$ pwd
/home/tony/scratch/opam/test-opam-root
$ opam init --reinit --bare --no-setup --root $PWD opam.ocaml.org https://opam.ocaml.org
$ opam repository add --root $PWD satysfi-external https://github.com/gfngfn/satysfi-external-repo.git
$ opam repository add --root $PWD opam-windows-repository https://github.com/vouillon/opam-windows-repository.git
$ opam repository add --root $PWD ocamlbench-repo https://github.com/OCamlPro/ocamlbench-repo.git
$ opam repo --all --root $PWD
# Repository            # Url                                                       # Switches(rank)
ocamlbench-repo         git+https://github.com/OCamlPro/ocamlbench-repo.git
opam-windows-repository git+https://github.com/vouillon/opam-windows-repository.git
opam.ocaml.org          https://opam.ocaml.org                                      <default>(1)
satysfi-external        git+https://github.com/gfngfn/satysfi-external-repo.git
$ du -sh
247M    .
$ opam list --all --root $PWD --repos ocamlbench-repo
# Packages matching: any
# Name                   # Installed # Synopsis
all-bench                --          Meta packages triggering the installation of all macro-benchmark packages.
almabench-bench          --          A number-crunching benchmark designed for cross-language and vendor comparisons
alt-ergo-bench           --
async-echo-bench         --
async-rpc-bench          --
async-smtp-bench         --          Sending and receiving n emails with async_smtp
bdd-bench                --          BDD benchmark.
camlp4                   --
chameneos-bench          --          See http://benchmarksgame.alioth.debian.org/u64/performance.php?test=chameneosredux#about
cohttp-bench             --
compcert                 --          The CompCert C compiler.
compcert-bench           --          Compcert benchmark (on its raytracer tests).
coq-bench                --
core-micro-bench         --
core-sequence-bench      --          Iterator composition benchmark
core-tests-bench         --
cpdf-bench               --          Tests on cpdf on some big file operations
frama-c-bench            --
js_of_ocaml-bench        --
json-bench-data          --
jsonm-bench              --
kb-bench                 --          Knuth-Bendix completion algorith benchmark
lexifi-g2pp-bench        --          A simplified and stripped down version of LexiFi's calibration routine for the G2++ model
macrobenchmarks          --
macrobenchmarks-test     --          Building this package run various tests
menhir-bench             --
minilight-bench          --          Minilight benchmark.
nbcodec                  --          non-blocking IO interface design
nbcodec-bench            --          Non-blocking codec for S-expressions
numerical-analysis-bench --          Collection of small programs for numerical analysis (bench)
ocaml                    --          The OCaml compiler (virtual package)
ocaml-variants           --
patdiff-bench            --
ppx_tools                --          Tools for authors of ppx rewriters and other syntactic tools
sauvola-bench            --          Functions to enhance contrast of scanned images in OCaml (Benchmark)
sequence-bench           --
thread-bench             --          Lwt/Async scheduler benchmarks
valet-bench              --          Simulation of an access control system
yojson-bench             --