Date: Thu, 17 Apr 1997 19:18:58 -0500 (CDT) From: Jim Bryant <jbryant@argus> To: bde@zeta.org.au (Bruce Evans) Cc: freebsd-hackers@freebsd.org Subject: Re: optical drives Message-ID: <199704180019.TAA16768@argus> In-Reply-To: <199704171722.DAA06579@godzilla.zeta.org.au> from "Bruce Evans" at Apr 18, 97 03:22:08 am
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In reply:
> [This should be discussed in a technical mailing list, not -hackers.]
>
> >od_open() calls dsopen() calls dsinit() which calls check_part().
> >
> >eventhough dsinit() has a label with the correct geometery, it is
> >looking to verify the geometry by checking the DOS partitions,
> >but optial drives don't have partitions (?) and we get 0 for the value
> >of the sector per cylinder. check_part() does not check to see if the
> >secpercyl is zero before doing an integer divide. This zero value
> >for secpercyl causes the panic.
>
> You are probably supposed to write a partition table. Otherwise, garbage
> may be interpreted as a good partition table with wrong offsets and
> and data at wrong offsets may be written to. A panic is better. It
> takes special garbage to produce the divide by zero error:
>
> - there must be a boot signature 0x55, 0xaa at the end of the MBR
> - all of the bits in the places that are interpreted as ending sector
> numbers must be 0 (this gives max_nsectors == 0 and secpercyl == 0)
> - some of the bits in the places that are interpreted as starting
> sector, head or cylinder numbers must be nonzero (otherwise,
> check_part() is not called). This is unusual when the previous 2
> conditions are met, so the panic is unusual.
>
> Fix: treat the max_nsectors == 0 case as an error.
>
> >The optical drive did not work with the DOS fdisk. I do not know if this
> >means optical media act like diskettes and do not have DOS partitions or
> >fdisk is brain dead.
>
> A partition is just data. Even vn disks can have partitions in FreeBSD.
under dog, use the adaptec afdisk utility [assuming you have adaptec]...
> >Jim Bryant <jbryant@argus> showed that his optical acts like a drive:
> >
> >> (ahc0:1:0): "IBM MTA-3230TC2210!B 0" type 0 removable SCSI 2
> >> sd1(ahc0:1:0): Direct-Access 217MB (446325 512 byte sectors)
> >> sd1(ahc0:1:0): with 17934 cyls, 1 heads, and an average 24 sectors/track
>
> A very tall drive :-).
well, it jives with the IBM MTA3230 manual [which is harder to find than
chicken lips]...
the easiest way to get a magneto-optical working is to simply jumper
it as a type 0 removable... the geometry above is what worked after
many experiments... this just uses the straight scsi driver... no
od0 is required... this is how i prep the disks 230M and 128M [128M
disktab entry follows at end]:
------------------------------------------------------------------------
-rwx------ 1 root wheel 335 Jun 6 1996 mkmo230
------------------------------------------------------------------------
#!/bin/tcsh
echo ""
echo -n $0": writing partition table..."
fdisk -i /dev/rsd1c <<EOF >& /dev/null
y
17934
64
32
y
y
165
32
444384
y
0
1
1
216
63
32
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
y
y
EOF
echo "done."
sleep 2
echo -n $0": writing disk label..."
disklabel -rw /dev/sd1s1 mo230 >& /dev/null
echo "done."
sleep 2
echo -n $0": laying filesystem..."
newfs /dev/sd1s1a >& /dev/null
echo "done."
echo ""
------------------------------------------------------------------------
-rwx------ 1 root wheel 335 Sep 21 1996 mkmo128
------------------------------------------------------------------------
#!/bin/tcsh
echo ""
echo -n $0": writing partition table..."
fdisk -i /dev/rsd1c <<EOF >& /dev/null
y
9994
64
32
y
y
165
32
247776
y
0
1
1
216
63
32
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
0
0
y
0
0
0
0
0
0
y
y
0
y
y
EOF
echo "done."
sleep 2
echo -n $0": writing disk label..."
disklabel -rw /dev/sd1s1 mo128 >& /dev/null
echo "done."
sleep 2
echo -n $0": laying filesystem..."
newfs /dev/sd1s1a >& /dev/null
echo "done."
echo ""
------------------------------------------------------------------------
-rw-r--r-- 1 root wheel 5613 Sep 21 1996 disktab
------------------------------------------------------------------------
mo230|IBM MTA-3230 with 230 Meg 3.5inch Magneto-Optical:\
:ty=removeable:dt=SCSI:rm#3600:\
:se#512:nt#64:ns#32:nc#216:sc#2048:su#444384:\
:pa#444384:oa#0:ba#4096:fa#0:ta=4.2BSD:\
:pc#444384:oc#0:
mo128|IBM MTA-3230 with 128 Meg 3.5inch Magneto-Optical:\
:ty=removeable:dt=SCSI:rm#3600:\
:se#512:nt#64:ns#32:nc#121:sc#2048:su#247776:\
:pa#247776:oa#0:ba#4096:fa#0:ta=4.2BSD:\
:pc#247776:oc#0:
assuming you have a 230M/128M magneto-optical, this [minor tweaking
may be required if you are not using an IBM MTA3230, such as a
Fujitsu] should get you running..
jim
--
All opinions expressed are mine, if you | "I will not be pushed, stamped,
think otherwise, then go jump into turbid | briefed, debriefed, indexed, or
radioactive waters and yell WAHOO !!! | numbered!" - #1, "The Prisoner"
jbryant@tfs.net - KC5VDJ 2M, 70cm, KPC-3+ - kc5vdj@wv0t.#neks.ks.usa.noam
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