udev/hotplug success story

udev/hotplug success story

[Daniel Drake]

Hi Greg,

Thought you might be interested to know that I've got my setup working great 
with udev controlling /dev.

I'm running a gentoo based system, kernel 2.6.2-mm1, udev 016, hotplug 20040105

A few comments:

With the default devfs-like config, udev correctly places a symlink to 
/dev/hdc as /dev/cdroms/cdrom0.
With devfs, I had it setup so that I could also use /dev/dvd there. Writing a 
rule for udev to do that is no problem. I told it to name the device "hdc" and 
SYMLINK "dvd". The only thing there, is that it then overwrote the devfs-like 
rule, and /dev/cdroms/cdrom0 no longer existed. In the end I just added 
another SYMLINK to cdroms/cdrom0, but I was wondering, is there a better way - 
are there rules that I can pass that append SYMLINKs onto other ones?


Hotplug is doing a good job of managing my usb modules. When I plug my camera 
in, it loads usb-storage as expected. However, it doesnt load sd_mod, meaning 
that no /dev/sda1 is created, and I can't access my pictures.

I could easily get around this by writing a script to "modprobe sd_mod", and 
then adding a line to /etc/hotplug/usb.usermap.

To better fit in with the purpose of hotplugging, I would think that this 
module should be loaded automatically after usb-storage. Is this a 
bug/missing-feature, or intentional?


Final comment: I think that the documentation for hotplug is a little lacking. 
In particular, I had trouble finding out what the match_flags column in 
usb.usermap does, I eventually found the answer by looking through the code of 
usb.agent


cheers,

Daniel


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Re: udev/hotplug success story

[Måns Rullgård]

Daniel Drake <dan@reactivated.net> writes:

> Hotplug is doing a good job of managing my usb modules. When I plug my
> camera in, it loads usb-storage as expected. However, it doesnt load
> sd_mod, meaning that no /dev/sda1 is created, and I can't access my
> pictures.

It used to load sd-mod automatically for me, but stopped some time
around 2.6.2-rc1.

> I could easily get around this by writing a script to "modprobe
> sd_mod", and then adding a line to /etc/hotplug/usb.usermap.
>
> To better fit in with the purpose of hotplugging, I would think that
> this module should be loaded automatically after usb-storage. Is this
> a bug/missing-feature, or intentional?

Hacking modprobe.conf to get that behavior is trivial.

-- 
Måns Rullgård
mru@kth.se



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Re: udev/hotplug success story

[Patrick Mansfield]

On Mon, Feb 09, 2004 at 12:50:50AM +0100, Måns Rullgård wrote:
> Daniel Drake <dan@reactivated.net> writes:
> 
> > Hotplug is doing a good job of managing my usb modules. When I plug my
> > camera in, it loads usb-storage as expected. However, it doesnt load
> > sd_mod, meaning that no /dev/sda1 is created, and I can't access my
> > pictures.
> 
> It used to load sd-mod automatically for me, but stopped some time
> around 2.6.2-rc1.

We could race looking for the sys attribute type in scsi.agent.

That is scsi attributes are added after the hotplug is invoked.

Is there anything in your log file from scsi.agent? Like this one:

	mesg "how to add device type=$TYPE at $DEVPATH ??"

If so, try adding a sleep 1 in scsi.agent just before the cat of type,
i.e.:

	sleep 1
	TYPE=$(cat /sys/$DEVPATH/type)

-- Patrick Mansfield


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Re: udev/hotplug success story

[Greg KH]

On Sun, Feb 08, 2004 at 09:11:16PM +0000, Daniel Drake wrote:
> 
> Final comment: I think that the documentation for hotplug is a little 
> lacking. In particular, I had trouble finding out what the match_flags 
> column in usb.usermap does, I eventually found the answer by looking 
> through the code of usb.agent

I agree, although a user should never have to muck around with those
files, use the automatically generated ones :)

But if you want to write something up, I'd be glad to add it to the
package.

thanks,

greg k-h


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Re: udev/hotplug success story

[Greg KH]

On Sun, Feb 08, 2004 at 09:11:16PM +0000, Daniel Drake wrote:
> 
> Hotplug is doing a good job of managing my usb modules. When I plug my 
> camera in, it loads usb-storage as expected. However, it doesnt load 
> sd_mod, meaning that no /dev/sda1 is created, and I can't access my 
> pictures.

This is bug in the current release of the hotplug scripts.  A fix for
this has been posted to the mailing list.

thanks,

greg k-h


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