udev question

udev question

[Mr Dash Four]

A simple question: in /etc/udev/rules.d/ (on the root partition!) I have 
a .rules file for one of my smartcard devices which has, among other 
things, this statement:

PROGRAM="/bin/sleep 0.1"

This program is not on the initramfs image, but it is in the /bin 
directory on the root partition. I was under the impression that root is 
not mounted until udev has finished its job - is that not the case? If 
so, how is this program executed then? I also have a lot of other 
statements with RUN+=... which also refer to executables not present in 
initramfs - they are all present in the root partition. When/How do 
these execute then?

Am I missing something fundamental here?

Re: udev question

[Harald Hoyer]

On 10/25/2010 07:46 PM, Mr Dash Four wrote:
> A simple question: in /etc/udev/rules.d/ (on the root partition!) I have a
> .rules file for one of my smartcard devices which has, among other things, this
> statement:
>
> PROGRAM="/bin/sleep 0.1"
>
> This program is not on the initramfs image, but it is in the /bin directory on
> the root partition. I was under the impression that root is not mounted until
> udev has finished its job - is that not the case? If so, how is this program
> executed then? I also have a lot of other statements with RUN+=... which also
> refer to executables not present in initramfs - they are all present in the root
> partition. When/How do these execute then?
>
> Am I missing something fundamental here?

udev runs a second time in the real root, just because of this limitation of the 
initramfs.

Re: udev question

[Mr Dash Four]

>>
>> Am I missing something fundamental here?
>
> udev runs a second time in the real root, just because of this 
> limitation of the initramfs.
Yeah, I sort of figured it out yesterday after running a 'probe' version 
of the '90crypt; module. I have another udev-related query though - if 
multiple rules register for the same udev triggers (like 
ENV{ID_FS_TYPE}=='crypto_LUKS') how are they executed and can the order 
of execution be controlled?

The reason I am asking this is because, as it turns out, I may need to 
design a separate module for smartcard tokens to be used with LUKS and 
the way I see this is when LUKS partition gets matched by udev the 
smartcard module needs to get the first go (for all smartcard-specified 
LUKS partitions) then 90crypt (with key file login, possibly falling 
back on password authentication if the key file data is not successful - 
though this, as far as I can see, is not yet implemented!).

Unfortunately, my udev knowledge is not that much to know is that 
possible, hence the my query.

Re: udev question

[Harald Hoyer]

On 10/26/2010 01:20 PM, Mr Dash Four wrote:
>
>>>
>>> Am I missing something fundamental here?
>>
>> udev runs a second time in the real root, just because of this limitation of
>> the initramfs.
> Yeah, I sort of figured it out yesterday after running a 'probe' version of the
> '90crypt; module. I have another udev-related query though - if multiple rules
> register for the same udev triggers (like ENV{ID_FS_TYPE}=='crypto_LUKS') how
> are they executed and can the order of execution be controlled?
>
> The reason I am asking this is because, as it turns out, I may need to design a
> separate module for smartcard tokens to be used with LUKS and the way I see this
> is when LUKS partition gets matched by udev the smartcard module needs to get
> the first go (for all smartcard-specified LUKS partitions) then 90crypt (with
> key file login, possibly falling back on password authentication if the key file
> data is not successful - though this, as far as I can see, is not yet
> implemented!).
>
> Unfortunately, my udev knowledge is not that much to know is that possible,
> hence the my query.

place it in a udev rules file with a lower number... first come, first serve.

Re: udev question

[Mr Dash Four]

>> Unfortunately, my udev knowledge is not that much to know is that 
>> possible,
>> hence the my query.
>
> place it in a udev rules file with a lower number... first come, first 
> serve.
In other words if I do udev/rules.d/65token.rules that should be enough, 
right? I also presume that once the /tmp/crypt-root-asked-$2 is set 
90crypt won't touch it. Is that right?

Udev question

[Vallimar]

Hello!

Mailing you folks is pretty much my last resort, but since I cannot seem
to find the information I'm looking for anywhere, I thought I'd give it a
shot. Essentially, I'm wondering if you might be able to give me a list of
kernel paramaters necessary to make udev work. I run a fairly customized
kernel install and I don't want to enable gobs of options that I don't
need/use. From what I can gather, most places and the documentation itself
indicates you need proc/tmpfs/pty/sysfs, some older ones say you need
hotplug, but from looking at the newer udev, that doesn't seem to be the
case anymore? However, from looking at more info and peeking at the code
a bit and just from the debug errors I get, it seems it requires some
uevent/netlink stuff. The only problem I have with that is with the latest
kernel, there are several netlink options so how am I supposed to know
which ones I need? Right now I have none of them enabled since I've never
needed them but I am trying to get a working parallel udev setup to see if
it would be beneficial for me to switch over to that from a static /dev
tree. In essence, I'm suggesting that it would be nice for us non-distro
users if the udev package contained a list of must-be-enabled kernel options
in order for things to work.


