Help: open file limit (Sun-4)

[Guy Harris]

>>1. How do I increase the per-process open file limit (beyond 30)?

>Without source?  Ask Sun.

And they'll say, with good reason, "the only way to do that is to
upgrade to 4.0".  See below. 

>Of course, the mmap system call was fiction so the comment is slightly
>misleading.

It's non-fiction in SunOS; even before 4.0, it was used for mapping
things such as frame buffers into processes' address spaces.  You
*might*, with source, be able to whack on SunOS pre-4.0 to allow more
file descriptors, but to disallow "mmap"ping them; I don't guarantee
that this would prevent the system from getting confused.  You may,
however, have to recompile programs such as "ps" that know the U area is
laid out.

>In 4.3 the comment was removed, the fpte structure was
>changed, NOFILE was bumped up to 64, and mmap was ignored.

In SunOS 4.0 the comment was removed, the 4.3BSD virtual memory system
was almost completely removed and replaced with a brand new one (the
pageout/swapping policy code is still largely 4.3BSD, but little if
anything else is), NOFILE was bumped up to 64, and "mmap" was made to
work on regular files.