I have spent a few hours over the last 3 days trying to work out why hostapd 1.0 on a custom built buildroot image wouldn’t work with an Realtek 8192 usb wireless card in AP mode while using the vendor driver. It turns out that this driver comes bundled with an alternative hostapd. The bundled hostapd comes with a new driver named rtl871xdrv, which does not exist in the public version (At least, up to 1.0, AFAICT.) In order to get this to work, we must compile the hostapd supplied using a .config that contains a line that reads like: CONFIG_DRIVER_RTW=y

Then, once built, it should be straight-forward to test and setup an Access Point using your usb-wireless nic. I have used this hostapd configuration to test it:

    interface=wlan0
#bridge=br0
driver=rtl871xdrv
ssid=SampleNetwork
hw_mode=g
channel=11