RFC: sysctl additional functions/macros

[Bruce Evans]

On Thu, 3 Jan 2008, Alfred Perlstein wrote:

> * Julian Elischer <julian at elischer.org> [080103 18:25] wrote:
>> Alfred Perlstein wrote:
>>> Yes, but EINVAL please.
>>
>> I wondered who would be the first to complain about that..
>>
>> "Gee you Juniper people have no sense of humour" :-)  :-)
>
> I just don't see any point in prefering one non-descriptive error
> message over another, other than to confuse/annoy people.

The correct errno (ERANGE) would be descriptive and wouldn't conflict
with the documented meaning of EINVAL.

Checking bounds is good in theory, but the only time I had a problem
with a bound in sysctl was when it enforced an unnecessarily high lower
bound for an interrupt moderation timeout.  It took an edit to test
all values that the hardware supports.

Bruce