how to use udev

how to use udev

[Roman Duka]

could somebody explain to me please how to use this udev thing
i've compiled and installed udev-012 and hotplug-2003_08_05
udev documentaion says "Add and remove devices from the system and 
marvel as nodes are creaed and removed in /udev/ based on the device 
types" so how do I add devices? Do I have to call "mknod" or just 
calling "modprobe" to load a give device module would be enough? I mean 
neither seems to work, I get absolutely nothing in /dev/ or /udev/ ??? 
Am I missing something here???

PS proc and sysfs are both mounted on /proc and /sys, I have some 
entries in /proc and /sys but that's about it, nothing in /dev or /udev

Cheers for your help



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Re: how to use udev

[Greg KH]

On Sat, Jan 03, 2004 at 01:38:02AM +0000, Roman Duka wrote:
> could somebody explain to me please how to use this udev thing
> i've compiled and installed udev-012 and hotplug-2003_08_05
> udev documentaion says "Add and remove devices from the system and 
> marvel as nodes are creaed and removed in /udev/ based on the device 
> types" so how do I add devices? Do I have to call "mknod" or just 
> calling "modprobe" to load a give device module would be enough? I mean 
> neither seems to work, I get absolutely nothing in /dev/ or /udev/ ??? 
> Am I missing something here???

If you go into the test directory, after installing udev, and run the
test.all script as root with the 'add' paramater:
	test.all add

Do you see new nodes show up in /udev?

If not, something is not installed properly.

If there are nodes, great, it's working :)

thanks,

greg k-h


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Re: how to use udev

[Roman Duka]

Greg KH wrote:
> On Sat, Jan 03, 2004 at 01:38:02AM +0000, Roman Duka wrote:
> 
>>could somebody explain to me please how to use this udev thing
>>i've compiled and installed udev-012 and hotplug-2003_08_05
>>udev documentaion says "Add and remove devices from the system and 
>>marvel as nodes are creaed and removed in /udev/ based on the device 
>>types" so how do I add devices? Do I have to call "mknod" or just 
>>calling "modprobe" to load a give device module would be enough? I mean 
>>neither seems to work, I get absolutely nothing in /dev/ or /udev/ ??? 
>>Am I missing something here???
> 
> 
> If you go into the test directory, after installing udev, and run the
> test.all script as root with the 'add' paramater:
> 	test.all add
> 
> Do you see new nodes show up in /udev?
> 
> If not, something is not installed properly.
> 
> If there are nodes, great, it's working :)
> 

No Greg I don't get anything in /udev the script calls udev and there 
are no error messages or anything, however /udev is still empty I need 
to ask you a few questions:
- I compiled udev on Linux running kenel 2.4.20, however I am trying to 
get udev working on kernel 2.6.0 which has support for hot-pluggable 
devices and module loading/unloading enabled. I don't think I need to be 
running kernel 2.6.0 in order to just compile udev, am I correct here??
- I didn't switch my system to kernel 2.6.0 and udev, I am trying to 
test it within initrd (Initial Ram Disk), so what I have is a 
subdirectory in my home directory, where I installed busybox, bash, 
insmod, modprobe, hotplug scripts and udev, plus the needed shared 
libraries in /lib. Note I installed udev with the following command 
"make DESTDIR=mydir install" i.e. I didn't use "prefix" so all the 
config files etc should be relative to the root directory, and I've 
checked them, they're fine. I created a initrd and put it on a CD-RW 
disk and that's what I am booting from and testing udev. My question is, 
does running udev withing initrd make any impact on its operations? May 
be the reason why it doesn't work for me is because it has some issues 
in initrd environment???

If nothing else, what else do you think could be wrong??



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Re: how to use udev

[Greg KH]

On Sat, Jan 03, 2004 at 05:54:24AM +0000, Roman Duka wrote:
> 
> No Greg I don't get anything in /udev the script calls udev and there 
> are no error messages or anything, however /udev is still empty I need 
> to ask you a few questions:

Ick.  You ran that as root, right?

Hm, try running the udev-test.pl script in that directory.  Let us know
if the tests there pass or not.  They should.

