Re: no need for a devfs

Richard Gooch (rgooch@atnf.CSIRO.AU)
Wed, 7 Jan 1998 22:38:57 +1100

Pavel Machek writes:
> Hi!
>
> > back to the topic :
> > with the above registry in /proc, and a good makedev software (more a
> > device manager), i see no need for a /dev filesystem.
>
> Well, you would have to rerun makedev software every time module is
> inserted. Advantage of devfs was that it was up-to-date without
> needing to run makedev after every change. devfs also might have
> chance to solve scsi naming problems.

Thank you, Pavel. The running of makedev every time a module is
loaded/unloaded is likely to be *much* slower than devfs.

And I certainly have SCSI disc naming in my sights... With devfs you
can have both the old-style /dev/sd{a,b,c} as well as something like
the Solaris scheme:

/dev/hHcCiIlLpP

where <H> is the host controller number, <C> is the channel number,
<I> is the SCSI ID, <L> is the logical unit and <P> is the partition
number (stripe in Solaris parlance). So, the following system:

scsi : 1 host.
Detected scsi disk sda at scsi0, channel 0, id 0, lun 0
Detected scsi disk sdb at scsi0, channel 0, id 1, lun 0
Detected scsi disk sdc at scsi0, channel 0, id 3, lun 0
Partition check:
sda: sda1 sda2 sda3 sda4 < sda5 sda6 sda7 >
sdb: sdb1
sdc: sdc1 sdc2

would have the following:

/dev/h0c0i0l0p1
/dev/h0c0i0l0p2
/dev/h0c0i0l0p3
/dev/h0c0i0l0p4
/dev/h0c0i0l0p5
/dev/h0c0i0l0p6
/dev/h0c0i0l0p7

/dev/h0c0i1l0p1

/dev/h0c0i3l0p1
/dev/h0c0i3l0p2

Regards,

Richard....