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--- doc:appunti:hardware:raspberrypi_wpa_supplicant_problem [2024/11/15 15:06] – [dhcpcd process dies without configuring wlan0] niccolo
+++ doc:appunti:hardware:raspberrypi_wpa_supplicant_problem [2024/11/17 16:55] (current) – [dhcpcd process dies without configuring wlan0] niccolo
@@ Line 112: / Line 112: @@
 It results that wlan0 gets a sqeuence of ''wlan0: carrier acquired'' and ''wlan0: carrier lost'', after that the fatal error **main: eloop_start: Invalid argument** kills dhcpcd. Maybe this problem is triggered by the autoconfiguration of IPv6.
-I solved the problem by letting Systemd to start wpa_supplicant on the specific wlan0 interface. This is achieved renaming the wpa_supplicant.conf file and enabling the service:
+I solved the problem by letting Systemd to start wpa_supplicant on the specific wlan0 interface. This is achieved renaming the wpa_supplicant.conf file and enabling only the interface-specific version service:
 <code>
 mv /etc/wpa_supplicant/wpa_supplicant.conf /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
 systemctl enable wpa_supplicant@wlan0.service
+systemctl disable wpa_supplicant.service
 </code>
@@ Line 135: / Line 136: @@
 Nevertehless dhcpcd is informed by udev when the wlan0 interface is activated and then it can configure it using DHCP.
-**NOTICE**: The default systemd configuration shipped with **Raspbian 11 Bullseye** does not ensure that the **wpa_supplicant@.service** is started before **dhcpcd.service**, thus ensuring that the above startup sequence is respected. You can generate the SVG graphic detailing which system services have been started at what time using the command:
+**NOTICE**: The default systemd configuration shipped with **Raspbian 11 Bullseye** does not ensure that the **wpa_supplicant@..service** is started before **dhcpcd.service**, thus ensuring that the above startup sequence is respected. You can generate the SVG graphic detailing which system services have been started at what time using the command:
 <code>
@@ Line 141: / Line 142: @@
 </code>
-Indeed you can see that **dhcpcd.service** is started before **wpa_supplicant@wlan0.service**. We should customize the dhcpcd.service unit adding a **Before=wpa_supplicant@..service** option. FIXME.
+Indeed you can see that **dhcpcd.service** becomes active after the **wpa_supplicant@wlan0.service**, but nothing is ensuring this behaviour. We should actually customize the dhcpcd.service unit adding an **After=wpa_supplicant@..service** option. For this purpose we use the command **systemctl edit**:
+<code>
+systemctl edit dhcpcd.service
+</code>
+this will launch an editor to create the file **/etc/systemd/system/dhcpcd.service.d/override.conf**; this is a drop-in snippet to extend or override the definition of the unit. Here we write:
+<file>
+[Unit]
+After=wpa_supplicant@..service
+</file>
+The systemd daemon will be automatically reloaded, se we can reboot.
 ===== Web References =====
   * [[https://www.raspberrypi.org/forums/viewtopic.php?t=191061|Raspbian Stretch: Wifi not starting on boot]]