xhyve/qcow2: support qcow2 disk image format

[zchee]

Support QEMU qcow2 disk image format use zchee/go-qcow2.

• Alternative sparse disk image
• preadv/pwritev support (with mirage/ocaml-qcow block write)
• ocaml-qcow: OCaml to C binding to cgo use Go .syso build
  • .ml -> .cmx -> .o -> .syso -> cgo
• Fully compatible Docker for Mac's Docker.qcow2 qcow2 option
  • hardcoded
  • cluster-size: 65536
  • preallocation: false(off)
  • AES encryption: false(no encryption)
  • lazy-refcount: true(on)
• diskimageFooter/efipartfooter
  • []byte hardcoded "SFH...disk image" "EFI PART" magic string
  • See strings /path/to/qcow2image.qcow2 or any binary editor

    build

    Install ocaml-qcow:

https://github.com/docker/hyperkit#building

make

GO_BUILD_TAG='lib9p qcow2' make V=1

check

make test-bindings or

• lib9p: nm bin/docker-machine-driver-xhyve | grep _l9p_server_init
• qcow2: nm bin/docker-machine-driver-xhyve | grep _camlMirage_block__code_begin

[zchee]

/cc @dlorenc @r2d4 Please test it if you have time. If you can't build with any problems, I will upload pre-compile binary.

[dlorenc]

I've been trying to build but running into problems with homebrew/opam. I'll keep trying today.

[r2d4]

-> ls ~/.minikube/machines/minikube/minikube.qcow2
/Users/mrick/.minikube/machines/minikube/minikube.qcow2

Works with minikube on my machine! 👍

[dlorenc]

Feel free to merge :) @r2d4 tested and it works for him :)

[zchee]

@dlorenc I see :) I will merge it after the fix some issue(go test, travis build).

[zchee]

@r2d4 and, Thanks for test! It might be difficult to build from source because of OCaml dependency, so I will release pre-build binary as soon as possible.