man: extend Personality= docs a bit

Let's make clear personalities are supported on ARM (as per
https://github.com/systemd/systemd/pull/26152#issuecomment-1400321944).

Also, clarify that on many archs this functionality is pretty pointless,
i.e. where only a single native arch was ever known.

diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
index 0bb5569c331df71ca5510668116e225f951c62d2..b6e71cce2ba51754a9f8190f01261e8ea05b269d 100644 (file)
--- a/man/systemd.exec.xml
+++ b/man/systemd.exec.xml
@@ -1088,16 +1088,20 @@ CapabilityBoundingSet=~CAP_B CAP_C</programlisting>
         <term><varname>Personality=</varname></term>
 
         <listitem><para>Controls which kernel architecture <citerefentry
-        project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry> shall report,
-        when invoked by unit processes. Takes one of the architecture identifiers <constant>x86</constant>,
-        <constant>x86-64</constant>, <constant>ppc</constant>, <constant>ppc-le</constant>, <constant>ppc64</constant>,
-        <constant>ppc64-le</constant>, <constant>s390</constant> or <constant>s390x</constant>. Which personality
-        architectures are supported depends on the system architecture. Usually the 64bit versions of the various
-        system architectures support their immediate 32bit personality architecture counterpart, but no others. For
-        example, <constant>x86-64</constant> systems support the <constant>x86-64</constant> and
-        <constant>x86</constant> personalities but no others. The personality feature is useful when running 32-bit
-        services on a 64-bit host system. If not specified, the personality is left unmodified and thus reflects the
-        personality of the host system's kernel.</para></listitem>
+        project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry> shall
+        report, when invoked by unit processes. Takes one of the architecture identifiers
+        <constant>arm64</constant>, <constant>arm64-be</constant>, <constant>arm</constant>,
+        <constant>arm-be</constant>, <constant>x86</constant>, <constant>x86-64</constant>,
+        <constant>ppc</constant>, <constant>ppc-le</constant>, <constant>ppc64</constant>,
+        <constant>ppc64-le</constant>, <constant>s390</constant> or <constant>s390x</constant>. Which
+        personality architectures are supported depends on the kernel's native architecture. Usually the
+        64bit versions of the various system architectures support their immediate 32bit personality
+        architecture counterpart, but no others. For example, <constant>x86-64</constant> systems support the
+        <constant>x86-64</constant> and <constant>x86</constant> personalities but no others. The personality
+        feature is useful when running 32-bit services on a 64-bit host system. If not specified, the
+        personality is left unmodified and thus reflects the personality of the host system's kernel. This
+        option is not useful on architectures for which only one native word width was ever available, such
+        as <constant>m68k</constant> (32bit only) or <constant>alpha</constant> (64bit only).</para></listitem>
       </varlistentry>
 
       <varlistentry>