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- To: hatari-devel@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [hatari-devel] SCSI emulation
- From: Andreas Grabher <andreas_g86@xxxxxxxxxx>
- Date: Sun, 16 Sep 2018 09:50:35 +0200
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Hello all,
maybe it is worth having a look at Previous' scsi.c:
https://sourceforge.net/p/previous/code/HEAD/tree/trunk/src/scsi.c
There are some mode pages emulated, including rigid disk geometry page. It is obviously good enough to make NeXTstep happy. Feel free to copy this. I wrote it on my own using documentation of some old seagate drive.
Best wishes,
Andreas
Am 16.09.2018 um 08:49 schrieb Uwe Seimet <Uwe.Seimet@xxxxxxxxx>:
> 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).
>
>
>