PDC Chassis Log¶
What is PDC Chassis Log¶
The Chassis Log is a feature of some specific type of PDC: PAT PDC equipped with a Guardian Service Processor (GSP), which can be found on recent systems (in particular high-end PA8X00 servers). This feature has two hardware “expression”: the Virtual Front Panel (VFP) and the GSP Logs. The former is the LED panel found on the front bezel of some machines, with Run, Attn, Fault, Power and Remote LEDs; while the latter is about logging special events to the GuardianServiceProcessor logs.
What are we trying to do?¶
The code takes care of reflecting the current state of the system (and its sudden changes) on the VFP and GSP Logs. That is to say for instance that upon system boot, a message is sent to the PDC to notify it of the boot progress; or if the system is taken down by a kernel panic, to reflect that failure on the front panel and log it on the GSP.
How do we do it?¶
Accessing the PDC¶
First, we had to implement the missing abstraction logic in
firmware.c to access the Chassis Log. We had to add the required
interfaces to PDC_CHASSIS_LOG calls:
Function |
Role |
|---|---|
|
This call sends the message expressed by `state` and `data` to the PAT PDC logs |
We are now ready to send data to the Chassis Log.
Anatomy of the Log messages¶
The log messages are sent using two unsigned long numbers: state
and data. state will actually contain an encoded version of the
GSP log message, while data will reflect an encoded Front Panel LED
status.
These two words are encoded using the logic found in pdc_chassis.h,
bearing in mind that they have to be consistent with what the PDC
knows as a valid log message/led status. That is to say that you
cannot invent a message, you have to respect existing ones that will
be understood by the PDC and the GSP. Hence the preformatted
messages section in pdc_chassis.h.