how to do ? minimal udev script for my rc.sysinit ?

how to do ? minimal udev script for my rc.sysinit ?

[linuxcbon linuxcbon]

Hi,

my kernel boots ok and gives the hand to init which runs rc.sysinit.
I am writing a minimal rc.sysinit.
It creates /dev with devtmpfs and now all works except udev.
I need 1 or 2 or 3 lines with udev commands to make it work
and detect and modprobe needed modules.
I don't know the minimal and shortest commands to do this ?
Can you please help me ?

Thanks in advance.
Linuxcbon

Re: how to do ? minimal udev script for my rc.sysinit ?

[Greg KH]

On Tue, May 05, 2015 at 09:27:38PM +0000, linuxcbon linuxcbon wrote:
> Hi,
> 
> my kernel boots ok and gives the hand to init which runs rc.sysinit.
> I am writing a minimal rc.sysinit.
> It creates /dev with devtmpfs and now all works except udev.
> I need 1 or 2 or 3 lines with udev commands to make it work
> and detect and modprobe needed modules.
> I don't know the minimal and shortest commands to do this ?
> Can you please help me ?

Try using mdev.

Re: how to do ? minimal udev script for my rc.sysinit ?

[linuxcbon linuxcbon]

On Tue, May 5, 2015 at 10:34 PM, Greg KH <greg@kroah.com> wrote:
> On Tue, May 05, 2015 at 09:27:38PM +0000, linuxcbon linuxcbon wrote:
>> Hi,
>>
>> my kernel boots ok and gives the hand to init which runs rc.sysinit.
>> I am writing a minimal rc.sysinit.
>> It creates /dev with devtmpfs and now all works except udev.
>> I need 1 or 2 or 3 lines with udev commands to make it work
>> and detect and modprobe needed modules.
>> I don't know the minimal and shortest commands to do this ?
>> Can you please help me ?
>
> Try using mdev.


Hi Greg,

I already do this "mount -t devtmpfs dev /dev" which automagically
creates /dev files
When I do a "mdev -s" , it will recreate /dev, so what's the point of
using devtmpfs
I am also not sure if mdev triggers modprobes like udev does ?
If you have some working mdev or udev examples, I will try.
Until now, this problem has been a real pain for me...

Thanks.
linuxcbon

Re: how to do ? minimal udev script for my rc.sysinit ?

[Tom Gundersen]

On Tue, May 5, 2015 at 11:27 PM, linuxcbon linuxcbon
<linuxcbon@gmail.com> wrote:
> my kernel boots ok and gives the hand to init which runs rc.sysinit.
> I am writing a minimal rc.sysinit.
> It creates /dev with devtmpfs and now all works except udev.
> I need 1 or 2 or 3 lines with udev commands to make it work
> and detect and modprobe needed modules.
> I don't know the minimal and shortest commands to do this ?
> Can you please help me ?

A good starting point is to look at the ExecStart lines in the udev
service files used by systemd. You'll likely want to pass --daemon to
the main daemon though so that it will fork to the background:

http://cgit.freedesktop.org/systemd/systemd/tree/units/systemd-udevd.service.in
http://cgit.freedesktop.org/systemd/systemd/tree/units/systemd-udev-trigger.service.in
http://cgit.freedesktop.org/systemd/systemd/tree/units/systemd-udev-settle.service.in

(note that the order matters).

Apart from that I don't think anyone is using/testing/developing for
this setup any longer, so you are mostly on your own, sorry.

HTH,

Tom

Re: how to do ? minimal udev script for my rc.sysinit ?

