Libata error messages

Overview

All libata error messages produced by the kernel use a standard format:

ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
ata3.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0
         res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
ata3.00: status: { DRDY }

Prefix

The prefix

ata3.00:

decodes as

Exception line

The exception line gives an overview of the EH (Error Handler) state.

exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen

Input taskfile

The "cmd" line gives the ATA command (taskfile) sent to the device:

cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0

This lists ATA registers in the following order:

Output taskfile, error summary

The next line contains a current dump of the ATA device's registers, along with an error summary:

res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)

In order:

Error classes

These are the possible values for the internal error mask in each error message mentioned above.

AC_ERR_XXX, ATA Completion Errors were defined in include/linux/libata.h.

ATA status expansion

The final line

status: { DRDY }

expands the ATA status register returned in the output taskfile into its component bits:

ATA error expansion

If any bits in the Error register are set, the Error register contents will be expanded into its component bits, for example:

error: { ICRC ABRT }

SATA SError expansion

If any bits in the SATA SError register are set, the SError register contents will be expanded into its component bits, for example:

SError: { PHYRdyChg CommWake }

These bits are set by the SATA host interface in response to error conditions on the SATA link. Unless a drive hotplug or unplug operation occurred, it is generally not normal to see any of these bits set. If they are, it usually points strongly toward a hardware problem (often a bad SATA cable or a bad or inadequate power supply).