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+# Logging BIOS POST Codes Through Redfish
+
+Author:
+  Terry Duncan
+
+Primary assignee:
+  Zhikui Ren
+
+Other contributors:
+  Jason Bills, Zhikui Ren
+
+Created:
+  December 23, 2019
+
+## Problem Description
+BIOS Power-On Self-Test (POST) codes are exposed on DBUS but not currently over
+Redfish. This describes a method to expose the BIOS POST codes over the Redfish
+interface using the logging service.
+
+## Background and References
+The standard Redfish LogService and LogEntry schemas will be used to expose
+BIOS POST codes. An additional log service (PostCodes) will be added to
+the LogServiceCollection.
+
+Sample [LogService](https://redfish.dmtf.org/schemas/LogService_v1.xml) entry:
+```
+https://obmc/redfish/v1/Systems/system/LogServices/PostCodes
+{
+    "@odata.context": "/redfish/v1/$metadata#LogService.LogService",
+    "@odata.id": "/redfish/v1/Systems/system/LogServices/PostCodes",
+    "@odata.type": "#LogService.v1_1_0.LogService",
+    "Actions": {
+        "#LogService.ClearLog": {
+            "target": "/redfish/v1/Systems/system/LogServices/PostCodes/Actions/LogService.ClearLog"
+        }
+    },
+    "Description": "POST Code Log Service",
+    "Entries": {
+        "@odata.id": "/redfish/v1/Systems/system/LogServices/PostCodes/Entries"
+    },
+    "Id": "BIOS POST Code Log",
+    "Name": "POST Code Log Service",
+    "OverWritePolicy": "WrapsWhenFull"
+}
+```
+
+Events will be exposed using the
+[LogEntry](https://redfish.dmtf.org/schemas/LogEntry_v1.xml) schema.
+```
+https://obmc/redfish/v1/Systems/system/LogServices/PostCodes/Entries
+{
+    "@odata.context": "/redfish/v1/$metadata#LogEntryCollection.LogEntryCollection",
+    "@odata.id": "/redfish/v1/Systems/system/LogServices/PostCodes/Entries",
+    "@odata.type": "#LogEntryCollection.LogEntryCollection",
+    "Description": "Collection of POST Code Log Entries",
+    "Members": [
+        {
+            "@odata.context": "/redfish/v1/$metadata#LogEntry.LogEntry",
+            "@odata.id": "/redfish/v1/Systems/system/LogServices/PostCodes/Entries/B1-03",
+            "@odata.type": "#LogEntry.v1_4_0.LogEntry",
+            "Created": "2019-12-06T14:10:30+00:00",
+            "EntryType": "Event",
+            "Id": "B1-03",
+            "Message": "Boot Count: 4: TS Offset: 0.0033; POST Code: 0x43",
+            "MessageArgs": [
+                4,
+                0.0033,
+                "0x43"
+            ],
+            "MessageId": "OpenBMC.0.1.BiosPostCode",
+            "Name": "POST Code Log Entry",
+            "Severity": "OK"
+        },
+        ...
+    ],
+    "Members@odata.count": 10000,
+    "Name": "BIOS POST Code Log Entries"
+}
+```
+
+A new
+[MessageRegistry](https://redfish.dmtf.org/schemas/MessageRegistry_v1.xml)
+schema entry defines the format for the message.
+```
+https://obmc/redfish/v1/Registries/OpenBMC/OpenBMC
+{
+    "@Redfish.Copyright": "Copyright 2018 OpenBMC. All rights reserved.",
+    "@odata.type": "#MessageRegistry.v1_0_0.MessageRegistry",
+    "Description": "This registry defines the base messages for OpenBMC.",
+    "Id": "OpenBMC.0.1.0",
+    "Language": "en",
+    "Messages": {
+        "BiosPostCode": {
+            "Description": "BIOS Power-On Self-Test Code received.",
+            "Message": "Boot Count: %1: TS Offset: %2; POST Code: %3",
+            "NumberOfArgs": 3,
+            "ParamTypes": [
+                "number",
+                "number",
+                "string"
+            ],
+            "Resolution": "None.",
+            "Severity": "OK"
+        },
+        ...
+    }
+    "Name": "OpenBMC Message Registry",
+    "OwningEntity": "OpenBMC",
+    "RegistryPrefix": "OpenBMC",
+    "RegistryVersion": "0.1.0"
+}
+```
+
+## Requirements
+The Redfish Interface shall be Redfish compliant and pass the Redfish
+compliancy tests.
+
+The Redfish interface shall expose POST codes tracked on DBUS since the last
+BMC reset.
+
+## Proposed Design
+Currently, OpenBMC exposes BIOS POST codes on DBus using the
+xyz.openbmc_project.State.Boot.PostCode service. The existing interface tracks
+POST codes for the past 100 host boot events and the current boot cycle index.
+```
+xyz.openbmc_project.State.Boot.PostCode
+    GetPostCodes(q undefined) → [uint64] undefined
+    CurrentBootCycleIndex = 1
+    MaxBootCycleIndex = 100
+```
+
+The GetPostCodes method is called using the boot cycle index to retrieve the
+codes for the boot cycle.
+```
+{
+  "call": "GetPostCodes",
+  "interface": "xyz.openbmc_project.State.Boot.PostCode",
+  "obj": "/xyz/openbmc_project/State/Boot/PostCode",
+  "result": [
+    1,
+    2,
+    3,
+    4,
+    5,
+    6,
+    17,
+    50,
+    4,
+    173
+  ],
+  "status": "ok"
+}
+```
+
+The existing DBus GetPostCodes method will remain for backward compatibility. A
+new method GetPostCodesTS will be added to include an ISO formatted time stamp
+with micro-second resolution along with each POST code.
+```
+{
+  "call": "GetPostCodesTS",
+  "interface": "xyz.openbmc_project.State.Boot.PostCode",
+  "obj": "/xyz/openbmc_project/State/Boot/PostCode",
+  "result": [
+    {"20191223T143052.632591", 1},
+    {"20191223T143052.634083", 2},
+    {"20191223T143053.928719", 3},
+    {"20191223T143053.930168", 4},
+    {"20191223T143054.512488", 5},
+    {"20191223T143054.513945", 6},
+    {"20191223T143054.960246", 17},
+    {"20191223T143054.961723", 50},
+    {"20191223T143055.368219", 4},
+    {"20191223T143055.369680", 173}
+  ],
+  "status": "ok"
+}
+```
+
+The DBus DeleteAll interface will be implemented to remove entries. The Redfish
+ClearLog action will call the DBus DeleteAll interface.
+```
+{
+  "call": "DeleteAll",
+  "interface": "xyz.openbmc_project.Collection.DeleteAll",
+  "obj": "/xyz/openbmc_project/State/Boot/PostCode",
+  "result": "POST Codes Cleared"
+  "status": "ok"
+}
+```
+
+## Alternatives Considered
+Consideration was given to using the existing DBus method and not exposing
+associated time stamps. In this case, a single log entry could be used per boot
+cycle exposing a string with all POST codes associated with that boot cycle.
+Time stamp data was considered valuable even if the data may be skewed by DBUS.
+
+Consideration was also given to expose the POST codes through a OEM extension
+rather than using the LogEntry schema. Use of OEM extensions to Redfish are
+discouraged. It can be revisited if DMTF adds a schema for POST codes.
+
+## Impacts
+Backward compatibility remains with the existing DBUS interface method.
+Minimal performance impact is expected to track timestamps.
+
+## Testing
+Compliance with Redfish will be tested using the Redfish Service Validator.