Changing over to udev

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Changing over to udev

David Baron
If, indeed, this must be done--this provides hotplug functionality as well.

Does it need to be in control? As of now, many things are modprobed before
hotplug and hotplug says "already loaded". Might be quite difficult to find
and sort all this out. Hotplug/udev might be self-sufficient
without /etc/modules or alsa configuration scripts elsewhere but maybe not.

Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and 2.6.14 (which
must have udev). Until 2.6.14 is demonstrably working with udev, I do not
want to get rid of 2.6.11 (which uses devfs and current hotplug). Can udev be
installed anyway? Consequences?


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Re: Changing over to udev

Jacob S
On Wed, 14 Dec 2005 23:00:04 +0200
David Baron <[hidden email]> wrote:

> If, indeed, this must be done--this provides hotplug functionality as
> well.
>
> Does it need to be in control? As of now, many things are modprobed
> before hotplug and hotplug says "already loaded". Might be quite
> difficult to find and sort all this out. Hotplug/udev might be
> self-sufficient without /etc/modules or alsa configuration scripts
> elsewhere but maybe not.
>
> Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and
> 2.6.14 (which must have udev). Until 2.6.14 is demonstrably working
> with udev, I do not want to get rid of 2.6.11 (which uses devfs and
> current hotplug). Can udev be installed anyway? Consequences?

I'm currently trying to learn/convert to udev on Sid as well. What I did
was to install the 2.6.12 kernel which can also work without udev.
2.6.12 is currently in Testing.

HTH,
Jacob


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Re: Changing over to udev

David Zelinsky
In reply to this post by David Baron
David Baron <[hidden email]> writes:

> Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and 2.6.14 (which
> must have udev).

When I upgraded from 2.4 kernel to 2.6.14 I also installed udev along
the way -- I don't remember why.  But I later removed udev because
some device files weren't getting created properly and I couldn't
understand how to fix it.  Now everything seems to work fine without
udev, using plain old static device files.  Am I missing something?  I
am running Sarge not Sid; maybe that's the difference?

-David


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Re: Changing over to udev

Marc Wilson
In reply to this post by David Baron
On Wed, Dec 14, 2005 at 11:00:04PM +0200, David Baron wrote:
> Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and 2.6.14 (which
> must have udev). Until 2.6.14 is demonstrably working with udev, I do not
> want to get rid of 2.6.11 (which uses devfs and current hotplug). Can udev be
> installed anyway? Consequences?

rei $ uname -a
Linux rei 2.6.14.2 #1 PREEMPT Mon Nov 21 09:50:55 PST 2005 i686 GNU/Linux

And I'm using udev on this box.  Not that I like it, not that I give a
tinker's damn about demonstrating how big my d*ck is by how empty I can
make /dev (and that emptiness has meant I've had to write rules for every
symlink I ever had in there)... I just wanted persistent naming for four
external USB hard disk enclosures.

And I more or less had to use udev to do it.  That's unfortunate.  I *so*
wish md would actually follow through on his claims and demonstrate how to
use udev with a static /dev.

Oh, and that's a self-built 2.6.14.2... FWIW the last thing I'd ever do is
use a Debian kernel.

--
 Marc Wilson |     Q: What's the difference between a duck and an
 [hidden email] |     elephant?  A: You can't get down off an elephant.


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Re: Changing over to udev

Jacob S
In reply to this post by David Zelinsky
On 14 Dec 2005 22:41:27 -0500
David Zelinsky <[hidden email]> wrote:

> David Baron <[hidden email]> writes:
>
> > Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and
> > 2.6.14 (which must have udev).
>
> When I upgraded from 2.4 kernel to 2.6.14 I also installed udev along
> the way -- I don't remember why.  But I later removed udev because
> some device files weren't getting created properly and I couldn't
> understand how to fix it.  Now everything seems to work fine without
> udev, using plain old static device files.  Am I missing something?  I
> am running Sarge not Sid; maybe that's the difference?

The difference is that you can write rules for udev so that it will
always symlink, for example, your usb pendrive to /dev/pendrive and
your usb camera to /dev/webcam. This keeps you from having to look
at /var/log/syslog after you plugin each one to figure out which device
name it was assigned this time (if I plug in my pendrive first,
it's /dev/sdb, but if I plug in the camera and then the pendrive,
it's /dev/sdc, etc.). And then if you have to change the preferences
for your software each time you plug in the device so that it knows
where to find it... you get the idea.

