On Thu, Sep 24, 2009 at 1:55 AM, Holger Schurig
<hs4233@xxxxxxxxxxxxxxxxxxxx> wrote:
> Linux keeps scan results up to 15 seconds. This can be a problem for fast
> moving client: they get back stale data. But if the kernel reports the
> age of some BSS, then user-space can simply weed out old entries.
>
> Signed-off-by: Holger Schurig <hs4233@xxxxxxxxxxxxxxxxxxxx>
>
> ---
>
> One question was if I should specify the age in ms, or if I should specify
> an absolute time. In the end I thought age in ms is better suited.
>
> If an absolute time would sent with every BSS item, then user-space would
> need an additional call to time() to find out which BSS items are too old.
> Now it can use the milliseconds directly.
>
> The case there user-space wants an absolute time ("At what hour did I get
> the last probe response from this AP?") seems to be a more theoretical
> problem. But if info is wanted, *THEN* you can call time() and substract the
> reported bss-item-age from it.
>
>
> Index: linux-wl/include/linux/nl80211.h
> ===================================================================
> --- linux-wl.orig/include/linux/nl80211.h 2009-09-24 09:19:03.000000000 +0200
> +++ linux-wl/include/linux/nl80211.h 2009-09-24 09:19:42.000000000 +0200
> @@ -1277,6 +1277,7 @@ enum nl80211_channel_type {
> * @NL80211_BSS_SIGNAL_UNSPEC: signal strength of the probe response/beacon
> * in unspecified units, scaled to 0..100 (u8)
> * @NL80211_BSS_STATUS: status, if this BSS is "used"
> + * @NL80211_BSS_AGE_MS: age of this BSS entry in ms
> * @__NL80211_BSS_AFTER_LAST: internal
> * @NL80211_BSS_MAX: highest BSS attribute
> */
> @@ -1291,6 +1292,7 @@ enum nl80211_bss {
> NL80211_BSS_SIGNAL_MBM,
> NL80211_BSS_SIGNAL_UNSPEC,
> NL80211_BSS_STATUS,
> + NL80211_BSS_AGE_MS,
Wil want to #define NL80211_BSS_AGE_MS NL80211_BSS_AGE_MS as well so
userspace apps can ifdef around that feature to know if its supported.
Luis
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