[PATCH 2/4] Add support for AP+STA on a single radio

[Alvin Šipraga]

Hi Raphaël,

On Wed, Mar 29, 2023 at 03:44:53PM +0200, Raphaël Mélotte wrote:
> From: Felix Fietkau <nbd at nbd.name>
> 
> Although it is currently possible to have an AP (i.e. hostapd) and a STA
> (i.e. wpa_supplicant) interface running simultaneously on the same
> radio, this has severe limitations:
> 
> - If the AP is enabled first, the STA can only associate on the same
>   channel that was configured by the AP.
> - Once the STA is connected and the AP is enabled, it is no longer
>   possible to switch channels. Thus, if the BSS to which the STA is
>   associated switches channels, the connection is lost.

Isn't the issue you describe more a shortcoming of the wireless driver
rather than hostapd/wpa_supplicant? The driver is able to notify hostapd
of a channel switch on the AP interface, which might happen if a STA
sharing the same radio got connected. Some fullmac drivers behave this
way and I think it is correct. hostapd also handles it more or less OK.

Here is a quite old commit which does something to that effect:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c4f7863eae6f580a0373cbd8dc2731d082570e69

Did you consider doing something like this? I know it is not easy to
update all the drivers in the kernel...

Kind regards,
Alvin