[PATCH 1/2] hostapd: Add Power Constraint element

Jouni Malinen j at w1.fi
Fri Feb 14 12:25:09 EST 2014

On Fri, Feb 07, 2014 at 10:19:13PM +0100, Marek Puzyniak wrote:
> From: Srinivasan B <srinivasanb at posedge.com>
> Add Power Constraint information element to Beacon and Probe Response
> frames when hostapd is configured on 5 GHz band and Country information
> element is also added. According to spec IEEE802.11-2012 a STA shall
> determine a local maximum transmit power for the current channel based
> on information derived from Country and Power Constraint elements.

How was this tested?

> +		} else if (os_strcmp(buf, "local_pwr_contraint") == 0) {
> +				conf->local_pwr_constraint = val;

> diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
> +#local_pwr_constraint=3

Note any difference in the spelling?

> +	/*
> +	 * CRDA provides reduced TX power than actual regulatory max TX power.
> +	 * Value of 0 to the local power constraint provides an opportunity
> +	 * for the client devices to operate at the power limit provided by CRDA
> +	 * (for client devices
> +	 * "Local max TX pwr" = regulatory max TX pwr - Local pwr constraint)
> +	 */

This is somewhat confusing statement in the core hostapd code which can
be used with multiple drivers, many of which are not even on Linux,
never mind use CRDA.. Why does this speak about CRDA and is this to be
understood as the functionality not working unless CRDA is used?

Jouni Malinen                                            PGP id EFC895FA

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