Hi Alan,
I'm using virtually the same startup script as is used in Ubuntu 
(attached).  It only uses $udevadm trigger, with no arguments.  I didn't 
expect that permissions would be an issue, as this system is running in 
single user mode.

Mounting /dev as a tmpfs makes perfect sense to me, however I'll have to 
do some hacking before I can modify that.  I have a list of all the 
devices to be created and placed in /dev already.  Currently, it's 
expanded at compile time, but I should be able to change the target from 
/dev to /lib/udev/devices.

One additional thing that I need to do while migrating away from a 
static /dev is to convert our current naming scheme for devices to one 
which is consistent with the naming that udev uses by default.

Thanks again,
Brendan

Alan Jenkins wrote:
> Hi
>
> On 9/25/09, Brendan Moran <bremoran@broadcom.com> wrote:
>   
>> Hi,
>> I'm trying to migrate an armeb embedded Linux build from a static /dev
>> to udev.  I now have the system coming up with udev enabled, but the
>> first thing that udev does is disable my console connection.  Before the
>> console starts endlessly spewing "file not found" messages,
>>     
>
> Ow.  Often that means you've either deleted or removed access
> permissions to /dev/null.  Maybe the same has happened to /dev/tty or
> something as well.  It suggests that your rules are failing to assign
> permissions to these devices, so udev is giving them default
> permissions which are too restrictive.
>
>   
>> udev prints
>> a line like this
>>
>>     tty ttyAMA0: uevent: unsupported action-string; this will be ignored
>>     in a futur
>>
>> for nearly every device that was in the previous static /dev.
>>     
>
> Aha.  That's a kernel message, not a udev one.  It suggests you're doing this:
>
> udevadm trigger --action=uevent
>
> when you should be doing this:
>
> udevadm trigger --action=add
>
> ("udevadm trigger" should also work since --action=add is the default).
>
>   
>> I understand that I can add static rules to udev to fix this, but I also
>> want to migrate naming conventions to standard names--ttyAMA0 should be
>> ttyS0, etc.  I can keep legacy names around with symlinks if necessary.
>>     
>
> I suspect this is not relevant to your problems.  Udev doesn't delete
> the previous contents of /dev.  There should only be problems if the
> names conflict, so that udev overwrites one of your existing nodes
> with something you're not expecting.
>
> (Btw, in case you're not already doing this, the README recommends you
> mount /dev as a tmpfs and initialize it by copying all your static
> devices from /lib/udev/devices).
>
>   
>> So I'm not quite sure how to get started.  I have disabled udev's
>> startup for the moment, so I can get into /sys.  Is there a guide
>> somewhere on how to migrate from a static /dev to udev?
>>
>> Thanks,
>> Brendan
>>     
>
>