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Re: Udev question

[Kay Sievers]

On Wed, 2006-07-05 at 13:08 -0400, Vallimar wrote:
> Mailing you folks is pretty much my last resort, but since I cannot seem
> to find the information I'm looking for anywhere, I thought I'd give it a
> shot. Essentially, I'm wondering if you might be able to give me a list of
> kernel paramaters necessary to make udev work. I run a fairly customized
> kernel install and I don't want to enable gobs of options that I don't
> need/use. From what I can gather, most places and the documentation itself
> indicates you need proc/tmpfs/pty/sysfs, some older ones say you need
> hotplug, but from looking at the newer udev, that doesn't seem to be the
> case anymore? However, from looking at more info and peeking at the code
> a bit and just from the debug errors I get, it seems it requires some
> uevent/netlink stuff. The only problem I have with that is with the latest
> kernel, there are several netlink options so how am I supposed to know
> which ones I need? Right now I have none of them enabled since I've never
> needed them but I am trying to get a working parallel udev setup to see if
> it would be beneficial for me to switch over to that from a static /dev
> tree. In essence, I'm suggesting that it would be nice for us non-distro
> users if the udev package contained a list of must-be-enabled kernel options
> in order for things to work.

There are no options you can reach, if you don't enable CONFIG_EMBEDDED.
The network stack itself depends on netlink, so you usually can't switch
that off too.

Kay


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Re: Udev question

[Vallimar]

On Wed, July 5, 2006 1:21 pm, Kay Sievers wrote:
>
> There are no options you can reach, if you don't enable CONFIG_EMBEDDED.
> The network stack itself depends on netlink, so you usually can't switch
> that off too.
>

Well, I have networking just fine.. maybe you can suggest why I keep
getting these errors then?

Jul  5 19:08:41 omicron udevd[18429]: main: will daemonize
Jul  5 19:08:41 omicron udevd[18429]: init_uevent_netlink_sock: bind
failed: No such file or directory
Jul  5 19:08:41 omicron udevd[18429]: main: uevent socket not available
Jul  5 19:08:41 omicron udevsettle[18431]: main: queue is empty

And then the daemon terminates...

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Re: Udev question

[Kay Sievers]

On Wed, 2006-07-05 at 19:14 -0400, Vallimar wrote:
> On Wed, July 5, 2006 1:21 pm, Kay Sievers wrote:
> >
> > There are no options you can reach, if you don't enable CONFIG_EMBEDDED.
> > The network stack itself depends on netlink, so you usually can't switch
> > that off too.
> >
> 
> Well, I have networking just fine.. maybe you can suggest why I keep
> getting these errors then?
> 
> Jul  5 19:08:41 omicron udevd[18429]: main: will daemonize
> Jul  5 19:08:41 omicron udevd[18429]: init_uevent_netlink_sock: bind
> failed: No such file or directory
> Jul  5 19:08:41 omicron udevd[18429]: main: uevent socket not available
> Jul  5 19:08:41 omicron udevsettle[18431]: main: queue is empty
> 
> And then the daemon terminates...

Ick, no idea how this can happen.

What does:
  cat /proc/net/netlink
print? It has a line like this, when the daemon is listening:
  sk       Eth Pid    Groups   Rmem     Wmem     Dump     Locks
  f257a800 15  16733  ffffffff 0        0        00000000 2


What does:
  strace -s1000 -t udevmonitor
print? It looks like this, if it works:
  socket(PF_NETLINK, SOCK_DGRAM, 15)      = 4
  bind(4, {sa_family¯_NETLINK, pid\x16739, groupsÿffffff}, 12) = 0

Kay


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udev question

[Lukas Hejtmanek]

Hello,

is is possible to prevent _some_ modules to be loaded at boot time while
allowing them to be loaded later?

I know about /etc/modprobe.d/blacklist but listing a module there prevent
aliases expansion.

E.g. I want ipw2200 module not to be loaded at system boot, but I want this
module to be loaded if I do ifconfig eth1 up. Is this possible?

-- 
Luká¹ Hejtmánek

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