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SubjectRe: My $0.02 on devd and devfs
Date
From
orc@pell.portland.or.us (david parsons)
> In article <linux.kernel.380254A4.F0C32162@pobox.com>,
> Jeff Garzik <jgarzik@pobox.com> wrote:
> >Khimenko Victor wrote:

> >> See above. Try to turn on printer, do `cat something > /dev/printer/0`
> >> with devfs and explain how it'll be handled with devd.

> >Are you implying here that /dev/printer/0 is created at open() time?
> >IMHO that is a bad idea.

> I think that if /dev/printer/0 is controlled by a lkm'ed driver,
> that's exactly what happens, no matter what. I'd expect that in
> the devd case, you'd have to populate /dev with every possible
> device so that you could actually do the open, have the kernel tell
> kmod to load the driver, then the information would go off to devd
> to, ummm....

Nope. devd is notified when the device shows up. It can then go and create
/dev/printer/0 and do some other magic, if needed. When you try to open the
file, it is there. That in turn might trigger loading modules and
initializing the device.

Note that if devd is missing, but the device files are extant, everything
is peachy.
--
Horst von Brand vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Viña del Mar, Chile +56 32 672616

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