Snake renders using ANSI escape codes via debug_putchar syscall,
bypassing the VirtIO GPU (which has a QEMU 11.x legacy MMIO bug
where transfer_to_host_2d succeeds but doesn't transfer data).
Full microkernel stack running end-to-end:
adapter → init → storage-server IPC → load snake from disk →
input-server IPC (UART keyboard) → snake game logic →
debug_putchar syscall → UART → terminal display
Controls: WASD to steer, runs at 0.2s tick rate.
Green O=head, o=body, red @=food, #=border.
Every syscall stub now uses proper types from types/ — CapSlot,
EntryPoint, StackPointer, VirtualAddress, PageCount, ProcessId,
PermissionSet, Ticks. The compiler prevents swapping entry/stack,
passing a ProcessId where a CapSlot is expected, or using an
address as a page count.
New display types in types/display.rs:
- Color(u32) with rgb() constructor
- ScreenCoord(u16) for x/y positions
- Dimension(u16) for width/height
Updated throughout:
- userspace/syscall.rs: all params typed, returns Option instead
of sentinel usize::MAX
- server-framework: endpoint param is CapSlot
- port-framebuffer: trait uses Color, ScreenCoord, Dimension
- hw-virtio: DmaAddrs uses PhysicalAddress/VirtualAddress,
GPU commands use Dimension
- All servers, drivers, bins, apps updated for new signatures
- permission-manager: process field uses ProcessId
- PermissionSet: added bits() accessor
89 tests pass, full QEMU boot verified.
Separate abstractions from implementations following DIP:
servers/ drivers/
│ │
▼ ▼
ports/ (trait-only crates, zero deps)
New crates:
ports/ (abstractions):
- port-framebuffer: Framebuffer trait
- port-block-device: BlockDevice trait + SectorId
- port-input-device: InputDevice trait + InputEvent types
drivers/ (implementations depend on ports/):
- driver-framebuffer-virtio: VirtIO GPU framebuffer
- driver-framebuffer-mock: test double
- driver-block-virtio: VirtIO block device
bins/ (composition roots wire server + driver):
- display-qemu: DisplayServer<VirtioFramebuffer>
- storage-qemu: storage server with VirtIO block
Servers no longer own their hardware traits or driver code.
Neither server nor driver depends on the other — both point
inward to the port abstraction.
