Re: udev and the kernel's idea of a device

[Greg KH <greg@kroah.com>]

On Tue, Apr 06, 2004 at 03:22:29PM -0400, Bill Nottingham wrote:
> udev does not actually change the intrinsic name inside the kernel,
> wherever such a thing might be kept. [*]
> 
> So, say you have a disk error, of some sort. It gets logged in the
> logs, and a few days later you go to figure out what happened.
> 
> It can be logged in various ways:
> 
> - it can print out the 'kernel' device name.
> 
>    From a user perspective who's using udev, this isn't useful -
>    you need a reverse mapping.

Which udev can provide you easily, using udevinfo.

> - it can print out the, say, host-channel-id-lun
> 
>    Again, here you need a reverse mapping.

True, but tools lie sysfsutils provide this mapping.  That's why
dev_printk() and friends were created for.

> - it can print out the major/minor

Ick.  That just doesn't make much sense.

>    Of course, the major/minor are dynamic. So, not only do you need
>    a reverse mapping, you need a mapping that has a timeframe associated
>    with each mapping for when it was valid.
> 
> Am I missing something here? Are there better ways to handle this?

So what would you prefer the kernel to print out?  As it is very simple
to translate from the kernel device name to the real /dev name at any
point in time using udevinfo, why is that not sufficient?

thanks,

greg k-h


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