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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
/*
* LumeOS Kernel Main Entry — Global Initialization Sequence
*
* All CPUs enter kernel_main() after the assembly bootstrap (entry.S)
* has enabled MMU, cleared BSS, and called early_cpp_init().
*
* BSP (cpu_id == 0) executes the full subsystem initialization DAG.
* APs spin on ap_boot_sync, then perform per-CPU init only.
*
* Reference: docs/specs/global_init.md
*/
#include <lume/types.h>
#include <lume/atomic.h>
#include <lume/panic.h>
#include <lume/fdt.h>
#include <lume/pmm.h>
#include <lume/console.h>
#include <arch/cpu.h>
// ============================================================
// Forward declarations for subsystem init functions.
// Each is implemented by its owning module. On failure they
// call kernel_panic() directly — no error return.
// ============================================================
// BSP global init (strict order)
void console_init(); // 1. UART ready; kprintf/panic can output
void fdt_init(uint64 fdt_paddr); // 2. Parse FDT, build device node table
void pmm_init(); // 3. Buddy allocator ready
void slab_init(); // 4. kmem_cache ready; operator new usable
void vmm_init(); // 5. Fine-grained kernel page table; retire early_pgdir
void trap_init(); // 6. Set trap vector, register IRQ dispatcher
void plic_init(); // 7. Configure PLIC (threshold, priority, enable)
void timer_init(); // 8. Configure timer interrupt (scheduler tick)
void sched_init(); // 9. Create BSP Idle Task, init ready queues
// Boot self-test runner
void selftest_run_all();
// AP per-CPU init
void vmm_init_ap(); // Switch to BSP-built kernel page table
void trap_init_ap(); // Set this CPU's trap vector
void plic_init_ap(); // Enable this CPU's PLIC context
void timer_init_ap(); // Start this CPU's timer interrupt
void sched_init_ap(); // Init per-CPU ready queue, create Idle Task
// ============================================================
// Second-stage synchronization barrier (C++ layer)
// AP cores spin here until BSP finishes all global init.
// ============================================================
static lume::atomic<uint32> ap_boot_sync;
// Early UART output functions, defined in lib/panic.cc
// They are safe to use before console_init().
extern "C" void early_putc(char c);
extern "C" void early_puts(const char* s);
// ============================================================
// kernel_main — C++ entry point for all CPUs
// ============================================================
extern "C" [[noreturn]] void kernel_main(uint64 cpu_id, uint64 fdt_paddr) {
if (cpu_id == 0) {
// ========================================================
// BSP: Absolute single-core period — no locks needed.
// APs are spinning on ap_boot_sync.
// ========================================================
// Early console setup: discover UART via FDT before ANY output.
console_early_init(fdt_paddr);
early_puts("\n\n");
early_puts("====================================\n");
early_puts(" LumeOS Kernel v0.1\n");
early_puts("====================================\n");
early_puts("[boot] BSP online, cpu_id=0\n");
early_puts("[boot] Higher-half kernel active\n");
// --- Subsystem init DAG (strict top-down order) ---
// 2. FDT parsing
fdt_init(fdt_paddr);
early_puts("[init] fdt_init done\n");
// 3. Physical memory manager (Buddy)
pmm_init();
early_puts("[init] pmm_init done\n");
// 4. Slab allocator — operator new usable after this
slab_init();
early_puts("[init] slab_init done\n");
// 4.5. FDT Phase 2 — build DeviceNode object tree (needs Slab)
fdt_unflatten();
early_puts("[init] fdt_unflatten done\n");
// 5. Virtual memory manager — retire early_pgdir
vmm_init();
// 5.5 Drivers MMIO mapping Registration
// MUST BE CALLED IMMEDIATELY AFTER vmm_init! Otherwise UART is lost.
console_init();
early_puts("[init] vmm_init & console mapped\n");
// 6. Trap handler — set trap vector
// trap_init();
early_puts("[init] trap_init (stub)\n");
// 7. PLIC interrupt controller
plic_init();
early_puts("[init] plic_init done (mapped)\n");
// 8. Timer interrupt (scheduler tick source)
// timer_init();
early_puts("[init] timer_init (stub)\n");
// 9. Scheduler — create Idle Task 0, init ready queues
// sched_init();
early_puts("[init] sched_init (stub)\n");
// 10. Boot self-tests — verify subsystem correctness
selftest_run_all();
early_puts("[boot] BSP init complete, releasing APs\n");
// Release APs with RELEASE semantics:
// guarantees all global data is visible to APs.
ap_boot_sync.store(1, __ATOMIC_RELEASE);
// BSP enables interrupts — first timer tick will preempt
// into the scheduler loop.
// arch::cpu::intr_on();
early_puts("[boot] BSP entering idle loop\n");
} else {
// ========================================================
// AP: spin until BSP finishes global init
// ========================================================
while (ap_boot_sync.load(__ATOMIC_ACQUIRE) == 0)
;
// --- Per-CPU init only (no global data mutation) ---
// vmm_init_ap();
// trap_init_ap();
// plic_init_ap();
// timer_init_ap();
// sched_init_ap();
// AP enables interrupts — becomes Idle Task on this CPU
// arch::cpu::intr_on();
}
// All CPUs: idle loop (wfi until interrupt)
while (true) {
arch::cpu::halt_until_interrupt();
}
}
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