Architecture
Boot
Boot path from Limine to userland
SlopOS boots as a Limine payload under OVMF. The ISO builder injects the chosen framebuffer resolution and optional kernel command line into the boot configuration.
Stages
| Stage | Responsibility |
|---|---|
| Limine handoff | Read bootloader requests, memory map, framebuffer, and modules |
| Early CPU setup | Bring up serial logging, descriptor tables, syscall entry, and service tables |
| Memory handoff | Initialize physical frames, heap, paging, and kernel mappings |
| Interrupt setup | Install exception and IRQ entry, LAPIC, IOAPIC, vectors, and exception stacks |
| SMP | Bring up application processors and per-CPU state |
| Platform devices | Discover ACPI tables, HPET, PCI, interrupt routing, VirtIO, and input devices |
| Scheduler and init | Start scheduling, launch init, and enter userland |
Boot invariants
- HPET is required for the supported QEMU runtime.
- LAPIC timer calibration is required. HPET is the preferred reference clock.
- The scheduler tick uses the LAPIC timer. PIT is only a legacy calibration fallback and does not drive scheduling.
- Application processors start their LAPIC timers after calibration is available.
- VirtIO devices use modern interrupt delivery; legacy mode is not the supported runtime path.
Command line
The justfile threads boot and test command-line keys into the ISO:
BOOT_CMDLINE='tests=off roulette=skip boot.debug=on' just boot-log
TEST_CMDLINE='tests=on tests.run=slopos_mm::*' just testCommon keys:
| Key | Meaning |
|---|---|
tests=on/off | Enable the test harness |
tests.shutdown=on/off | Exit QEMU through the debug-exit device after tests |
tests.verbosity=quiet/summary/verbose | Test output detail |
tests.run=glob | Run matching tests |
tests.skip=glob | Skip matching tests |
roulette=skip | Bypass the Wheel of Fate |
boot.debug=on | Enable extra boot logging |