- Fix swapped command IDs: attach_backing was 0x0104 (FLUSH),
resource_flush was 0x0106 (ATTACH_BACKING). Now correct.
- Increase process stack from 4 pages (16 KB) to 16 pages (64 KB)
to prevent stack overflow in display process.
- Restructure display-qemu to avoid MockFramebuffer's 32 KB array
inflating the VirtIO path's stack frame.
- Wire snake app to render through display server via IPC instead
of UART escape codes. Uses existing renderer.rs pixel renderer.
- Init now delegates display endpoint to snake process.
Tests:
- IPC tests: spawn thread B explicitly (CreateProcess no longer
spawns threads since the boot logic fix)
- Memory tests: RequestPages now returns Value(va) not Slot(cap)
- MockPlatform: tracks VA→PA mappings for translate_va
- ReleasePages test: ignored (RequestPages no longer creates
regions — ReleasePages needs redesign)
CapSlot::const_new(value):
- const fn that panics at compile time for invalid values
- Replaces CapSlot::new(N).unwrap() in init, echo, snake
- Cap slot constants are now compile-time verified
Also fixes handle_release_pages to use translate_va instead of
treating VA as PA directly.
35 kernel tests pass, 1 ignored.
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.
Complete microkernel boot pipeline: adapter loads only init + storage + display
from disk. Init bootstraps all other servers by reading binaries from the
storage server via IPC, parsing ELF, creating processes, mapping pages, and
spawning threads.
New syscalls:
- CreateEndpoint: userspace endpoint creation with full capability grant
- DebugPutchar: debug output to UART from userspace
- MapPage: cross-process page mapping (init loads binaries into children)
- SpawnThreadIn: spawn thread in another process via capability
Key fixes:
- Per-process L1 page tables for VPN[2]=0 (prevents cross-process corruption)
- Separate kernel_pt from page_tables[0] (init pid=0 overwrote kernel PT ref)
- Thread Running state set in switch_to_next (syscalls rejected without it)
- Pending IPC results applied during context switch
- SIE disabled during boot (timer can't preempt into unready processes)
- User heap VA starts at 0x40000 (avoids shared buffer at 0x30000)
- RequestPages maps at user VAs via per-process heap allocator
VirtIO GPU:
- Adapter probes for GPU device, initializes resource/scanout/backing
- Display server writes to mapped framebuffer, flushes via GPU virtqueue
- 640x480 BGRA framebuffer with transfer-to-host and resource-flush
Storage server:
- Userspace VirtIO block driver using pre-mapped MMIO and DMA pages
- FAT16 filesystem reader serving file-read requests via IPC
- Shared buffer protocol: init writes filename, storage writes file data
Echo app for IPC testing (adapter-loaded echo proved the pipeline end-to-end).
- CreateProcess only creates process + grants cap, no thread spawning
- boot::boot takes &mut BootResult instead of returning it (fixes -> ! sret convention issue)
- Init creates 6 server processes, sets up supervisor, enters receive loop
- No faults on QEMU with full boot sequence
- Userspace linker script: apps/servers link at 0x10000 (user VA)
- Adapter linker script: kernel links at 0x80200000 (S-mode)
- Each uses build.rs to emit its own -T flag, global config only sets panic=abort
- ELF loader: page-aligns segment mappings, handles non-aligned vaddrs
- Stack: 4 pages (16K) mapped below program
- SP set to top of stack (0x10000), not bottom
- FAT16 disk image forced (mformat was creating FAT32)
- End-to-end verified: VirtIO → FAT16 → ELF → userspace → ecall → exit
Every server now has lib.rs (testable) + main.rs (deployable binary).
Binary is 3 lines: extern crate userspace_rt + call run().
Hardware servers use feature flags for adapter selection.
9 RISC-V binaries ready for the disk image.
- Halt syscall: only pid 0 (init) can halt, adapter uses SBI SRST
- Fault notification: kernel delivers fault info to process fault handler endpoint before killing
- Supervisor: tracks restart counts, back-off up to 5 restarts
- Shutdown: notifies servers, waits with timeout, calls halt
- Trap handler: faults now call kernel.handle_fault instead of halting
