Re: Documentation for sysfs, hotplug, and firmware loading.

Rob Landley
2007-07-21T03:48:31Z

On Friday 20 July 2007 4:09:36 am Greg KH wrote:
> On Fri, Jul 20, 2007 at 09:54:01AM +0200, Cornelia Huck wrote:
> > On Fri, 20 Jul 2007 00:00:01 -0700,
> >
> > Greg KH <greg@kroah.com> wrote:
> > > > I don't insist on it, mknod insists on it. You cannot mknod a dev
> > > > node without specifying block or char.
> > > >
> > > > You're saying that sysfs should provide major and minor numbers
> > > > without anywhere specifying "char" or "block", meaning the major and
> > > > minor numbers cannot be _used_. I am insisting on getting the third
> > > > piece of information without which "major" and "minor" are useless.
> > > >
> > > > I asked very specifically about this at OLS, several times. What
> > > > you're telling me now seems to contradict what you told me then.
> > >
> > > Here's the rule:
> > > If the SUBSYSTEM is "block", it's a block device. Otherwise
> > > it's a char device.
> >
> > That's actually quite confusing to the casual reader, since:
> > > But also realize that the majority of events you will get have nothing
> > > to do with device nodes. I think you are forgetting this fact.
> >
> > So the rule should be:
> > If the SUBSYSTEM is "block" (implying major/minor are provided),
> > it's a block device.
> > If the SUBSYSTEM is not "block", and major/minor are provided,
> > it's a char device.
> > If major/minor are not provided, the event/device is not
> > relevant to device node creation.
>
> Yes, that is much more descriptive, thanks.

agreed, thanks.

I'll try to post an updated version of my hotplug documentation later tonight.
(Just a _touch_ jetlagged at the moment, though. It may only be 9:47
california time, but it's 11:47 on the east cost. I think.)

> greg k-h

Rob
--
"One of my most productive days was throwing away 1000 lines of code."
- Ken Thompson.