mirror of
https://github.com/rust-vmm/vhost-device.git
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76 lines
3.1 KiB
Markdown
76 lines
3.1 KiB
Markdown
# vhost-device
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## Design
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This repository hosts various 'vhost-user' device backends in their own crates.
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See their individual README.md files for specific information about those
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crates.
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Here is the list of device backends that we support:
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- [GPIO](https://github.com/rust-vmm/vhost-device/blob/main/crates/gpio/README.md)
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- [I2C](https://github.com/rust-vmm/vhost-device/blob/main/crates/i2c/README.md)
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- [RNG](https://github.com/rust-vmm/vhost-device/blob/main/crates/rng/README.md)
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- [SCMI](https://github.com/rust-vmm/vhost-device/blob/main/crates/scmi/README.md)
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- [SCSI](https://github.com/rust-vmm/vhost-device/blob/main/crates/scsi/README.md)
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- [VSOCK](https://github.com/rust-vmm/vhost-device/blob/main/crates/vsock/README.md)
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## Testing and Code Coverage
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Like the wider rust-vmm project we expect new features to come with
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comprehensive code coverage. However as a multi-binary repository
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there are cases where avoiding a drop in coverage can be hard and an
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exception to the approach is allowable. These are:
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* adding a new binary target (aim at least 60% overall coverage)
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* expanding the main function (a small drop is acceptable)
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However any new feature added to an existing binary should not cause a
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drop in coverage. The general aim should be to always improve
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coverage.
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## Separation of Concerns
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The binaries built by this repository can be run with any VMM which
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can act as a vhost-user frontend. Typically they have been tested with
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[QEMU](https://www.qemu.org) although the rust-vmm project does
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provide a [vhost-user
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frontend](https://github.com/rust-vmm/vhost/tree/main/src/vhost_user)
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crate for rust based VMMs.
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While it's possible to implement all parts of the backend inside the
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vhost-device workspace consideration should be given to separating the
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VirtQueue handling and response logic to a crate in [vm-virtio
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devices](https://github.com/rust-vmm/vm-virtio/tree/main/crates/devices).
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This way a monolithic rust-vmm VMM implementation can reuse the core
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logic to service the virtio requests directly in the application.
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## Build dependency
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The GPIO crate needs a local installation of libgpiod library to be available.
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If your distro ships libgpiod >= v2.0, then you should be fine.
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Otherwise, you will need to build libgpiod yourself:
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git clone --depth 1 --branch v2.0.x https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/
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cd libgpiod
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./autogen.sh --prefix="$PWD/install/"
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make install
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In order to inform tools about the build location, you can now set:
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export PKG_CONFIG_PATH="<PATH-TO-LIBGPIOD>/install/lib/pkgconfig/"
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To prevent setting this in every terminal session, you can also configure
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cargo to
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[set it automatically](https://doc.rust-lang.org/cargo/reference/config.html#env).
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## Xen support
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Supporting Xen requires special handling while mapping the guest memory. The
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`vm-memory` crate implements xen memory mapping support via a separate feature
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`xen`, and this crate uses the same feature name to enable Xen support.
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It was decided by the `rust-vmm` maintainers to keep the interface simple and
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build the crate for either standard Unix memory mapping or Xen, and not both.
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