Replace the state-relabel-only round-robin with the SUB-OS "Weave"
scheduler backed by a genuine callee-saved context switch. Threads now
actually run on their own kernel stacks instead of merely having their
state field rewritten.
What was implemented:
- sub_ctx_switch(): per-arch assembly (arch/x86_64/cpu/switch.asm,
arch/aarch64/cpu/switch.S, arch/armv8i/cpu/switch.S) that saves/restores
the callee-saved register set (+ flags on x86_64) on each thread's own
stack, plus a first-run trampoline (sub_thread_trampoline) that launches
a freshly forged thread frame with entry/arg in callee-saved registers.
- task_forge_frame(): builds the initial saved-context frame per arch so
the very first switch into a new thread lands on the trampoline; task_t
gains a pointer-sized ctx_sp so the same struct works on 64- and 32-bit.
- Weave policy (kernel/sched.c): WEAVE_NLANES priority lanes, always
dispatch the lowest non-empty lane round-robin; a task that yields
voluntarily is woven UP a lane (interactive), one preempted after
burning its quantum is woven DOWN (CPU-bound). Cooperative switching
(sched_yield / task_exit) is always live; timer-driven preemption is
gated behind sched_set_preempt() and left disarmed for now.
- task_exit() now switches to the next runnable thread via
sched_exit_current() instead of spinning/halting.
- Boot-time weave_selftest() (x86_64) and sched_dump() diagnostics.
How it was verified:
- Builds clean for all three targets: x86_64 (CROSS_COMPILE=x86_64-linux-gnu-,
RUSTC="rustc --target x86_64-unknown-none"), aarch64, armv8i. No new
warnings; the new x86_64 asm carries a .note.GNU-stack section.
- Booted x86_64 under QEMU (TCG): the self-test runs three cooperative
kernel threads to completion on separate stacks with the expected
1->2->3 round-robin interleave, reports "20 real context switches,
3/3 workers exited", returns cleanly to the boot thread, and boot
proceeds normally to ring-3 init and the shell. No fault/panic.
Left unverified:
- The aarch64/armv8i sub_ctx_switch frames build and link but are not yet
boot-tested on their QEMU targets (tracked in docs/AUTODEV_ROADMAP.md).
- Timer preemption path is implemented but disarmed; exited kernel threads
currently leak their stack (reaper is next in the backlog).
Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Jk6K69yGS7zYgvoWd6nJxQ
bochs_vbe_init switches the adapter into graphics mode at boot step [5/14], and
from that point the VGA text buffer is no longer scanned out. This kernel boots
to a TTY, so every message after that -- and the whole shell session -- was
invisible in the emulator window and reached only the serial line.
The console now moves to the framebuffer at that transition, which also makes
the nano editor render correctly: it positions with tty_set_cursor() rather than
escape sequences, and the TTY driver dispatches that to fbcon.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
Three build-correctness fixes plus README coverage of the new kernel core.
The Makefile had no header dependency tracking, so editing a header left every
unrebuilt caller linked against the old layout. That is how the desktop's
window paint callbacks silently landed at the wrong struct offset after
gui_window_t grew: gui_apps.o was never recompiled. Compiles now emit .d files
via -MMD -MP and the build pulls them in.
The include has to sit at the end of the file with .DEFAULT_GOAL pinned to
`all` -- a .d file's first rule would otherwise become make's default goal and
turn a bare `make` into a silent no-op.
drivers/video/canvas.c carried the same font table defect gui_gfx.c did: the
`// \` comment on the backslash glyph continues onto the next line, swallowing
the `]` entry and shifting every glyph from ']' onward by one, so all lowercase
text rendered one letter off.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
- Implement Intel 82574L / 82567LM / I217 / I219 PCIe Gigabit NIC driver with DMA ring buffers and auto-negotiation in drivers/net/e1000e.c and include/drivers/e1000e.h
- Implement VirtIO-GPU 2D hardware graphics display adapter driver with dirty rect flushing in drivers/virtio/virtio_gpu.c and include/drivers/virtio_gpu.h
- Implement Dynamic CPU Frequency Scaling and ACPI CPPC Power Governor with performance, powersave, ondemand, conservative, and schedutil policies in drivers/power/cpufreq.c and include/drivers/cpufreq.h
- Implement VirtIO-Input para-virtualized tablet/mouse event driver in drivers/virtio/virtio_input.c and include/drivers/virtio_input.h
- Expand stage2 kernel bootloader loading boundary to 768 KB (1536 sectors)
- Add LazyBox applets: 'cpufreq', 'gpuinfo', 'e1000e'
- Verified across x86_64, AArch64, and ARMv8i targets
- Add dedicated Linux-compatible Tree visualizer with UTF-8/ASCII branch tracking, -L depth filtering, human sizes, and permissions in userland/lazybox/tree.c
- Implement Hardware Invariant Timestamp Counter (TSC) calibration and microsecond delay timer in kernel/tsc.c and include/kernel/tsc.h
- Add Virtual Terminal color palette, live resource utilization bars, and logo banner in kernel/vt_art.c and include/kernel/vt_art.h
- Add LazyBox applets: 'tree', 'tscinfo', and 'vtart'
- Update README.md documentation and command matrix
- Implement modern freestanding C++17 containers (Vector<T>, UniquePtr<T>, String) in kernel/cpp/cpp_containers.hpp
- Implement object-oriented Device driver model (Device, BlockDevice, CharDevice, VirtualRamDiskDevice, VirtualNullDevice, VirtualZeroDevice, DeviceManager) in kernel/cpp/cpp_device.hpp and kernel/cpp/cpp_device.cpp
- Add C++ kernel performance microbenchmark suite in kernel/cpp/cpp_bench.cpp
- Export C-FFI bridges and add cross-architecture fallbacks in kernel/cpp/cpp_fallback.c and include/kernel/cpp_kernel.h
- Add LazyBox applets: 'cppdevs' and 'cppbench'
- Update README.md documentation and command matrix
- Add memory-safe ELF-64/32 binary header and program header inspector in rust/src/kernel/elf.rs
- Implement Buddy allocator and external memory fragmentation analyzer in rust/src/mm/buddy_analyzer.rs
- Add RFC-8439 Poly1305 128-bit message authenticator and ChaCha20-Poly1305 AEAD in rust/src/crypto/poly1305.rs and rust/src/crypto/chacha20poly1305.rs
- Export C-FFI bridges and add cross-architecture fallbacks in rust/rust_fallback.c and include/kernel/rust.h
- Add LazyBox applets: 'readelf', 'buddyinfo', and 'aead'
- Update README.md documentation and command matrix
- Implement flicker-free atomic double-buffered frame rendering and sub-tick input polling in userland/lazybox/snake.c
- Add multi-input support (PS/2 keyboard scancodes and serial ANSI arrow escape sequences)
- Add sound effects (food beep, game over chime) and live speed scaling (+/- keys, P to pause)
- Add POSIX /dev/shm shared memory subsystem in ipc/shm_posix.c and include/ipc/shm_posix.h
- Add DNS resolver cache with TTL tracking in net/ipv4/dns_cache.c and include/net/dns_cache.h
- Add audio tone and jingle synthesizer in sound/beep.c and include/sound/beep.h
- Add %o octal formatting support in lib/vsprintf.c
- Add LazyBox applets: 'shm', 'dnscache', and 'beep'
Claude