acpi_ibm(4): new radio kill switch (readonly) sysctl

[Nate Lawson]

Rong-en Fan wrote:
> As pointed out by Henrik Brix Andersen, I adds a sysctl entry
> that shows the status of radio kill switch found on some ThinkPad:
> 
> http://people.freebsd.org/~rafan/acpi_ibm_killswitch.diff
> 
> dev.acpi_ibm.0.killswitch = 0 means the switch is off. It seems that
> no acpi event will be generated when the value changes (actually,
> my x60 does not generate any events when I presses FN+something).
> Otherwise, we can hook it in devd.conf and remove wireless driver when
> kill switch is on...
> 
> Any comments?

Seems fine to me.  But as to the name of the sysctl -- it should be more
logical.  How about renaming it to dev.acpi_ibm.0.radio_enable and when
1, the radio is enabled?  Even if you have to invert the logic of the
ACPI method, it would make more sense to users.  They don't need to know
what's going on under the hood.

-- 
Nate