Re: [PATCH net-next v2 0/7] mlxsw: Add extended ACK for EMADs

[Jakub Kicinski <jakub.kicinski@netronome.com>]

On Tue, 12 Nov 2019 08:48:23 +0200, Ido Schimmel wrote:
> From: Ido Schimmel <idosch@mellanox.com>
> 
> Shalom says:
> 
> Ethernet Management Datagrams (EMADs) are Ethernet packets sent between
> the driver and device's firmware. They are used to pass various
> configurations to the device, but also to get events (e.g., port up)
> from it. After the Ethernet header, these packets are built in a TLV
> format.
> 
> Up until now, whenever the driver issued an erroneous register access it
> only got an error code indicating a bad parameter was used. This patch
> set adds a new TLV (string TLV) that can be used by the firmware to
> encode a 128 character string describing the error. The new TLV is
> allocated by the driver and set to zeros. In case of error, the driver
> will check the length of the string in the response and report it using
> devlink hwerr tracepoint.
> 
> Example:
> 
> $ perf record -a -q -e devlink:devlink_hwerr &
> 
> $ pkill -2 perf
> 
> $ perf script -F trace:event,trace | grep hwerr
> devlink:devlink_hwerr: bus_name=pci dev_name=0000:03:00.0 driver_name=mlxsw_spectrum err=7 (tid=9913892d00001593,reg_id=8018(rauhtd)) bad parameter (inside er_rauhtd_write_query(), num_rec=32 is over the maximum  number of records supported)
> 
> Patch #1 parses the offsets of the different TLVs in incoming EMADs and
> stores them in the skb's control block. This makes it easier to later
> add new TLVs.
> 
> Patches #2-#3 remove deprecated TLVs and add string TLV definition.
> 
> Patches #4-#7 gradually add support for the new string TLV.
> 
> v2:
> * Use existing devlink hwerr tracepoint to report the error string,
>   instead of printing it to kernel log

Thanks, this is much better! 👍