Plain old static device files can still work, udev is just a nice
convenience that makes life easier.

HTH,
Jacob


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Re: Changing over to udev

Carl Fink-2
On Wed, Dec 14, 2005 at 11:29:17PM -0600, Jacob S wrote:

> Plain old static device files can still work, udev is just a nice
> convenience that makes life easier.

... or would be if it actually worked.
--
Carl Fink                                         [hidden email]
   "Patriotism is supporting your country all the time, and your
   government when it deserves it."
                      - Mark Twain


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Re: Changing over to udev

Hugo Vanwoerkom
In reply to this post by Marc Wilson
Marc Wilson wrote:

> On Wed, Dec 14, 2005 at 11:00:04PM +0200, David Baron wrote:
>
>>Udev on Sid requires 2.6.12 or newer kernels. I have 2.6.11 and 2.6.14 (which
>>must have udev). Until 2.6.14 is demonstrably working with udev, I do not
>>want to get rid of 2.6.11 (which uses devfs and current hotplug). Can udev be
>>installed anyway? Consequences?
>
>
> rei $ uname -a
> Linux rei 2.6.14.2 #1 PREEMPT Mon Nov 21 09:50:55 PST 2005 i686 GNU/Linux
>
> And I'm using udev on this box.  Not that I like it, not that I give a
> tinker's damn about demonstrating how big my d*ck is by how empty I can
> make /dev (and that emptiness has meant I've had to write rules for every
> symlink I ever had in there)... I just wanted persistent naming for four
> external USB hard disk enclosures.
>
> And I more or less had to use udev to do it.  That's unfortunate.  I *so*
> wish md would actually follow through on his claims and demonstrate how to
> use udev with a static /dev.
>
> Oh, and that's a self-built 2.6.14.2... FWIW the last thing I'd ever do is
> use a Debian kernel.
>

The reason being?

H


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Re: Changing over to udev

Colin-30
In reply to this post by Carl Fink-2
Carl Fink wrote:
> On Wed, Dec 14, 2005 at 11:29:17PM -0600, Jacob S wrote:
>
>
>>Plain old static device files can still work, udev is just a nice
>>convenience that makes life easier.
>
>
> ... or would be if it actually worked.

Works great for me!


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Re: Changing over to udev

seeker5528 (Bugzilla)
In reply to this post by Marc Wilson
On Wed, 14 Dec 2005 19:45:03 -0800
Marc Wilson <[hidden email]> wrote:

> And I'm using udev on this box.  Not that I like it, not that I give a
> tinker's damn about demonstrating how big my d*ck is by how empty I can
> make /dev (and that emptiness has meant I've had to write rules for every
> symlink I ever had in there)... I just wanted persistent naming for four
> external USB hard disk enclosures.

I'm not really understanding what this issue with symlinks is?

On the rare occasion I have poked around with rules udev
was easier to figure out for me than devfs was.

The issue with recent kernels where you can't predict which network
card will be initialized first and get eth0 and you need a specific
card to be eth0. The list archive shows a pretty handy solution using
a udev rule.

I have not had to create a symlink for any hardware
devices /dev/dsp, /dev/adsp, /dev/hdX, /dev/sdX, /dev/video0, etc...
all show up without me having to do a thing.

I had a DVD drive as my only CD type device and for it I
had /dev/cdrom, /dev/dvd, and /dev/hdd showing up in /dev. Recently I
replaced it with a DVD burner and automagically I now also
have /dev/cdrw that shows up, didn't have to do a thing.

Later, Seeker


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Re: Re: Changing over to udev

Jim McCloskey
In reply to this post by Carl Fink-2
|> > Plain old static device files can still work, udev is just a nice
|> > convenience that makes life easier.
|>
|> ... or would be if it actually worked.

What have you had trouble with?

I have 2.6.14.4 and udev 076 from testing and everything just worked (on
2 desktops and a laptop) with no interference from me. I wrote udev rules
for a camera and 2 pendrives, but that wasn't exactly hard, and udev has
made using those enormously easier.
 
One of the things that I appreciate it is the way I can plug in
a USB soundcard and the right module is instantly loaded and the right
device files are created in /dev/snd/. I just don't have to think about
any of it.

Jim


 


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