PERFORCE change 135829 for review

[Sam Leffler]

http://perforce.freebsd.org/chv.cgi?CH=135829

Change 135829 by sam at sam_ebb on 2008/02/20 19:10:14

	guard against someone bumping the # beacon buffers too high
	and leave an explanation why it's not a good idea

Affected files ...

.. //depot/projects/vap/sys/dev/ath/if_ath.c#34 edit

Differences ...

==== //depot/projects/vap/sys/dev/ath/if_ath.c#34 (text+ko) ====

@@ -84,6 +84,22 @@
 #include <dev/ath/ath_tx99/ath_tx99.h>
 #endif
 
+/*
+ * ATH_BCBUF determines the number of vap's that can transmit
+ * beacons and also (currently) the number of vap's that can
+ * have unique mac addresses/bssid.  When staggering beacons
+ * 4 is probably a good max as otherwise the beacons become
+ * very closely spaced and there is limited time for cab q traffic
+ * to go out.  You can burst beacons instead but that is not good
+ * for stations in power save and at some point you really want
+ * another radio (and channel).
+ *
+ * The limit on the number of mac addresses is tied to our use of
+ * the U/L bit and tracking addresses in a byte; it would be
+ * worthwhile to allow more for applications like proxy sta.
+ */
+CTASSERT(ATH_BCBUF <= 8);
+
 /* unaligned little endian access */
 #define LE_READ_2(p)							\
 	((u_int16_t)							\