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Manos Pitsidianakis a1e013286f Move all crates to workspace root Having all the workspace crates under the crates/ directory is unnecessary. Rust documentation itself recommends all crates to be in the root directory: https://doc.rust-lang.org/book/ch14-03-cargo-workspaces.html#creating-the-second-package-in-the-workspace I paste the text content here, in case the online page ever changes or becomes unavailable: ## Creating the Second Package in the Workspace Next, let’s create another member package in the workspace and call it add_one. Change the top-level Cargo.toml to specify the add_one path in the members list: Filename: Cargo.toml [workspace] members = [ "adder", "add_one", ] Then generate a new library crate named add_one: $ cargo new add_one --lib Created library `add_one` package Your add directory should now have these directories and files: ├── Cargo.lock ├── Cargo.toml ├── add_one │ ├── Cargo.toml │ └── src │ └── lib.rs ├── adder │ ├── Cargo.toml │ └── src │ └── main.rs └── target Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>		2023-10-16 12:03:57 +05:30
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test	Move all crates to workspace root	2023-10-16 12:03:57 +05:30
ARCHITECTURE.md	Move all crates to workspace root	2023-10-16 12:03:57 +05:30
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CHANGELOG.md	Move all crates to workspace root	2023-10-16 12:03:57 +05:30
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README.md	Move all crates to workspace root	2023-10-16 12:03:57 +05:30

README.md

vhost-device-scsi

This is a Rust implementation of a vhost-device-scsi daemon.

Usage

Run the vhost-device-scsi daemon:

vhost-device-scsi -r --socket-path /tmp/vhost-user-scsi.sock /path/to/image.raw /path/to/second-image.raw ...

Run QEMU:

qemu-system-x86_64 ... \
  -device vhost-user-scsi-pci,num_queues=1,param_change=off,chardev=vus \
  -chardev socket,id=vus,path=/tmp/vhost-user-scsi.sock \
  # must match total guest meory
  -object memory-backend-memfd,id=mem,size=384M,share=on \
  -numa node,memdev=mem

Limitations

We are currently only supporting a single request queue and do not support dynamic reconfiguration of LUN parameters (VIRTIO_SCSI_F_CHANGE).

Features

This crate is a work-in-progress. Currently, it's possible to mount and read up to 256 read-only raw disk images. Some features we might like to add at some point, roughly ordered from sooner to later:

Write support. This should just be a matter of implementing the WRITE command, but there's a bit of complexity around writeback caching we need to make sure we get right.
Support more LUNs. virtio-scsi supports up to 16384 LUNs per target. After 256, the LUN encoding format is different; it's nothing too complicated, but I haven't gotten around to implementing it.
Concurrency. Currently, we process SCSI commands one at a time. Eventually, it'd be a good idea to use threads or some fancy async/io_uring stuff to concurrently handle multiple commands. virtio-scsi also allows for multiple request queues, allowing the guest to submit requests from multiple cores in parallel; we should support that.
iSCSI passthrough. This shouldn't be too bad, but it might be a good idea to decide on a concurrency model (threads or async) before we spend too much time here.