck to you. I would advise that you traverse through /dev/ though,
and find out how the new organization is... it's *quite* different from
the old method. The symlinks are only there for backwards compatability
for the time being - however, I'd expect those to be moved out when pretty
much all Linux software is using the new arrangement.

- Mike

===========================================================================
Michael B. Trausch fd0man@crosswinds.net
Avid Linux User since April, '96! AIM: ML100Smkr

Contactable via IRC (DALNet) or AIM as ML100Smkr
===========================================================================

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/