Add new workspace under staging/ subdirectory

Add a new workspace for devices that have no final specification merged
into the virtio spec.

Closes #459

Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>

README.md

@@ -15,6 +15,22 @@ Here is the list of device backends that we support:
 - [SCSI](https://github.com/rust-vmm/vhost-device/blob/main/crates/vhost-device-scsi/README.md)
 - [VSOCK](https://github.com/rust-vmm/vhost-device/blob/main/crates/vhost-device-vsock/README.md)
 
+For `vhost-user` device backends that have no final specification merged into
+the [VIRTIO specification](https://github.com/oasis-tcs/virtio-spec), or have partial functionality, we have a [staging
+workspace](./staging/).
+More information may be found in its [README file](./staging/README.md).
+
+Here is the list of device backends in **staging**:
+
+- Currently none.
+
+<!--
+Template:
+
+- [`_DEVICE_NAME_`](https://github.com/rust-vmm/vhost-device/blob/main/staging/vhost-device-_DEVICE_NAME_/README.md)
+
+-->
+
 ## Testing and Code Coverage
 
 Like the wider rust-vmm project we expect new features to come with

staging/.gitignore

@@ -0,0 +1 @@
+target/

staging/Cargo.toml

@@ -0,0 +1,3 @@
+[workspace]
+resolver = "2"
+members = []

staging/README.md

@@ -0,0 +1,17 @@
+# vhost-device `staging` workspace
+
+This directory includes a separate Cargo workspace to include working vhost-user backend implementations that concern devices that have partial functionality and devices (and/or functionality) not yet ratified in the [VIRTIO specification](https://github.com/oasis-tcs/virtio-spec).
+For more details about vhost-device you can refer to the repository [README](../README.md).
+
+To add a new member crate:
+
+1. Place it under this directory, [`./staging`](../staging).
+2. Append its name in the `workspace.members` array field of [the workspace manifest file](./Cargo.toml).
+3. Update the crate list in the repository [README](../README.md).
+
+## Testing and Continuous Integration
+
+ℹ️  **Notice** ℹ️ : The CI runs on the root workspace only.
+This means that `staging` crates can have failing tests and bring down code coverage without automatic checks.
+Tests can still be run locally as part of the development process.
+To add a crate to the CI, add it to the root `Cargo.toml` `workspace.members` array as well as the `staging` manifest.