> - I compiled udev on Linux running kenel 2.4.20, however I am trying to 
> get udev working on kernel 2.6.0 which has support for hot-pluggable 
> devices and module loading/unloading enabled. I don't think I need to be 
> running kernel 2.6.0 in order to just compile udev, am I correct here??

You are correct.  You can build udev on any kernel.  _but_ the test.all
script will _not_ show anything in /udev if you are not on a 2.6.0
kernel.  That's probably the problem.

The udev-test.pl script will work on any kernel, it uses its own fake
sysfs tree.

> - I didn't switch my system to kernel 2.6.0 and udev, I am trying to 
> test it within initrd (Initial Ram Disk), so what I have is a 
> subdirectory in my home directory, where I installed busybox, bash, 
> insmod, modprobe, hotplug scripts and udev, plus the needed shared 
> libraries in /lib. Note I installed udev with the following command 
> "make DESTDIR=mydir install" i.e. I didn't use "prefix" so all the 
> config files etc should be relative to the root directory, and I've 
> checked them, they're fine. I created a initrd and put it on a CD-RW 
> disk and that's what I am booting from and testing udev. My question is, 
> does running udev withing initrd make any impact on its operations?

It shouldn't.  You built the klibc version, right?

> May be the reason why it doesn't work for me is because it has some
> issues in initrd environment???

Is sysfs mounted when udev is called?  That's a requirement.

thanks,

greg k-h


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Re: how to use udev

[Jon Smirl]

udev won't work if sysfs isn't mounted. from fstab...
none                    /sys                    sysfs   defaults        0 0

Does your sysfs directory have a class directory?
under the various classes do they have dev attributes?
For example: /sys/class/tty/console/dev

Without these dev entries udev won't work. They should be automatically
generated by the device drivers.

--- Roman Duka <rduka@mail.ru> wrote:
> > If you go into the test directory, after installing udev, and run the
> > test.all script as root with the 'add' paramater:
> > 	test.all add
> > 
> > Do you see new nodes show up in /udev?
> > 
> > If not, something is not installed properly.
> > 
> > If there are nodes, great, it's working :)
> > 
> 
> No Greg I don't get anything in /udev the script calls udev and there 
> are no error messages or anything, however /udev is still empty I need 
> to ask you a few questions:
> - I compiled udev on Linux running kenel 2.4.20, however I am trying to 
> get udev working on kernel 2.6.0 which has support for hot-pluggable 
> devices and module loading/unloading enabled. I don't think I need to be 
> running kernel 2.6.0 in order to just compile udev, am I correct here??
> - I didn't switch my system to kernel 2.6.0 and udev, I am trying to 
> test it within initrd (Initial Ram Disk), so what I have is a 
> subdirectory in my home directory, where I installed busybox, bash, 
> insmod, modprobe, hotplug scripts and udev, plus the needed shared 
> libraries in /lib. Note I installed udev with the following command 
> "make DESTDIR=mydir install" i.e. I didn't use "prefix" so all the 
> config files etc should be relative to the root directory, and I've 
> checked them, they're fine. I created a initrd and put it on a CD-RW 
> disk and that's what I am booting from and testing udev. My question is, 
> does running udev withing initrd make any impact on its operations? May 
> be the reason why it doesn't work for me is because it has some issues 
> in initrd environment???
> 
> If nothing else, what else do you think could be wrong??
> 
> 
> 
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Re: how to use udev

[Roman Duka]

Greg KH wrote:
>>- I didn't switch my system to kernel 2.6.0 and udev, I am trying to 
>>test it within initrd (Initial Ram Disk), so what I have is a 
>>subdirectory in my home directory, where I installed busybox, bash, 
>>insmod, modprobe, hotplug scripts and udev, plus the needed shared 
>>libraries in /lib. Note I installed udev with the following command 
>>"make DESTDIR=mydir install" i.e. I didn't use "prefix" so all the 
>>config files etc should be relative to the root directory, and I've 
>>checked them, they're fine. I created a initrd and put it on a CD-RW 
>>disk and that's what I am booting from and testing udev. My question is, 
>>does running udev withing initrd make any impact on its operations?
> 
> 
> It shouldn't.  You built the klibc version, right?
> 
no I didn't, udev was linked against glibc, does it have to be linked 
against klibc? I mean I have glibc.so.6 and ld-linux.so.2 in my initrd 
environment
roman@athlon1000:~/kernel/udev-012> ldd udev
         libc.so.6 => /lib/libc.so.6 (0x4001e000)
         /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
roman@athlon1000:~/kernel/udev-012>

