bumping ARG_MAX

[David Holland <dholland-tech%netbsd.org@localhost>]

pkgsrc has grown to the point where the following happens:

   valkyrie% pwd
   /usr/pkgsrc
   valkyrie% grep foo */*/Makefile
   /usr/bin/grep: Argument list too long.
   Exit 1
   valkyrie% 

I've said on a number of occasions over the last few years that this
is the point at which we should consider raising ARG_MAX.

It's currently 256K; changing it to 512K would last a good while, at
least by this criterion.

As far as I know there is no compat logic required, as the only
consumer of ARG_MAX-size data is the kernel, and old versions of e.g.
xargs that use a smaller value won't break.

The downside is that it increases the memory load, and possibly
increases the chances that there'll be trouble allocating the space at
exec time. (I don't actually know how this is done in NetBSD, but
there's only a finite number of reasonably sane ways to go about it
and none of them are immune to load and/or fragmentation.)

thoughts?

-- 
David A. Holland
dholland%netbsd.org@localhost