nixos/release-notes: mention that dhcpcd stopped giving IPv4 addresses to bridges by default

This is an backward incompatible change from upstream dhcpcd [0], as
this could have easily locked me out of my box.

As dhcpcd doesn't allow to use only a blacklist (denyinterfaces in
dhcpcd.conf) of devices and use all remaining devices, while explicitly
allowing some interfaces like bridges, I think the best option would be
to not change anything about it and just educate the users here about
that edge case and how to solve it.

[0] https://roy.marples.name/archives/dhcpcd-discuss/0002621.html

(cherry picked from commit eeeb2bf8035b309a636d596de6a3b1d52ca427b1)

1 files changed, 11 insertions, 0 deletions

diff --git a/nixos/doc/manual/release-notes/rl-2003.xml b/nixos/doc/manual/release-notes/rl-2003.xml
index fb4ab1d26e8..f09fb3255d8 100644
--- a/nixos/doc/manual/release-notes/rl-2003.xml
+++ b/nixos/doc/manual/release-notes/rl-2003.xml
@@ -147,6 +147,17 @@ See https://github.com/NixOS/nixpkgs/pull/71684 for details.
   <itemizedlist>
    <listitem>
     <para>
+     The <package>dhcpcd</package> package <link xlink:href="https://roy.marples.name/archives/dhcpcd-discuss/0002621.html">
+     does not request IPv4 addresses for tap and bridge interfaces anymore by default</link>.
+     In order to still get an address on a bridge interface, one has to disable
+     <literal>networking.useDHCP</literal> and explicitly enable
+     <literal>networking.interfaces.&lt;name&gt;.useDHCP</literal> on
+     every interface, that should get an address via DHCP. This way, dhcpcd
+     is configured in an explicit way about which interface to run on.
+    </para>
+   </listitem>
+   <listitem>
+    <para>
       GnuPG is now built without support for a graphical passphrase entry
       by default. Please enable the <literal>gpg-agent</literal> user service
       via the NixOS option <literal>programs.gnupg.agent.enable</literal>.