Libata error messages

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Contents

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

ata prefix, indicating this is a libata port or device message
3 port number, counting from one (1)
00 device number, usually zero unless Port Multiplier or PATA master/slave is involved

Exception line

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

exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
Emask Error classification bitmask (AC_ERR_xxx in source code)
SAct SATA SActive register
SErr SATA SError register
action ATA_EH_xxx actions, like revalidate, softreset, hardreset (see source code)
frozen if present, indicates the port was frozen for EH
t<number> number of retries

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:

Command
(separator)
Feature
NSect
LBA L
LBA M
LBA H
(separator)
HOB Feature
HOB NSect
HOB LBA L
HOB LBA M
HOB LBA H
tag NCQ tag number, or listed as zero if NCQ is not active/applicable.

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:

Status
(separator)
Error
NSect
LBA L
LBA M
LBA H
(separator)
HOB Error
HOB NSect
HOB LBA L
HOB LBA M
HOB LBA H
Emask ATA command's internal error mask (AC_ERR_xxx in source code)
(summary) An English summary of the error, such as
  • timeout
  • HSM violation
  • media error

ATA status expansion

The final line

status: { DRDY }

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

Busy Device busy (all other bits invalid)
DRDY Device ready. Normally 1, when all is OK.
DRQ Data ready to be sent/received via PIO
DF Device fault
ERR Error (see Error register for more info)
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