Please support receiving extended console logs from linux kernel

[bdrung]

The Linux kernel supports a extended netconsole log format. https://www.kernel.org/doc/Documentation/networking/netconsole.txt says:

Extended console:
=================

If '+' is prefixed to the configuration line or "extended" config file
is set to 1, extended console support is enabled. An example boot
param follows.

 linux netconsole=+4444@10.0.0.1/eth1,9353@10.0.0.2/12:34:56:78:9a:bc

Log messages are transmitted with extended metadata header in the
following format which is the same as /dev/kmsg.

 <level>,<sequnum>,<timestamp>,<contflag>;<message text>

Non printable characters in <message text> are escaped using "\xff"
notation. If the message contains optional dictionary, verbatim
newline is used as the delimeter.

If a message doesn't fit in certain number of bytes (currently 1000),
the message is split into multiple fragments by netconsole. These
fragments are transmitted with "ncfrag" header field added.

 ncfrag=<byte-offset>/<total-bytes>

For example, assuming a lot smaller chunk size, a message "the first
chunk, the 2nd chunk." may be split as follows.

 6,416,1758426,-,ncfrag=0/31;the first chunk,
 6,416,1758426,-,ncfrag=16/31; the 2nd chunk.

Please add support for receiving extended console logs from linux kernel and combine fragmented logs again.

Currently we use the imudp input module to receive the normal console logs, but this might fragment one log line into multiple log entries.

[bdrung]

https://github.com/facebook/fbkutils contains a library for processing extended netconsole messages from the Linux kernel that is called ncrx.