procfs problems -cmdline turncated at 256 bytes ?

[Pete French]

running 4.8 stable, the cmdline file in /proc/$$ seems to be trucated
at, or before 256 bytes for very long command lines. I cant find
any refernec to this behaviour in the manpage, nor does google reveal
anything. I took a look in the source, but didnt properly understand what
was going on - the comments imply that it does give the full commandline
for the current process, however.

any suggestions ? any alternative ways to get hold of the arguments from
within a running program (which doesnt have access to "main()").

-pcf.