packet: Add inte-ucode.cpio to packet example

and override it for the arm64 add on

Signed-off-by: Rolf Neugebauer <rolf.neugebauer@docker.com>

examples/packet.arm64.yml

@@ -1,3 +1,13 @@
+# This YAML snippet is to be used in conjunction with packet.yml to
+# build a arm64 image for packet.net. It adds a modprobe of the NIC
+# driver and overrides the kernel section to disable prepending the
+# Intel CPU microcode to the initrd. If writing a YAML specifically
+# for arm64 then the 'ucode' line in the kernel section can be left
+# out.
+kernel:
+  image: linuxkit/kernel:4.9.76
+  cmdline: "console=ttyAMA0"
+  ucode: ""
 onboot:
   - name: modprobe
     image: linuxkit/modprobe:1a192d168adadec47afa860e3fc874fbc2a823ff

examples/packet.yml

@@ -1,6 +1,7 @@
 kernel:
   image: linuxkit/kernel:4.9.76
-  cmdline: "console=ttyS1 console=ttyAMA0"
+  cmdline: console=ttyS1
+  ucode: intel-ucode.cpio
 init:
   - linuxkit/init:f7a3d03face99e933626533a3381ae4476fbc8de
   - linuxkit/runc:7b15b00b4e3507d62e3ed8d44dfe650561cd35ff