RFC: system-wide default tunables

[DJ Delorie]

Siddhesh Poyarekar <siddhesh@gotplt.org> writes:
> Only stricter overrides to systemwide tunables should be allowed,

This leads to the next question: how to express these constraints in the
tunables.conf file.  A the simplest, prefixing each tunable with '+',
'-', or '=' for example?  For stricter, looser, or can't change?  Else
we need to come up with some more flexible "flag parser".