diff --git a/image-base.yaml b/image-base.yaml
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+# This file is shared by all streams. For a stream-specific change, use
+# image.yaml instead.
+
+# Target disk size in GB.
+# Make it at least 10G because we want the rootfs to be at least 8G:
+# https://github.com/coreos/fedora-coreos-tracker/issues/586
+size: 10
+
+extra-kargs:
+    # Disable SMT on systems vulnerable to MDS or any similar future issue.
+    - mitigations=auto,nosmt
+
+# Disable networking by default on firstboot. We can drop this once cosa stops
+# defaulting to `ip=auto rd.neednet=1` when it doesn't see this key.
+ignition-network-kcmdline: []
+
+# Optional remote by which to prefix the deployed OSTree ref
+ostree-remote: fedora
+
+# opt in to using the `metadata_csum_seed` feature of the ext4 filesystem
+# for the /boot filesystem. Support for this was only recently added to grub
+# and isn't available everywhere yet so we'll gate it behind this image.yaml
+# knob. It should be easy to know when RHEL/RHCOS supports this by just flipping
+# this to `true` and doing a build. It should error when building the disk
+# images if grub doesn't support it.
+# https://lists.gnu.org/archive/html/grub-devel/2021-06/msg00031.html
+bootfs_metadata_csum_seed: true
+
+vmware-os-type: fedora64Guest
+# VMware hardware versions: https://kb.vmware.com/s/article/1003746
+# We use the newest version allowed by the oldest non-EOL VMware
+# Workstation/Player/Fusion/ESXi release: https://lifecycle.vmware.com/
+vmware-hw-version: 13
+
+# After this, we plan to add support for the Ignition
+# storage/filesystems sections.  (Although one can do
+# that on boot as well)
diff --git a/image.yaml b/image.yaml
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+include: image-base.yaml