man: document LoaderEntryLastBooted

The option was introduced with systemd v250 although it went
undocumented. It effectively sits between Default and OneShot, in term
of priority.

It is repeatedly updated as long as loader.conf default is "@saved" and
the OneShot is not set.

v2:
 - squash some typos

v3:
 - special mention to default @saved + loader.conf reference
 - reword update side, to avoid misleading that it's needlessly
   overwritten

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

diff --git a/man/systemd-boot.xml b/man/systemd-boot.xml
index 67208806f97ebe33c5209a8197e04ddd33f23479..b6efd8927c937ca1a17c0e7a5a93e32fd4491415 100644 (file)
--- a/man/systemd-boot.xml
+++ b/man/systemd-boot.xml
@@ -461,6 +461,27 @@
         <xi:include href="version-info.xml" xpointer="v240"/></listitem>
       </varlistentry>
 
+      <varlistentry>
+        <term><varname>LoaderEntryLastBooted</varname></term>
+
+        <listitem><para>The identifier of the boot loader entry last attempted. Set and read by the boot loader,
+        only when <filename>/loader/loader.conf</filename> has default set to <literal>@saved</literal>. See
+        <citerefentry><refentrytitle>loader.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+
+        <para> The boot loader will ensure <varname>LoaderEntryLastBooted</varname> is up-to date for every boot,
+        updating it as needed and will omit changing it all together when <varname>LoaderEntryOneShot</varname>
+        is set.</para>
+
+        <para>The boot loader reads the variable, which takes higher priority than
+        <varname>LoaderEntryDefault</varname>. The variable is ignored when <varname>LoaderEntryOneShot</varname>
+        is set.</para>
+
+        <para><varname>LoaderEntryLastBooted</varname> cannot be used as indication that the last boot was
+        successful or not.</para>
+
+        <xi:include href="version-info.xml" xpointer="v250"/></listitem>
+      </varlistentry>
+
       <varlistentry>
         <term><varname>LoaderEntrySelected</varname></term>