[systemd-devel] udev breaks hostap linkage of raw/user interfaces, causing wpa_supplicant problems

Greg KH greg at kroah.com
Mon Mar 16 01:04:53 PDT 2015

On Mon, Mar 16, 2015 at 08:26:00AM +0100, Thomas Richter wrote:
> Hi folks,
> > udev seems to create a problem here with the hostap (prism2) kernel
> > driver. Unlike many wifi devices, the hostap device driver always
> > creates paired interfaces, a raw interface (wifiX) and a network
> > interface (wlanX) that represents the configured network.
> > 
> > Unfortunately, udev (or hostap?) does not seem to be aware of this
> > linkage, and hence, if you have two wifi radios in your system, may
> > rename the second (wlanX) without the first (wifiX), and hence causing a
> > name mismatch between the two.
> > 
> > In general, this is not a problem, however, wpa_supplicant seems to
> > depend on the linkage of the names. Hence, if wifiX does not match
> > wlanX, wpa_supplicant will be unable to provide a WPA2 connection over a
> > hostap driven wifi connection.
> > 
> > Even worse, the complete procedure is completely untransparent to the
> > user, i.e. neither wpa_supplicant (nor network-manager, depending on
> > wpa_supplicant) nor network-manager provide a useful error message.
> > 
> > Any chance of fixing this problem? Is this "only" a configuration issue?
> > Is this an issue of hostap? Is this an issue of wpa_supplicant?
> > 
> > Either way, it took me several hours of figuring out what was wrong....
> One day passed, no useful pointers. Folks, sorry to say, but it is
> unacceptable if udev *breaks* the prism wifi.

A Sunday passed, and you are upset that no one fixed a problem for an
obsolete kernel driver?  What kind of free software support are you used

Anyway, which exact kernel driver is this?  Is it prism2_usb?  Or
something else?


greg k-h

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