[Robert Milasan]

On Tue, 5 May 2015 21:27:38 +0000
"linuxcbon linuxcbon" <linuxcbon@gmail.com> wrote:

> Hi,
> 
> my kernel boots ok and gives the hand to init which runs rc.sysinit.
> I am writing a minimal rc.sysinit.
> It creates /dev with devtmpfs and now all works except udev.
> I need 1 or 2 or 3 lines with udev commands to make it work
> and detect and modprobe needed modules.
> I don't know the minimal and shortest commands to do this ?
> Can you please help me ?
> 
> Thanks in advance.
> Linuxcbon
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-hotplug" in the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

This might help:

# start udev daemon (udevd might be called systemd-udevd)
/path/to/udevd --daemon || echo "udev error" >&2

# trigger events
/path/to/udevadm trigger --action­d || echo "udev trigger error" >&2
/path/to/udevadm trigger --type=subsystems --action­d || echo "udev trigger error" >&2

# wait for events to finish
/path/to/udevadm settle || echo "udev settle error" >&2

-- 
Robert Milasan

L3 Support Engineer
SUSE Linux (http://www.suse.com)
email: rmilasan@suse.com
GPG fingerprint: B6FE F4A8 0FA3 3040 3402  6FE7 2F64 167C 1909 6D1A

Re: how to do ? minimal udev script for my rc.sysinit ?

[linuxcbon linuxcbon]

On Wed, May 6, 2015 at 7:01 AM, Tom Gundersen <teg@jklm.no> wrote:
> A good starting point is to look at the ExecStart lines in the udev
> Tom

Hi Tom,
I don't have systemd, I have udev or mdev only.
Thanks.
linuxcbon

Re: how to do ? minimal udev script for my rc.sysinit ?

[linuxcbon linuxcbon]

On Wed, May 6, 2015 at 7:46 AM, Robert Milasan <rmilasan@suse.com> wrote:
>
> This might help:
>
> # start udev daemon (udevd might be called systemd-udevd)
> /path/to/udevd --daemon || echo "udev error" >&2
>
> # trigger events
> /path/to/udevadm trigger --action≠d || echo "udev trigger error" >&2
> /path/to/udevadm trigger --type=subsystems --action≠d || echo "udev trigger error" >&2
>
> # wait for events to finish
> /path/to/udevadm settle || echo "udev settle error" >&2
>
> --
> Robert Milasan

Hi Robert,
thanks, actually, I am testing things like that.
Do you know if I need to add a line for --typefivices and what it is for ?
Do you also know the minimal rules to have inside /lib/udev ?
I don't need to add rules inside /etc/udev ?
I also noticed udev mandatorely needs /run/udev, otherwise it doesnt start ?
thanks linuxcbon
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Re: how to do ? minimal udev script for my rc.sysinit ?

[Robert Milasan]

On Wed, 6 May 2015 18:20:56 +0100
"linuxcbon linuxcbon" <linuxcbon@gmail.com> wrote:
> 
> Hi Robert,
> thanks, actually, I am testing things like that.
> Do you know if I need to add a line for --typeÞvices and what it is

No, because --typeÞvices is the default

> for ? Do you also know the minimal rules to have inside /lib/udev ?

Depends on your hardware and what you'll in the future

> I don't need to add rules inside /etc/udev ?

No

> I also noticed udev mandatorely needs /run/udev, otherwise it doesnt
> start ? thanks linuxcbon

/run/udev is required and hardcoded in udev.


-- 
Robert Milasan

L3 Support Engineer
SUSE Linux (http://www.suse.com)
email: rmilasan@suse.com
GPG fingerprint: B6FE F4A8 0FA3 3040 3402  6FE7 2F64 167C 1909 6D1A

Re: how to do ? minimal udev script for my rc.sysinit ?

