A tarball for a generic nfsroot for arm64 can be found at

https://fai-project.org/download/misc/

You can extract it on any x86 server and serve it to your arm64
clients via NFS. Do not forget to adjust the etc/hosts and
etc/resolv.conf files inside the nfsroot. fai-make-nfsroot -a may
help you.

-- 
regards Thomas

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