man: document that changing --uid= doesn't work

Fixes: #28982

diff --git a/man/homectl.xml b/man/homectl.xml
index 1cfbdcd4f83c43d16bd2a633671ccf2494c00243..7fc7d5f01223c0a9daec021c0d931ec3622ba44a 100644 (file)
--- a/man/homectl.xml
+++ b/man/homectl.xml
@@ -269,6 +269,11 @@
         owned by a different UID when logging in, the home directory and everything underneath it will have
         its ownership changed automatically before login completes.</para>
 
+        <para>Note that changing this option for existing home directories generally has no effect on home
+        directories that already have been registered locally (have a local <emphasis>binding</emphasis>), as
+        the UID used for an account on the local system is determined when the home directory is first
+        activated on it, and then remains in effect until the home directory is removed.</para>
+
         <para>Note that users managed by <command>systemd-homed</command> always have a matching group
         associated with the same name as well as a GID matching the UID of the user. Thus, configuring the
         GID separately is not permitted.</para>