Merge pull request #25918 from bluca/smbios_sd_notify

Support AF_VSOCK in sd_notify and pick up notify_socket from creds

man/systemd.system-credentials.xml

@@ -199,6 +199,24 @@
         </listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>vmm.notify_socket</varname></term>
+        <listitem>
+          <para>This credential is parsed looking for an <constant>AF_VSOCK</constant> or
+          <constant>AF_UNIX</constant> address where to send a <constant>READY=1</constant>
+          notification datagram when the system has finished booting. See:
+          <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+          This is useful for hypervisors/VMMs or other processes on the host
+          to receive a notification via VSOCK when a virtual machine has finished booting.
+          Note that in case the hypervisor does not support <constant>SOCK_DGRAM</constant>
+          over <constant>AF_VSOCK</constant>, <constant>SOCK_SEQPACKET</constant> will be
+          tried instead. The credential payload for <constant>AF_VSOCK</constant> should be
+          in the form: <literal>vsock:CID:PORT</literal>, where <literal>CID</literal> is
+          optional and if omitted will default to talking to the hypervisor
+          (<constant>0</constant>).</para>
+        </listitem>
+      </varlistentry>
+
     </variablelist>
   </refsect1>