Merge pull request #6438 from poettering/distro-porting-more

extend README and DISTRO_PORTING a bit

DISTRO_PORTING

@@ -15,6 +15,7 @@ HOWTO:
             -D setfont-path=
             -D tty-gid=
             -D ntp-servers=
+            -D dns-servers=
             -D support-url=
 
         2) Try it out. Play around (as an ordinary user) with
@@ -24,11 +25,10 @@ HOWTO:
         This will also inform you about ordering loops and suchlike.
 
 NTP POOL:
-
-        By default, timesyncd uses the Google Public NTP servers
-        time[1-4].google.com. They serve time that uses a leap second
-        smear, and can be up to .5s off from servers that use stepped
-        leap seconds.
+        By default, systemd-timesyncd uses the Google Public NTP servers
+        time[1-4].google.com, if no other NTP configuration is available. They
+        serve time that uses a leap second smear, and can be up to .5s off from
+        servers that use stepped leap seconds.
 
         https://developers.google.com/time/smear
 
@@ -39,6 +39,17 @@ NTP POOL:
 
         http://www.pool.ntp.org/en/vendors.html
 
+        Use -D ntp-servers= to direct systemd-timesyncd to different fallback
+        NTP servers.
+
+DNS SERVERS:
+        By default, systemd-resolved uses the Google Public DNS servers
+        8.8.8.8, 8.8.4.4, 2001:4860:4860::8888, 2001:4860:4860::8844 as
+        fallback, if no other DNS configuration is available.
+
+        Use -D dns-servers= to direct systemd-resolved to different fallback
+        DNS servers.
+
 PAM:
         The default PAM config shipped by systemd is really bare bones.
         It does not include many modules your distro might want to enable
@@ -50,7 +61,6 @@ PAM:
         instead install your own.
 
 CONTRIBUTING UPSTREAM:
-
         We generally do no longer accept distribution-specific patches to
         systemd upstream. If you have to make changes to systemd's source code
         to make it work on your distribution, unless your code is generic

README

@@ -107,6 +107,15 @@ REQUIREMENTS:
         fixed, and it's best to disable group scheduling hence.
            CONFIG_RT_GROUP_SCHED=n
 
+        It's a good idea to disable the implicit creation of networking bonding
+        devices by the kernel networking bonding module, so that the
+        automatically created "bond0" interface doesn't conflict with any such
+        device created by systemd-networkd (or other tools). Please make sure
+        that the kernel module bonding.ko is shipped with max_bonds=0 set by
+        default. Ideally there would be a kernel compile-time option for this,
+        but there currently isn't. The next best thing is to make this change
+        through a modprobe.d drop-in.
+
         Note that kernel auditing is broken when used with systemd's
         container code. When using systemd in conjunction with
         containers, please make sure to either turn off auditing at