questions about udev...beginner

questions about udev...beginner

[linuxcbon]

Hi,

I am not familiar with udev and didn't find a good enough howto.
So I ask you questions, thank you for your kind help in advance.

I have put this in rc.sysinit :
/sbin/udevd --daemon
/sbin/udevadm trigger
/sbin/modoprobe many modules....
/sbin/udevadm settle
is it the correct way of doing this ?

Another question is :
Do I need rules in /etc/udev  ? Or not needed , automagical ?

Best regards 

Re: questions about udev...beginner

[Tom Gundersen]

On Mon, Sep 12, 2011 at 9:07 AM, linuxcbon <linuxcbon@yahoo.fr> wrote:
> I am not familiar with udev and didn't find a good enough howto.
> So I ask you questions, thank you for your kind help in advance.

This is how we do it in Arch:
<http://projects.archlinux.org/initscripts.git/tree/functions#n311>.

> I have put this in rc.sysinit :
> /sbin/udevd --daemon
> /sbin/udevadm trigger

You probably want
  /sbin/udevadm trigger --action­d --type=subsystems
  /sbin/udevadm trigger --action­d --typeÞvices
instead (the default is only --typeÞvices, and not --type=subsystems).

> /sbin/modoprobe many modules....
> /sbin/udevadm settle
> is it the correct way of doing this ?

Looks good except for the missing subsystems bit.

> Another question is :
> Do I need rules in /etc/udev  ? Or not needed , automagical ?

You should not need any rules in /etc/udev, the standard ones shipped
in /lib/udev should be sufficient.

Cheers,

Tom

Re: questions about udev...beginner

[William Hubbs]

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Hi Tom and all,

On Mon, Sep 12, 2011 at 09:27:50AM +0200, Tom Gundersen wrote:
> On Mon, Sep 12, 2011 at 9:07 AM, linuxcbon <linuxcbon@yahoo.fr> wrote:
> > I am not familiar with udev and didn't find a good enough howto.
> > So I ask you questions, thank you for your kind help in advance.
> 
> This is how we do it in Arch:
> <http://projects.archlinux.org/initscripts.git/tree/functions#n311>.
> 
> > I have put this in rc.sysinit :
> > /sbin/udevd --daemon
> > /sbin/udevadm trigger
> 
> You probably want
>   /sbin/udevadm trigger --action=add --type=subsystems
>   /sbin/udevadm trigger --action=add --type=devices
> instead (the default is only --type=devices, and not --type=subsystems).
 
Now I need clarification. The README shipped with udev does not mention
"--action=add". According to that file, you just want

/sbin/udevadm trigger --type=subsystems
/sbin/udevadm trigger --type=devices

Which is correct?

Thanks,

William


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Re: questions about udev...beginner

[Allin Cottrell]

On Mon, 12 Sep 2011, William Hubbs wrote:

> Hi Tom and all,
>
> On Mon, Sep 12, 2011 at 09:27:50AM +0200, Tom Gundersen wrote:
>> On Mon, Sep 12, 2011 at 9:07 AM, linuxcbon <linuxcbon@yahoo.fr> wrote:
>>> I am not familiar with udev and didn't find a good enough howto.
>>> So I ask you questions, thank you for your kind help in advance.
>>
>> This is how we do it in Arch:
>> <http://projects.archlinux.org/initscripts.git/tree/functions#n311>.
>>
>>> I have put this in rc.sysinit :
>>> /sbin/udevd --daemon
>>> /sbin/udevadm trigger
>>
>> You probably want
>>   /sbin/udevadm trigger --action­d --type=subsystems
>>   /sbin/udevadm trigger --action­d --typeÞvices
>> instead (the default is only --typeÞvices, and not --type=subsystems).
>
> Now I need clarification. The README shipped with udev does not mention
> "--action­d". According to that file, you just want
>
> /sbin/udevadm trigger --type=subsystems
> /sbin/udevadm trigger --typeÞvices
>
> Which is correct?

Well the latter works fine here, with udev 173.

Allin Cottrell

Re: questions about udev...beginner

[Tom Gundersen]

On Mon, Sep 12, 2011 at 3:56 PM, William Hubbs <w.d.hubbs@gmail.com> wrote:
> Now I need clarification. The README shipped with udev does not mention
> "--action­d". According to that file, you just want
>
> /sbin/udevadm trigger --type=subsystems
> /sbin/udevadm trigger --typeÞvices
>
> Which is correct?

I guess Kay could answer this with more authority. But I'm pretty
certain --type­d is correct.

Have a look in init/udev-trigger.service.in to see how udev behaves
when used with systemd (it uses "add").

Also, when that section of the README was written, --type­d was the
default, but that later changed to --type=change, so it looks like it
is just out of date.

Cheers,

Tom

Re: questions about udev...beginner

[linuxcbon]

Hi,

> I guess Kay could answer this with more authority. But I'm
> pretty
> certain --type≠d is correct.

You mean --action≠d

> Also, when that section of the README was written,
> --type≠d was the
> default, but that later changed to --type=change, so it
> looks like it
> is just out of date.

udevadm trigger --help says : default for action is "change" 

So you mean ?
udevadm trigger --typefivices --action≠d
udevadm trigger --type=subsystems --action≠d

Thanks.


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Re: questions about udev...beginner

[Tom Gundersen]

On Mon, Sep 12, 2011 at 6:57 PM, linuxcbon <linuxcbon@yahoo.fr> wrote:
>> I guess Kay could answer this with more authority. But I'm
>> pretty
>> certain --type­d is correct.
>
> You mean --action­d

Yes, sorry.

>> Also, when that section of the README was written,
>> --type­d was the
>> default, but that later changed to --type=change, so it
>> looks like it
>> is just out of date.
>
> udevadm trigger --help says : default for action is "change"

Exactly. It used to be "add".

> So you mean ?
> udevadm trigger --typeÞvices --action­d
> udevadm trigger --type=subsystems --action­d

Indeed (as in my original email).

-t

Re: questions about udev...beginner

[Kay Sievers]

On Mon, Sep 12, 2011 at 19:09, Tom Gundersen <teg@jklm.no> wrote:
> On Mon, Sep 12, 2011 at 6:57 PM, linuxcbon <linuxcbon@yahoo.fr> wrote:
>>> I guess Kay could answer this with more authority. But I'm
>>> pretty
>>> certain --type­d is correct.
>>
>> You mean --action­d
>
> Yes, sorry.
>
>>> Also, when that section of the README was written,
>>> --type­d was the
>>> default, but that later changed to --type=change, so it
>>> looks like it
>>> is just out of date.
>>
>> udevadm trigger --help says : default for action is "change"
>
> Exactly. It used to be "add".
>
>> So you mean ?
>> udevadm trigger --typeÞvices --action­d
>> udevadm trigger --type=subsystems --action­d

Classic system 'coldplug' replays the missing events which happened
before userspace was ready to receive them. We usually use 'add' here
because that is what the original event, which we missed, was.

No other other use case, should ever use 'add', only 'change' is
appropriate when the system is already running.

The systemd service files in the udev source tree always reflect the
current way of doing coldplug.

Kay