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DOC: small user manual

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boreddevnl
2026-04-14 10:59:52 +02:00
parent fd7fa4f16e
commit bb187faf79
13 changed files with 214 additions and 21 deletions
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28
src/sys/smp.c
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@@ -31,27 +31,24 @@ static inline void wrmsr(uint32_t msr, uint64_t value) {
}
static uint32_t read_lapic_id(void) {
uint32_t eax, ebx, ecx, edx;
asm volatile("cpuid" : "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx) : "a"(1));
return (ebx >> 24) & 0xFF;
extern uint64_t hhdm_offset;
volatile uint32_t *lapic = (volatile uint32_t *)(hhdm_offset + 0xFEE00000ULL);
return (lapic[0x020 / 4] >> 24) & 0xFF;
}
uint32_t smp_this_cpu_id(void) {
if (total_cpus <= 1 || !cpu_states) return 0;
// Use GS-based self-pointer to get the structure first
cpu_state_t *state = NULL;
// Safely check GS:0. If GS is not set or base is 0, this should be handled carefully.
// In BoredOS, if GS is not set, this might still fault depending on address space.
// However, the cpu_states check above covers the most likely early-boot failure.
asm volatile("movq %%gs:0, %0" : "=r"(state) : : "memory");
if (state) return state->cpu_id;
if (!cpu_states || total_cpus == 0) return 0;
uint32_t lapic = read_lapic_id();
if (lapic == bsp_lapic_id) return 0;
cpu_state_t *state = NULL;
asm volatile("movq %%gs:0, %0" : "=r"(state) : : "memory");
if (state && state->lapic_id == lapic) return state->cpu_id;
for (uint32_t i = 0; i < total_cpus; i++) {
if (cpu_states[i].lapic_id == lapic) return i;
if (cpu_states[i].online && cpu_states[i].lapic_id == lapic) return i;
}
return 0; // Fallback to BSP
return 0;
}
uint32_t smp_cpu_count(void) {
@@ -126,7 +123,8 @@ static void ap_entry(struct limine_smp_info *info) {
void smp_init_bsp(void) {
static cpu_state_t bsp_state_static = {0};
bsp_state_static.cpu_id = 0;
bsp_state_static.lapic_id = read_lapic_id();
bsp_lapic_id = read_lapic_id();
bsp_state_static.lapic_id = bsp_lapic_id;
bsp_state_static.self = &bsp_state_static;
bsp_state_static.online = true;