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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] SCSI emulation
- From: Uwe Seimet <Uwe.Seimet@xxxxxxxxx>
- Date: Sun, 16 Sep 2018 08:49:27 +0200
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Hi Thomas,
> > Just for fun I hacked the MODE SENSE code in hdc.c to not report an
> > error for an unknown mode page. The ASV loader now loads several
> > hundred sectors, which I assume is the complete kernel.) The double
> > bus fault in the attached screenshot vanished after enabling MMU
> > emulation and soft floating point support. Now, after displaying the
> > boot messages, there is a warm boot, without any console output that
> > would indicate what went wrong.
>
> Wow, that's more than I expected already. Do you have any information
> about that missing MODE SENSE page? Would it make sense to emulate it
> in Hatari, or is it too specific for that certain drive?
I only know the CDB, which is 0x1a,0x00,0x04,0x00,0x40,0x00, i.e. it's
the rigid disk drive geometry page, description see below (copied from
the SCSI-2 specification).
Because the boot process continued when I simply commented out the return
statement in line 315 of hdc.c the data returned may not even have relevance.
With SCSI drives the actual geometry does not matter anyway as long as the
driver justreads and writes. The only non-exotic fields in this mage page are
the cylinder and heads counts, and if Hatari just returns some meaningful
values here, just like I guess it does for IDE drives, the emulation of this
mode page should be fine.
Best regards
Uwe
---
9.3.3.7 Rigid disk drive geometry page
The rigid disk drive geometry page (see table 171) specifies parameters
for direct-access devices employing a rigid disk drive.
Table 171 - Rigid disk drive geometry page
+=====-========-========-========-========-========-========-========-========+
| Bit| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|Byte | | | | | | | | |
|=====+========+========+=====================================================|
| 0 | PS |Reserved| Page code (04h) |
|-----+-----------------------------------------------------------------------|
| 1 | Page length (16h) |
|-----+-----------------------------------------------------------------------|
| 2 | (MSB) |
|- - -+--- Number of cylinders ---|
| 4 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 5 | Number of heads |
|-----+-----------------------------------------------------------------------|
| 6 | (MSB) |
|- - -+--- Starting cylinder-write precompensation ---|
| 8 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 9 | (MSB) |
|- - -+--- Starting cylinder-reduced write current ---|
| 11 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 12 | (MSB) |
|-----+--- Drive step rate ---|
| 13 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 14 | (MSB) |
|- - -+--- Landing zone cylinder ---|
| 16 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 17 | Reserved | RPL |
|-----+-----------------------------------------------------------------------|
| 18 | Rotational offset |
|-----+-----------------------------------------------------------------------|
| 19 | Reserved |
|-----+-----------------------------------------------------------------------|
| 20 | (MSB) |
|-----+--- Medium rotation rate ---|
| 21 | (LSB) |
|-----+-----------------------------------------------------------------------|
| 22 | Reserved |
|-----+-----------------------------------------------------------------------|
| 23 | Reserved |
+=============================================================================+
The parameters savable (PS) bit is only used with the MODE SENSE
command. This bit is reserved with the MODE SELECT command. A PS bit
of one indicates that the target is capable of saving the page in a
non-volatile vendor-specific location.
NOTE 135 This page is intended to define drive geometry parameters of
rigid disk drives. It may be used for other devices if applicable.
The number of cylinders field defines the number of physical cylinders
used for data storage.
The number of heads field defines the physical number of heads used for
data storage. Heads used exclusively for servo information are
excluded.
The starting cylinder for write precompensation field is the physical
cylinder at which write precompensation is to begin. The first
cylinder is number zero. If the starting cylinder for write
precompensation is equal to the value in the number of cylinders field,
write precompensation shall be disabled by the target.
The starting cylinder for reduced write current field is the physical
cylinder at which write current is reduced. The first cylinder is
number zero. If the starting cylinder for reduced write current is
equal to the value in the number of cylinders field, reduced write
current shall be disabled by the target.
The drive step rate field indicates the step rate in 100 ns increments.
The target shall use the drive step rate, greater than or equal to the
drive step rate specified. If the target rounds this field it shall
terminate the command as described in 7.5.4. A value of zero requests
the target to set its default value.
The landing zone cylinder field indicates two's complement location
where the target shall position the disk heads. A negative value
indicates that the heads are positioned below cylinder zero by that
number of cylinders. A positive value greater than the number of
cylinders indicates that the heads are positioned beyond the cylinders
used for data storage at the cylinder location specified. A zero
indicates that the default should be used.
The rotational position locking (RPL) field is used for spindle
synchronization as defined in table 172. See K of the ANSI X3.170A-
1991 for further information on synchronized spindles.
Table 172 - Rotational position locking
+=======-=====================================================================+
| RPL | Description |
|-------+---------------------------------------------------------------------|
| 00b | Indicates that spindle synchronization is disabled or not supported|
| 01b | The target operates as a synchronized-spindle slave |
| 10b | The target operates as a synchronized-spindle master |
| 11b | The target operates as a synchronized-spindle master control |
+=============================================================================+
NOTE 136 The signals and connectors used for rotational position locking
are external to the SCSI bus and are not part of this International
Standard.
If a target fails to achieve synchronization it shall create a unit
attention condition to all initiators. The sense key shall be set to
UNIT ATTENTION and the additional sense code set to RPL STATUS CHANGE.
If subsequent to achieving synchronization the target detects a change
of synchronization:
a) and, if the logical unit is not presently executing an I/O
process for the initiator, the target shall create a unit
attention condition. The sense key shall be set to UNIT
ATTENTION and the additional sense code set to RPL STATUS CHANGE.
b) and, if the logical unit is presently executing an I/O process
and no other error occurs, then the target shall return CHECK
CONDITION status. The sense key shall be set to RECOVERED ERROR
if the target is able to complete the I/O process or HARDWARE
ERROR if the target is unable to complete the I/O process. The
additional sense code is set to RPL STATUS CHANGE.
The rotational offset indicates the amount of rotational skew that the
target shall use when synchronized. The rotational skew is applied in
the retarded direction (lagging the synchronized spindle master
control). The value in the field is the numerator of a fractional
multiplier that has 256 as its denominator (e.g. a value of 128
indicates a one-half revolution skew). A value of zero indicates that
rotational offset shall not be used. This value may be rounded as
defined in 7.5.4. The rotational offset is not used when a target is
configured as synchronized-spindle master.
The medium rotation rate indicates the speed at which the medium
rotates. The unit of measure is rotations per minute (e.g. 3 600 rpm).