Too many aps breaks wpa_supplicant

Jouni Malinen j
Fri May 23 11:51:08 PDT 2008

On Fri, May 23, 2008 at 11:43:42AM -0700, Peter Sanford wrote:

> iwlist scan reports around 150 unique access points. wpa_supplicant
> is failing with the following error:

> Scan results did not fit - trying larger buffer (131072 bytes)
> ioctl[SIOCGIWSCAN]: Argument list too long

> Is this a known issue? Can I configure the max buffer size for this
> data?

wpa_supplicant has a limit on how large a buffer it tries to use here
and it won't try to double the buffer after this 131072 bytes value.
This is the first time I've heard of such a problem with the current
limit.. Anyway, you could try increasing the limit in driver_wext.c by
changing 'res_buf_len < 100000' to 'res_buf_len < 1000000' in the
wpa_driver_wext_giwscan() function. The other option would be to use
ap_scan=2 mode where the driver is responsible for deciding which BSS to
use and wpa_supplicant would not need to receive the full scan results.

Jouni Malinen                                            PGP id EFC895FA

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