virtio-bindings: drop bindings for older kernels

crates/virtio-bindings/CONTRIBUTING.md

@@ -17,29 +17,18 @@ repository on your machine:
 git clone https://github.com/torvalds/linux.git
 ```
 
-## Example for adding a new version
+## Example for updating to a new kernel version
 
 For this example we assume that you have both linux and virtio-bindings
 repositories in your root.
 
 ```bash
-# Step 1: Create a new module using a name with format "bindings_vVERSION" in
-# src/
-cd vm-virtio/crates/virtio-bindings
-mkdir src/bindings_v5_0_0
-cd ~
-
-# Step 2: Copy the "mod.rs" file from the directory of an already existing
-# version module to the one we've just created.
-cd vm-virtio/crates/virtio-bindings/src
-cp bindings_v4_14_0/mod.rs bindings_v5_0_0/mod.rs
-
 # linux is the repository that you cloned at the previous step.
 cd linux
-# Step 3: Checkout the version you want to generate the bindings for.
+# Step 1: Checkout the version you want to generate the bindings for.
 git checkout v5.0
 
-# Step 4: Generate the bindings from the kernel headers. We need to
+# Step 2: Generate the bindings from the kernel headers. We need to
 # generate a file for each one of the virtio headers we're interested on.
 # For the moment, we're generating "virtio_blk", "virtio_net" and
 # "virtio_ring". Feel free to add additional header files if you need them
@@ -55,16 +44,5 @@ done
 cd ~
 
 # Step 6: Copy the generated files to the new version module.
-cp linux/v5_0_headers/*.rs vm-virtio/crates/virtio-bindings/src/bindings_v5_0_0
-```
-
-Once this is done, edit the generated files to add the proper license header,
-and add the new version module to `vm-virtio/crates/virtio-bindings/lib.rs`. If
-this version is newer than the others already present, make this version the
-default one by getting it imported when there isn't any other version specified
-as a feature:
-
-```rust
-#[cfg(all(not(feature = "virtio-v4_14_0"), not(feature = "virtio-v5_0_0")))]
-pub use super::bindings_v5_0_0::*;
+cp linux/v5_0_headers/*.rs vm-virtio/crates/virtio-bindings/src
 ```

crates/virtio-bindings/Cargo.toml

@@ -9,6 +9,10 @@ edition = "2021"
 keywords = ["virtio"]
 license = "BSD-3-Clause OR Apache-2.0"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+# Kernel version features are deprecated and no longer have any effect,
+# as the kernel headers are backwards compatible.
+virtio-v4_14_0 = []
+virtio-v5_0_0 = []
 
 [dependencies]

crates/virtio-bindings/README.md

@@ -4,13 +4,10 @@ Rust FFI bindings to virtio generated using [bindgen](https://crates.io/crates/b
 # Usage
 Add this to your `Cargo.toml`:
 ```toml
-virtio-bindings = { version = "0.1", features = ["virtio-v5_0_0"]}
+virtio-bindings = "0.1"
 ```
 You can then import the bindings where you need them. As an example, to grab the
 bindings for virtio-blk, you can do:
 ```rust
 use virtio_bindings::bindings::virtio_blk::*;
 ```
-In the `virtio-bindings` crate each feature maps to exactly one Linux version as follows:
-- `virtio-v4_14_0` contains the bindings for the Linux kernel version 4.14
-- `virtio-v5_0_0` contains the bindings for the Linux kernel version 5.0