OEM IPMI EthStats

[Vernon Mauery]

On 30-Aug-2018 02:15 PM, Patrick Venture wrote:
>Out of a desire to export link health information, we implemented an
>OEM IPMI command that lets one grab ethernet statistics from a named
>ethernet device on the BMC.  (The NCSI statistics IPMI commands were a
>bit clunky and didn't do what we needed).
>
>The OEM IPMI commands spec is pretty short on this one:
>
>### Ethernet Statistics Command (0x30) {#ethernet-statistics-command-0x30}

I would say that this command could be useful to the entire OpenBMC 
community, so registering it under the OpenBMC OEM table would be good.

>There is the need to read a specific ethernet-level statistic value
>from the BMC.  This is driven primarily to detect link errors that
>require hardware swaps during manufacturing.
>
>This command will be well structured such that there is a request and
>response which mirror to some extent.
>
>The request will specify the ethernet interface by name, as a
>length-prepended string, and the field they're requesting by
>identifier (an unsigned byte).
>
>If the command is not supported, the IPMI OEM handler will respond
>accordingly, however, if the field is not supported or not recognized,
>the command will return 0xcc (invalid field).
>
>The current ethernet statistics available (all future additions must append):
>
>|Identifier |Human Readable Name
>|-----------|--------------------
>|0          |rx_bytes
>|1          |rx_compressed
>|2          |rx_crc_errors
>|3          |rx_dropped
>|4          |rx_errors
>|5          |rx_fifo_errors
>|6          |rx_frame_errors
>|7          |rx_length_errors
>|8          |rx_missed_errors
>|9          |rx_nohandler
>|10         |rx_over_errors
>|11         |rx_packets
>|12         |tx_aborted_errors
>|13         |tx_bytes
>|14         |tx_carrier_errors
>|15         |tx_compressed
>|16         |tx_dropped
>|17         |tx_errors
>|18         |tx_fifo_errors
>|19         |tx_heartbeat_errors
>|20         |tx_packets
>|21         |tx_window_errors
>
>Request
>
>|Byte(s) |Value |Data
>|--------|------|----
>|0x00    |Statistic ID |The identifier of the desired statistic
>|0x01    |Length       |Where you expect the cable, eth0 or eth1, etc
>|0x02..  |The name     |The string, not null-terminated

Rather than using actual ethernet device names, it might be better to 
use IPMI channel numbers or 0..N-1 for the Nth ethernet device. Other 
than that, the interface looks good to me.

--Vernon

>Response
>
>|Byte(s) |Value  |Data
>|--------|-------|----
>|0x00    |Stat ID|The identifier of the desired statistic
>|0x01....|Uint64 |The value.  Because these are counters we don't
>anticipate negative values, and we don't expect overflow.