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SubjectRe: Devfs, was Re: Migrating to larger numbers
cat@zip.com.au writes:
> On Wed, Jun 09, 1999 at 02:22:16PM +1000, Richard Gooch wrote:
> > Jamie Lokier writes:
> > > Richard Gooch wrote:
> > > > if all your CD-ROMs devices are unloaded and you have module
> > > > autoloading, then to find all CD-ROMs on the system, you just do:
> > > > opendir ("/dev/ide/cd");
> > > > loop;
> > > > opendir ("/dev/sr");
> > > > loop;
> > > >
> > > > and your directory scanning code knows that each and every entry
> > > > (besides "." and "..":-) is a Genuine CD-ROM[tm] that actually exists
> > > > on your system.
> > >
> > > Ugh, it will miss the _other_ CD-ROMs in your system.
> > >
> > > /dev/parport/cd
> > > /dev/pcmcia/cd
> > > /dev/usb/cd
> > >
> > > Doesn't look like the right way to me.
> >
> > It is the right way. The concept is still valid. Just extend my
> > example code. It wasn't meant to be complete, just enough to convey
> > the idea. Did I really have to spell that out?
> >
> > Also, I expect that a PCMCIA CD-ROM will really be an IDE CD-ROM. A
> > parport CD-ROM will probably be either IDE or SCSI.
>
> Out of curiosity, why not also have the reverse? since it's a virtual
> device it can be done automatically and then if you want a cd you can
> open /dev/cd/ (or something similar) and go through anything in there.
> That way you don't have to guess at the possible ways of connecting a
> cd to the machine when you want to find them all.

You can't directly because they come from different drivers. This
scheme works because each of the CD-ROM drivers has it's own
directory. To do what you want would require something clever with
devfsd.

Regards,

Richard....

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