#4506: Fix systemd-networkd to work with 5.2+ kernels
--------------------+----------------------
 Reporter:  renodr  |      Owner:  lfs-book
     Type:  defect  |     Status:  new
 Priority:  normal  |  Milestone:  9.0
Component:  Book    |    Version:  SVN
 Severity:  normal  |   Keywords:
--------------------+----------------------
 In Linux Kernel 5.2+, The IPv6 implementation was changed in the kernel,
 in particular the way that it responds to calls towards it's API for
 bringing interfaces up.

 As a result, systemd-networkd will refuse to bring up any network
 interfaces that are on the system, either at startup or manually. systemd-
 networkd will return the following output:

 {{{
 enp3s0: Could not bring up interface: Invalid argument
 }}}

 You must instead bring up the interface manually through the kernel, and
 then systemd will recognize the flag change and begin bringing up DHCP
 services or assigning a static if necessary:

 {{{
 sudo ip link set enp3s0 up
 }}}

 However, as Paul Menzel from Debian noted, this isn't always guaranteed to
 work either.

 As far as I can tell (I'm running dhcpcd on my system with networkd
 brought down), dhcpcd isn't affected. I have NOT tested dhclient though,
 I'll probably do that when I'm done with this seeing as it could be
 related.

 Upstream bug report: [https://github.com/systemd/systemd/issues/12784]

 We need to apply the following patches for systemd to allow this to work:

 
[https://github.com/systemd/systemd/commit/4eb086a38712ea98faf41e075b84555b11b54362]
 
[https://github.com/systemd/systemd/commit/9f6e82e6eb3b6e73d66d00d1d6eee60691fb702f]

 On that same note, we should apply the following fix as well, for users of
 AMD Ryzen systems:

 
[https://github.com/systemd/systemd/commit/1c53d4a070edbec8ad2d384ba0014d0eb6bae077]
 
[https://github.com/systemd/systemd/commit/7f2cdceaed4d37c4e601e531c7d863fca1bd1460]
 
[https://github.com/systemd/systemd/commit/328f850e36e86d14ab06d11fa8f2397e9575a7f9]

 (This fixes issues with the Random Number Generator on Ryzen systems that
 will cause the system to fail to start due to firmware changes and the way
 that they interact with 5.2+ kernels. AMD is still preparing a firmware
 update for their CPUs to fix this. This seems to be due to the RDRAND
 instruction in AMD Excavator-era CPUs in particular).

 Upstream bug report for that:
 [https://github.com/systemd/systemd/issues/11810]

 Thank you, Wayne, for initially discovering the networkd issue:
 [http://lists.linuxfromscratch.org/pipermail/lfs-
 support/2019-July/052952.html]

--
Ticket URL: <http://wiki.linuxfromscratch.org/lfs/ticket/4506>
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