Advanced Configuration and Power Interface Specification

ACPI Platform Error Interfaces (APEI)
own purposes. It may use these bits to indicate the busy/free status of an error record, to record an
internal identifier, etc.
Table 18-339 Error Record Serialization Info
Field
Bit
Length
Bit
Offset
Description
Signature 16 0 16-bit signature (‘ER’) identifying the start of the error
record serialization data.
Platform Serialization Data 48 16 Platform private error record serialization information.
18.5.2 Operations
The error record serialization interface comprises three operations: Write, Read, and Clear. OSPM
uses the Write operation to write a single error record to the persistent store. The Read operation is
used to retrieve a single error record previously recorded to the persistent store using the write
operation. The Clear operation allows OSPM to notify the platform that a given error record has
been fully processed and is no longer needed, allowing the platform to recover the storage associated
with a cleared error record.
Where the Error Log Address Range is NVRAM, significant optimizations are possible since
transfer from the Error Log Address Range to a separate storage device is unnecessary. The platform
may still, however, copy the record from NVRAM to another device, should it choose to. This
allows, for example, the platform to copy error records to private log files. In order to give the
platform the opportunity to do this, OSPM must use the Write operation to persist error records even
when the Error Log Address Range is NVRAM. The Read and Clear operations, however, are
unnecessary in this case as OSPM is capable of reading and clearing error records without assistance
from the platform.
18.5.2.1 Writing
To write a single HW error record, OSPM executes the following steps:
1. Initializes the error record’s serialization info. OSPM must fill in the Signature.
2. Writes the error record to be persisted into the
3. Error Log Address Range.
4. Executes the BEGIN_WRITE_OPERATION action to notify the platform that a record write
operation is beginning.
5. Executes the SET_RECORD_OFFSET action to inform the platform where in the
6. Error Log Address Range the error record resides.
7. Executes the EXECUTE_OPERATION action to instruct the platform to begin the write
operation.
8. Busy waits by continually executing CHECK_BUSY_STATUS action until FALSE is returned.
9. Executes a GET_COMMAND_STATUS action to determine the status of the write operation.
If an error is indicated, the OS
10. PM may retry the operation.
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