Date: Thu, 25 Jul 2002 17:04:18 -0700 From: Darren Pilgrim <dmp@pantherdragon.org> To: Marco Berizzi <pupilla@hotmail.com> Cc: hiten@uk.FreeBSD.org, freebsd-newbies@FreeBSD.ORG Subject: Re: block device vs char device Message-ID: <3D409202.B9355D0F@pantherdragon.org> References: <LAW2-F81DQiPsdTV2yC0001da66@hotmail.com>
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Marco Berizzi wrote:
>
> thanks for the patience.
> I have read the man pages you have pointed me
> before writing to the list but they don't
> explain clearly the difference (at least for me).
> Idem the handbook. Sometimes it reports you should
> use cd0c (possibly) and some examples (take a look
> at the SAP installation section) reports cd0a.
>
> Currently for me it is not clear why should I use
> cd0c and not cd0a to mount a cdrom (or viceversa).
> Both device are working well for me (this make me angry!!!).
> I would like to know which is the difference between the
> two nodes (the minors are different).
cd0a and cd0c are different representations of the disc. Reading up on
disklabel will give you some clues about this. The "a" and "c" are
partition numbers, though "c" has special meaning. cd0a refers to the
first ISO filesystem on the CD. cd0c refers to the entire disc. You
should use cd0a for mounting a disc.
There are also the audio-track device nodes: cd0t{1-100). These aren't
created by default (MAKEDEV all). You can create them seperately by
saying, `MAKEDEV cd0t`.
> >From: Hiten Pandya <hitmaster2k@yahoo.com>
> >--- Marco Berizzi <pupilla@hotmail.com> wrote:
> > > Hi Hiten,
> > >
> > > Thanks for the reply about char & block devices.
> > > Now all is much more clean.
> >
> >No Problem.
> >
> > > [ ... ]
> > >
> > > I haven't found anything about the difference
> > > between cd0a & cd0c.
> > > Any hints?
> >
> >OK. Ah my friend, it seems you didnt check the man pages (a very nice
> >discovery :-). For information on 'cd' type devices, look at:
> >
> > 1) http://www.freebsd.org/cgi/man.cgi?query=cd&apropos=0&sektion=4
> > -- This man page contains information about SCSI CDROM Devices.
> >
> > 2) http://www.freebsd.org/cgi/man.cgi?query=ata&apropos=0&sektion=4
> > -- This man page contains information about ATAPI CDROM Devices.
> >
> >Hope this helps.
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