Re: 2.4/2.6 - ATAPI Zip problem in SCSI mode (DEVFS)

[Andrey Borzenkov]

> The problem is that when having Linux booted and placing a Zip disk into
> the drive then mounting doesn't work. It tells me that the device
> doesn't exist. But the drive was found during boot
>
> So far so good on early 2.4 you simply cd into /dev/scsi.../.../ made an
> 'ls' and voila it gave the device a kick and it created the entry for
> the Zip disk you then can mount it (devfs).
>
> For 2.5 this doesn't work anymore and whenever you want to mount a Zip
> disk you need to boot Linux together with a Disk inside the Drive, so
> during boot it detects the Zip drive + the Disk.

yes devfs was castrated in 2.6 and removable media revalidation has been 
removed without providing any suitable replacement.

If you use devfsd and uncomment these lines in devfsd.conf

# If you have removable media and want to force media revalidation when 
looking
# up new or old compatibility names, uncomment the following lines
# SCSI NEWCOMPAT  /dev/sd/* names
LOOKUP          ^(sd/c[0-9]+b[0-9]+t[0-9]+u[0-9]+)p[0-9]+$      EXECUTE 
/bin/dd if=$mntpnt/\1 of=/dev/null count=1
# SCSI OLDCOMPAT  /dev/sd?? names
LOOKUP          ^(sd[a-z]+)[0-9]+$      EXECUTE /bin/dd if=$mntpnt/\1 
of=/dev/null count=1
# IDE NEWCOMPAT   /dev/ide/hd/* names
LOOKUP          ^(ide/hd/c[0-9]+b[0-9]+t[0-9]+u[0-9]+)p[0-9]+$  EXECUTE 
/bin/dd if=$mntpnt/\1 of=/dev/null count=1
# IDE OLDCOMPAT   /dev/hd?? names
LOOKUP          ^(hd[a-z])[0-9]+$       EXECUTE /bin/dd if=$mntpnt/\1 
of=/dev/null count=1

devfsd will attempt media revalidation on access to /dev/sdaN; if you are 
using canonical devfs names you may add something similar to the above, e.g.

LOOKUP (scsi/.*)/part[0-9]+ EXECUTE /bin/dd if=$mntpnt/$1/disc of=/dev/null 
count=1

this should revalidate media on access to partition. But you won't get 
partition list on simple ls as in 2.4. 

-andrey
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