networkd: clarify that IPv6 RA uses our own stack, no the kernel's

Fixes: #8906

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index 5a83314332fe116d08476699086a7c1e773f2466..19e4f59edd8ca9aea763a782b994da01308dd106 100644 (file)
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -630,6 +630,11 @@
           url="https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt">ip-sysctl.txt</ulink> in the kernel
           documentation regarding <literal>accept_ra</literal>, but note that systemd's setting of
           <constant>1</constant> (i.e. true) corresponds to kernel's setting of <constant>2</constant>.</para>
+
+          <para>Note that if this option is enabled a userspace implementation of the IPv6 RA protocol is
+          used, and the kernel's own implementation remains disabled, since `networkd` needs to know all
+          details supplied in the advertisements, and these are not available from the kernel if the kernel's
+          own implemenation is used.</para>
         </listitem>
         </varlistentry>
         <varlistentry>