Jeff Garzik wrote:
> Douglas Gilbert wrote:
>> The 16 byte CDB that Tejun is talking about is the
>> ATA PASS THROUGH (16) SCSI command. That is valid to
>
> I'm talking about the changes to the implementation, which appear to
> mistakenly allow 16-byte CDBs through to the ATAPI device, even if it
> only supports 12-byte CDBs.
>
> I am quite aware of the ATA passthru SCSI command. Heck, the spec had
> input from me. I'm talking about something different.
This is what I saw, with the new ATA subsystem in
lk 2.6.19-rc1:
[root@sas ~]# lsscsi -H
[0] sata_nv
[1] sata_nv
[2] sata_nv
[3] sata_nv
[4] pata_amd
[5] pata_amd
[6] mptsas
[7] aic94xx
[root@sas ~]# lsscsi
[1:0:0:0] disk ATA ST380013AS 3.18 /dev/sdb
[4:0:0:0] disk ATA ST380011A 8.01 /dev/sda
[5:0:1:0] cd/dvd HL-DT-ST DVD-ROM GDR8163B 0L23 /dev/scd0
[root@sas ~]# sg_sat_identify --packet /dev/scd0 -vv
open /dev/scd0 with flags=0x802
ATA pass through (16) cdb: 85 08 0e 00 00 00 01 00 00 00 00 00 00 00 a1 00
ATA pass through (16): transport error: Host_status=0x05 [DID_ABORT]
Driver_status=0x00 [DRIVER_OK, SUGGEST_OK]
ATA pass through (16) failed
[root@sas ~]# sg_sat_identify --packet --len=12 /dev/scd0 -vv
open /dev/scd0 with flags=0x802
ATA pass through (12) cdb: a1 08 0e 00 01 00 00 00 00 a1 00 00
ATA pass through: Fixed format, current; Sense key: Illegal Request
Additional sense: Invalid command operation code
The above were attempts to send IDENTIFY PACKET DEVICE
to the PATAPI cd/dvd drive via the ATA PASS THROUGH
(16 and 12) commands respectively. The first one caught
my attention. Why did it fail with a DID_ABORT?
Whatever the reason both responses are wrong. The second
one is wrong because
- the cd/dvd drive does support that opcode (the error
should be either not ready or incompatible format), or
- it didn't do the ATA PASS THROUGH (12) properly
>> The only clash between MMC and SATL SCSI opcodes is
>> with opcode 0xA1: BLANK in MMC and ATA PASS THROUGH (12)
>
> Ok, so the answer is, yes there is a clash, and thus this change will
> remove the ability for working-today setups to use BLANK.
>
> In order to avoid breaking working setups, a method must be found which
> tells the SATL to not filter out the ATA passthru commands.
Or, as a temporary solution, if the device is ATAPI
carrying a SCSI command set with pdt=5 then:
1) opcode 0xa1 goes straight through (i.e. BLANK)
2) opcode 0x85 works as defined by sat-r09.pdf
(implements the ATA PASS THROUGH (16) SCSI command)
>> This is all about being able to send ATA commands to
>> ATAPI devices that are valid for PACKET devices, examples:
>> IDENTIFY PACKET DEVICE
>> SET FEATURES
>> IDENTIFY DEVICE (should abort command + set signature)
>> DEVICE RESET
>> and I assume there are others.
>
> I am quite aware of the purpose of ATA passthru :)
... and I do comparative analysis of SAT layers and
send bug reports.
Doug Gilbert
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