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History

Erik Schilling 2b1b3644da tree-wide: drop the Eq trait from Error I plan to add some wrapper errors around vhost errors. These end up nesting other errors all the way to std::error::Error, which has no Eq trait. The implementations were only used for comparisions in tests. While there is a assert_matches!() in nightly [1] it seems unlikely that further testing lib additions are getting standarized soon (or ever). One could use assert!(matches!()), but that would worsen the error messages for test failures. Hence, during review [2] we agreed on introducing the assert_matches crate. It got no dependencies and allows us to keep the good error messages while not needing to depend on nightly. Signed-off-by: Erik Schilling <erik.schilling@linaro.org> [1] https://doc.rust-lang.org/std/assert_matches/macro.assert_matches.html [2] https://github.com/rust-vmm/vhost-device/pull/388#discussion_r1257831748		2023-07-11 13:30:01 +05:30
..
src	tree-wide: drop the Eq trait from Error	2023-07-11 13:30:01 +05:30
test	scsi: mention out-of-tree fuzzing infrastructure	2023-06-05 14:55:32 +05:30
ARCHITECTURE.md	scsi: Add documentation	2023-06-05 14:55:32 +05:30
Cargo.toml	tree-wide: drop the Eq trait from Error	2023-07-11 13:30:01 +05:30
CHANGELOG.md	Add CHANGELOG.md to all crates	2023-07-07 22:06:45 +05:30
LICENSE-APACHE	Symlink license files into crate folders	2023-07-04 14:56:52 +05:30
LICENSE-BSD-3-Clause	Symlink license files into crate folders	2023-07-04 14:56:52 +05:30
README.md	scsi: Add documentation	2023-06-05 14:55:32 +05:30

README.md

vhost-user-scsi

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

Usage

Run the vhost-user-scsi daemon:

vhost-user-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.