This is the second article in a series describing the changes in the PI 1.3 specification. This article focuses on the updates to the PI status codes. Actually, quite a minor change, these add status codes for the firmware if it implements support for the ATA specification's Self-Monitoring, Analysis and Reporting Technology (SMART) feature set for hard drives. This feature set allows software to query the hard drives and ask about the types of faults experienced with a view of predicting eventual hard drive failure.
These status codes provide a standardized way for the system firmware to report when SMART is being enabled (EFI_IOB_ATA_BUS_SMART_ENABLE) or disabled (EFI_IOB_ATA_BUS_SMART_DISABLE) or whether it is not supported by the drive (EFI_IOB_ATA_BUS_SMART_NOTSUPPORTED). It also allows the firmware to report if it detects on the many classes of alert conditions, using EFI_IOB_ATA_BUS_SMART_UNDERTHRESHOLD and EFI_IOB_ATA_BUS_SMART_OVERTHRESHOLD.
One of the interesting things is why these were not in the PI Specification in the first place, even though they were in the EDK implementation that Intel developed around the same time. After the EFI 1.10 specification was released, there was a relatively long hiatus with no additional specification versions being released with new material, except for minor errata. People (meaning Intel, Microsoft and a few other companies) were fairly satisfied with EFI 1.10 but who was going to do all the dirty work to implement it. So Intel wrote down the Platform Innovation Framework (or PIF) specification and created a corresponding implementation, called Tiano, showing what they considered best practice for creating EFI implementations. From some comments, Intel intended that much of this work would end up in the future EFI (not UEFI) 2.0 specification.
But then UEFI came, forged by the original nine promoter companies, including Insyde. Intel suspended work on the PIF specifications. But work continued internally. When it came time for the PI specification to be created, using the PIF specifications as a starting point, we tried to gather up any loose ends from Intel's on-going development, but we failed to get these status codes. And thus, SMART status codes were all there; everyone knew about them; but they weren't the standard.
And now they are. So PI 1.3 finally catches up with PIF (at least in this area).