Re: /dev/fw major not constant (embedded mdev devtmpfs ieee1394)

[Greg KH <greg@kroah.com>]

On Thu, Jan 21, 2010 at 09:56:10PM +0100, Paul Chavent wrote:
> Hi.
> 
> I'am working on an embedded gnu/linux system that allow to capture an ieee1394 stream.
> 
> The system is compound of a kernel, a basic initrd (libc,libgcc,busybox,libdc1394,...) and my app.
> 
> I use the new firewire stack.
> 
> As my system is very minimalist, i tought to create the nodes in /dev at the moment of building my initrd.
> 
> But when i needed to modify my kernel configuration, it has changed the major number of /dev/fw*.
> 
> It's not really important for the definitive system (it will be
> freeze), but i wonder how to solve this issue for my future works ?
> 
> I don't need hotplug, i just need to fill /dev at startup (coldplug).
> The target is an embedded device, so it should be easy to
> build/configure/install, and lightweight.
> 
> For those reasons i don't want to use udev.

Why, is udev somehow not "lightweight"?

> I tried mdev (i run mdev -s in my startup script) from busybox. The
> problem is that mdev only look in /sys/class for filling /dev (i have
> notified their mailing list
> http://lists.busybox.net/pipermail/busybox/2010-January/071384.html).
> 
> The linux ieee1394 wiki people give me some idea (http://marc.info/?t=126390679500003&r=1&w=2) :
>   - maintain a local patch for making the major constant
>   - use devtmpfs
> 
> I prefer to try devtmpfs, but i would like to have your opinion on how
> would you do for me ?

I would recommend using devtmpfs, this is exactly why it was created,
and is how lots of others are using it.  Why not try it out?

thanks,

greg k-h