> 
>>May be the reason why it doesn't work for me is because it has some
>>issues in initrd environment???
> 
> 
> Is sysfs mounted when udev is called?  That's a requirement.
yeah proc and sysfs are mounted on /proc and /sysfs

-- 
http://www.spetsnazlinux.com
[ Kick-Ass Linux server project ]



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Re: how to use udev

[Roman Duka]

Jon Smirl wrote:
> udev won't work if sysfs isn't mounted. from fstab...
> none                    /sys                    sysfs   defaults        0 0
> 
> Does your sysfs directory have a class directory?
> under the various classes do they have dev attributes?
> For example: /sys/class/tty/console/dev
> 
> Without these dev entries udev won't work. They should be automatically
> generated by the device drivers.
> 
no I mount it by hand
mount -t sysfs none /sys
and there are entries under /sys :-)



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Re: how to use udev

[Roman Duka]

Here is the output of that perl script, any ideas??

roman@athlon1000:~/kernel/udev-012/test> ./udev-test.pl > out 2>&1
roman@athlon1000:~/kernel/udev-012/test> mc

roman@athlon1000:~/kernel/udev-012/test> cat out

udev-test will run 30 tests:

TEST: label test of scsi disc
method 'LABEL' for 'block/sda' expecting node 'boot_disk'
add: error
Can't exec "tree": No such file or directory at ./udev-test.pl line 382.

remove: ok

TEST: label test of scsi partition
method 'LABEL' for 'block/sda/sda1' expecting node 'boot_disk1'
add: error
Can't exec "tree": No such file or directory at ./udev-test.pl line 382.

remove: ok

TEST: label test of pattern match
method 'LABEL' for 'block/sda/sda1' expecting node 'boot_disk1'
add: error
Can't exec "tree": No such file or directory at ./udev-test.pl line 382.

remove: ok


.........etc


rm: cannot change to directory `udev-root/visor': Permission denied
rm: cannot remove directory `udev-root': Directory not empty
roman@athlon1000:~/kernel/udev-012/test>

roman@athlon1000:~/kernel/udev-012/test> ls -l udev-root/
total 1
drw-rw-rw-    2 roman    users          48 Jan  3 06:21 visor
roman@athlon1000:~/kernel/udev-012/test>

Ahh? no execute permissions for directory? Is it supposed to be like that?



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Re: how to use udev

[Jon Smirl]

It doesn't work without execute permissions

[root@smirl init.d]# chmod 666 /udev
[root@smirl init.d]# ls /udev
[root@smirl init.d]# ./udev start
Creating initial udev device nodes:                        [  OK  ]
./udev: line 82:  9288 Bus error               $bin block
[root@smirl init.d]# ./udev stop
Removing udev device nodes:                                [  OK  ]
[root@smirl init.d]# chmod 777 /udev
[root@smirl init.d]# ./udev start
Creating initial udev device nodes:                        [  OK  ]
[root@smirl init.d]#


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Re: how to use udev

[Roman Duka]

