This project builds on my previous efforts to plumb the Linux Kernel Library (LKL) into USB storage devices. This time I plan on mostly ignoring Android and will instead focus on lklfuse USB support.
lklfuse uses virtio over MMIO to route block device I/O between the host block layer and LKL guest kernel. xHCI emulation appears to be how proper USB traffic routing between host and guest would normally be implemented, but I'm unfamiliar with (and daunted by) the specifications and protocols involved. Given that both guest and host are Linux, I'm considering a simpler approach using USB/IP over virtio, but would need to investigate further to see whether it's viable.
Goals
- Explore options for USB traffic routing between LKL guest and Linux hosts
- Learn about and play with the USB/IP and virtio protocols
- Read about the kernels
usbdevice_fs.hAPIs
- Implement lklfuse USB storage support
- stretch goal: map a LUKS/dm-crypt device
- stretch goal: benchmark USB against virtio-block devices
Comments
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3 months ago by dmdiss | Reply
post hack-week report:
I spent plenty of time on research, given that I wasn't very familiar with USB or virtio low-level transport and protocol details. Read original USB/IP paper: - https://www.usenix.org/legacy/events/usenix05/tech/freenix/hirofuchi/hirofuchi.pdf - USB Request Block (URB) as underlying USB/IP protocol unit appears to suit virtio-mmio transport quite well + avoids breakdown into Transfer Descriptor microframes + (isochronous) I/O scheduling complications can be initially ignored Read kernel documentation on virtio, virtqueue details and test examples - https://www.redhat.com/en/blog/virtqueues-and-virtio-ring-how-data-travels Played with existing kernel / user-space USB/IP network implementation - https://github.com/rapido-linux/rapido/commit/9ca2d7a0e27940d59f1eaf7d7e9dc559e77c89ef - https://github.com/rapido-linux/rapido/commit/c4e0cff00bfdaea03b960311266db5f59f7c5390 - wireshark PDU dissection works well For Linux Kernel Library (LKL) / lklfuse plumbing I revisited my walkley project from prior hackweeks, and pushed new WIP branches: https://gitlab.com/ceph-walkley/walkley/-/tree/wip_hackweek_2024 - rebased atop current LKL master - added new walkley-usb binary - added mostly-stubbed virtio-usb host-side driver - started work on guest kernel side virtio-usb driver, reusing as much of usbip/vhci-hcd as possible + TCP tx/rx threads spawned on sysfs/vhci/attach can be swapped out for corresponding virtio transport logic + usbipd user-space component can mostly be avoided, as virtio has better options for device discovery - still quite a bit more work needed to support full USB/IP protocol over virtio-mmio + QEMU / standalone virtio host implementation would likely also be needed, so that mainline inclusion isn't dependent on LKL -
19 days ago by williamleo09 | Reply
This project presents an innovative approach to integrating USB storage with the Linux Kernel Library (LKL). By exploring USB/IP over virtio as an alternative to xHCI emulation, it seeks to simplify USB traffic routing between LKL guests and Linux hosts. The focus on lklfuse USB support demonstrates a commitment to optimizing storage solutions within the Linux ecosystem.
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