semu is a minimalist RISC-V system emulator capable of running Linux the kernel and corresponding userland. semu implements the following:
- RISC-V instruction set architecture: RV32IMA
- Privilege levels: S and U modes
- Control and status registers (CSR)
- Virtual memory system: RV32 MMU
- UART: 8250/16550
- PLIC (platform-level interrupt controller): 32 interrupts, no priority
- Standard SBI, with the timer extension
My contributions include the virtualization of several hardware components:
- VirtIO Block: Emulates block storage devices, allowing the guest OS to mount and access disk images
- VirtIO GPU: Emulates a graphics device supporting X11, Mesa3D, DirectFB, etc.
- VirtIO Input: Emulates input devices such as mouse and keyboard for interactive use
- VirtIO Entropy: Emulates a random number generator (RNG), supplying entropy required by many software components to operate correctly (e.g., system libraries, cryptographic routines, networking tools)
VirtIO GPU with 3D acceleration through VirGL:
Talk at Open Source Summit North America 2026
Slides of our talk, "Demystifying VirtIO-GPU: Building a Graphics Virtualization Bridge From Scratch", at Open Source Summit North America 2026:
Talk at COSCUP 2026
Slides of my talk, "The Illusion of Hardware: How Modern Virtual Machines Work", at COSCUP 2026: