Octopus

An end-to-end virtual GPU.

An SR-IOV GPU virtualization stack: a synthetic PCIe device for QEMU and the Linux PF/VF drivers that drive it. Implements the same surface as AMD's MxGPU/GIM stack — PCIe, SR-IOV, BAR partitioning, world-switch scheduling, DMA, IOMMU, VFIO passthrough.

One physical function drives many virtual functions that share the device, the way one octopus brain drives many semi-autonomous arms: the PF time-shares the GPU across VFs through a world-switch scheduler.

Components

• qemu-device/ — the synthetic Octopus PCIe device, built into a QEMU tree
• pf-driver/ — the Linux Physical Function driver, an out-of-tree kernel module
• guest/ — userspace exercisers that drive the device from inside the guest

See DESIGN.md for the architecture and roadmap, and HARDWARE.md for the development substrate.

Scope

Phase	Component	Status
1	QEMU device: BAR0 (MMIO) + BAR2 (scratch RAM), MSI-X, command ring	in progress
2	SR-IOV capability; VF spawn on NumVFs write; VF BAR partitioning	planned
3	PF driver: probe, BAR remap, MSI-X, world-switch scheduler	planned
4	DMA descriptor engine; IOMMU mapping via the streaming DMA API	planned
5	VFIO passthrough into a nested guest; guest VF driver	planned
6	A GEMM workload — the device runs a matmul, not just a memset	planned

Building

PF driver (against the running kernel's headers):

cd pf-driver && make
sudo insmod octopus_pf.ko

QEMU device: drop qemu-device/octopus.c into a QEMU source tree under hw/misc/, add a config OCTOPUS entry to hw/misc/Kconfig, append the source to hw/misc/meson.build, build QEMU, then run with -device octopus.

License

GPL-2.0. The kernel module and QEMU device are GPL-bound by their headers; the rest of the repo follows for consistency. See LICENSE.