[linuxcbon linuxcbon]

On Wed, May 6, 2015 at 6:33 PM, Robert Milasan <rmilasan@suse.com> wrote:
> Depends on your hardware and what you'll in the future
> Robert Milasan

Hi Robert,
I have added your lines to sysinit.
For testing, I don't have any /etc/udev and I have an empty /lib/udev/
I get many errors with --debug , for example :
[    4.304862] udevd[77]: seq 2397 queued, 'add' 'module'
[    4.304878] udevd[81]: seq 2397 running
[    4.304890] udevd[81]: no db file to read
/run/udev/data/+module:pata_rz1000: No such file or directory
[    4.304901] udevd[81]: passed -1 bytes to netlink monitor 0x63dc00
[    4.304903] udevd[81]: seq 2397 processed with 0
[    4.304908] udevd[77]: passed 144 bytes to netlink monitor 0x62d3a0
If I understand, for each error, there must be a rule for a modprobe ? sigh...
Cheers.
linuxcbon

Re: how to do ? minimal udev script for my rc.sysinit ?

[Robert Milasan]

On Thu, 7 May 2015 02:15:51 +0100
"linuxcbon linuxcbon" <linuxcbon@gmail.com> wrote:

> Hi Robert,
> I have added your lines to sysinit.
> For testing, I don't have any /etc/udev and I have an empty /lib/udev/
> I get many errors with --debug , for example :
> [    4.304862] udevd[77]: seq 2397 queued, 'add' 'module'
> [    4.304878] udevd[81]: seq 2397 running
> [    4.304890] udevd[81]: no db file to read
> /run/udev/data/+module:pata_rz1000: No such file or directory
> [    4.304901] udevd[81]: passed -1 bytes to netlink monitor 0x63dc00
> [    4.304903] udevd[81]: seq 2397 processed with 0
> [    4.304908] udevd[77]: passed 144 bytes to netlink monitor 0x62d3a0
> If I understand, for each error, there must be a rule for a
> modprobe ? sigh... Cheers.
> linuxcbon
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-hotplug" in the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Yes, of course. You don't need udev if you don't have any rules. 

-- 
Robert Milasan

L3 Support Engineer
SUSE Linux (http://www.suse.com)
email: rmilasan@suse.com
GPG fingerprint: B6FE F4A8 0FA3 3040 3402  6FE7 2F64 167C 1909 6D1A

Re: how to do ? minimal udev script for my rc.sysinit ?

[Tom Gundersen]

On Thu, May 7, 2015 at 3:15 AM, linuxcbon linuxcbon <linuxcbon@gmail.com> wrote:
> On Wed, May 6, 2015 at 6:33 PM, Robert Milasan <rmilasan@suse.com> wrote:
>> Depends on your hardware and what you'll in the future
>> Robert Milasan
>
> Hi Robert,
> I have added your lines to sysinit.
> For testing, I don't have any /etc/udev and I have an empty /lib/udev/
> I get many errors with --debug , for example :

Debug messages are not necessarily errors, these are just information
for developers, so can be safely ignored by a user.

> [    4.304862] udevd[77]: seq 2397 queued, 'add' 'module'
> [    4.304878] udevd[81]: seq 2397 running
> [    4.304890] udevd[81]: no db file to read
> /run/udev/data/+module:pata_rz1000: No such file or directory
> [    4.304901] udevd[81]: passed -1 bytes to netlink monitor 0x63dc00
> [    4.304903] udevd[81]: seq 2397 processed with 0
> [    4.304908] udevd[77]: passed 144 bytes to netlink monitor 0x62d3a0
> If I understand, for each error, there must be a rule for a modprobe ? sigh...
> Cheers.
> linuxcbon
> --
> To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in
> the body of a message to majordomo@vger.kernel.org
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Re: how to do ? minimal udev script for my rc.sysinit ?

[Tom Gundersen]

On Wed, May 6, 2015 at 7:16 PM, linuxcbon linuxcbon <linuxcbon@gmail.com> wrote:
> On Wed, May 6, 2015 at 7:01 AM, Tom Gundersen <teg@jklm.no> wrote:
>> A good starting point is to look at the ExecStart lines in the udev
>> Tom
>
> Hi Tom,
> I don't have systemd, I have udev or mdev only.

Sure, but you'll want to do the equivalent on your system as what the
systemd service files describe, which is why I suggest that as a
starting point.

-t