Roman Duka wrote:
> Here is the output of that perl script, any ideas??
> 
> roman@athlon1000:~/kernel/udev-012/test> ./udev-test.pl > out 2>&1
> roman@athlon1000:~/kernel/udev-012/test> mc
> 
> roman@athlon1000:~/kernel/udev-012/test> cat out
> 
> udev-test will run 30 tests:
> 
> TEST: label test of scsi disc
> method 'LABEL' for 'block/sda' expecting node 'boot_disk'
> add: error
> Can't exec "tree": No such file or directory at ./udev-test.pl line 382.
> 
> remove: ok
> 
> TEST: label test of scsi partition
> method 'LABEL' for 'block/sda/sda1' expecting node 'boot_disk1'
> add: error
> Can't exec "tree": No such file or directory at ./udev-test.pl line 382.
> 
> remove: ok
> 
> TEST: label test of pattern match
> method 'LABEL' for 'block/sda/sda1' expecting node 'boot_disk1'
> add: error
> Can't exec "tree": No such file or directory at ./udev-test.pl line 382.
> 
> remove: ok
> 
> 
> .........etc
> 
> 
> rm: cannot change to directory `udev-root/visor': Permission denied
> rm: cannot remove directory `udev-root': Directory not empty
> roman@athlon1000:~/kernel/udev-012/test>
> 
> roman@athlon1000:~/kernel/udev-012/test> ls -l udev-root/
> total 1
> drw-rw-rw-    2 roman    users          48 Jan  3 06:21 visor
> roman@athlon1000:~/kernel/udev-012/test>
> 
> Ahh? no execute permissions for directory? Is it supposed to be like that?

No ignor this perl test thing, I needed to be root for that, it runs ok, 
but that's about it, everything else is as it was



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Re: how to use udev

[Roman Duka]

Jon Smirl wrote:
> It doesn't work without execute permissions
> 
> [root@smirl init.d]# chmod 666 /udev
> [root@smirl init.d]# ls /udev
> [root@smirl init.d]# ./udev start
> Creating initial udev device nodes:                        [  OK  ]
> ./udev: line 82:  9288 Bus error               $bin block
> [root@smirl init.d]# ./udev stop
> Removing udev device nodes:                                [  OK  ]
> [root@smirl init.d]# chmod 777 /udev
> [root@smirl init.d]# ./udev start
> Creating initial udev device nodes:                        [  OK  ]
> [root@smirl init.d]#
> 
Well I do have execute permissions on my /dev/ and /udev/ directories 
and I run everything as root, I run udev start, and it runs OK, but it 
doesn't populate /dev/ directory. Like I said, I'm running this within 
initrd (Initial RamDisk) so everything is in RAM, including the root 
filesystem.



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Re: how to use udev

[Greg KH]

On Sat, Jan 03, 2004 at 06:10:09AM +0000, Roman Duka wrote:
> Greg KH wrote:
> >>- I didn't switch my system to kernel 2.6.0 and udev, I am trying to 
> >>test it within initrd (Initial Ram Disk), so what I have is a 
> >>subdirectory in my home directory, where I installed busybox, bash, 
> >>insmod, modprobe, hotplug scripts and udev, plus the needed shared 
> >>libraries in /lib. Note I installed udev with the following command 
> >>"make DESTDIR=mydir install" i.e. I didn't use "prefix" so all the 
> >>config files etc should be relative to the root directory, and I've 
> >>checked them, they're fine. I created a initrd and put it on a CD-RW 
> >>disk and that's what I am booting from and testing udev. My question is, 
> >>does running udev withing initrd make any impact on its operations?
> >
> >
> >It shouldn't.  You built the klibc version, right?
> >
> no I didn't, udev was linked against glibc, does it have to be linked 
> against klibc? I mean I have glibc.so.6 and ld-linux.so.2 in my initrd 
> environment
> roman@athlon1000:~/kernel/udev-012> ldd udev
>         libc.so.6 => /lib/libc.so.6 (0x4001e000)
>         /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)

As long are you are sure udev is able to run properly, no, that's fine.
But why not try using a build against klibc, that would remove any need
for glibc.

thanks,

greg k-h


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Re: how to use udev

[Greg KH]

On Sat, Jan 03, 2004 at 06:26:24AM +0000, Roman Duka wrote:
> Here is the output of that perl script, any ideas??
> 
> roman@athlon1000:~/kernel/udev-012/test> ./udev-test.pl > out 2>&1
> roman@athlon1000:~/kernel/udev-012/test> mc
> 
> roman@athlon1000:~/kernel/udev-012/test> cat out
> 
> udev-test will run 30 tests:
> 
> TEST: label test of scsi disc
> method 'LABEL' for 'block/sda' expecting node 'boot_disk'
> add: error
> Can't exec "tree": No such file or directory at ./udev-test.pl line 382.

Ick, something's really wrong.  Wait, you aren't running the script as
root, are you?  That's needed.

thanks,

greg k-h


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