Support SAT ATA PASS-THROUGH fixed format sense data

[Christian Franke]

ATA commands like SMART RETURN STATUS (smartctl -H) and SCT ERC GET (smartctl -l scterc) return results in ATA output registers. The SAT ATA PASS-THROUGH commands forward these via sense data.

SAT-1 and older SAT-2 revisions define that the ATA PASS-THROUGH commands always return descriptor format sense data (with ATA Return descriptor) and never return fixed format sense data.

This violates the SPC-4 requirement that the sense data format is controlled by the D_SENSE bit in the Control mode page. Older SCSI layers expecting fixed format may truncate the ATA Return descriptor.

Newer versions of SAT define a fixed (D_SENSE=0) sense data format for the ATA PASS-THROUGH commands. It returns the lower (28-bit command) parts of the ATA output registers and "nonzero" flags for the upper output registers. The SATL may provide the optional ATA PASS-THROUGH Results log page to read the full result.

See ​T10/08-344r2.

scsiata.cpp should be enhanced to detect the new fixed format sense data.

[Alex Samorukov]

Implemented by dpgilbert in r4041.

[Christian Franke]

Related:
​FreeBSD Bug 191717
Ticket #612