Udev issues in today's coming rawhide

John DeDourek dedourek at unb.ca
Thu Mar 2 14:24:45 UTC 2006



Harald Hoyer wrote:
> Olivier Galibert wrote:
> 
>> On Wed, Mar 01, 2006 at 11:55:02PM -0800, Jesse Keating wrote:
>>
>>> We're attempting to fix a problem in udev where /dev/cdrom creation is a
>>> race between multiple optical devices in a system.  To work around this
>>> we will enumerate the devices as /dev/cdrom-hdc or /dev/cdrom-hdb.
>>> However for compatibility reasons, we'll still create a /dev/cdrom, and
>>> the last device found wins the race.
>>
>>
>>
>> And no /dev/cdrom1, etc.  Compatibility is for the weak, I presume?
> 
> 
> enumeration is not possible anymore... we should now have 
> /dev/cdrom-{devname}
> 
Hmmm.  To quote "Greg Kroah-Hartman", from the paper "udev -- A
Userspace Imlementation of devfs", Proceeedings of the Linux Symosium,
July 23th-26th, 2003, Ottawa, Ontario, Canada:
"This paper will discuss udev, a program ... allows for features
that were previously not able to be done through devfs alone, such
as:  Persistent naming for devices when they move around the
device tree."

I guess we can't have persistent naming when they don't move
around the tree (but we reboot).  :0(

Or perhaps this is just a configuration issue and we can have
persistent names (whether they be /dev/cdrom-a and /dev/cdrom-b,
or the more traditional /dev/cdrom1 and /dev/cdrom2, or whatever.
We just can't use "enumeration" to do it.

I will continue working through the available documentation
until I do understand how this stuff works.  But I am finding
it very difficult to understand from the documentation that
I have read to date.

I would appreciate any poitners to additional things that I
should read about sysfs, udev, hotbplug, and drivers.




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