Document amd64 platform-specific code

kernel/amd64/smp.c

@@ -11,10 +11,14 @@
 #include <sys/debug.h>
 #include <sys/smp.h>
 
+/// Cpu ID counter
 static uint32_t cpu_counter = 0;
+/// Lock for \ref cpu_counter
 static spin_lock_t cpu_counter_lock = SPIN_LOCK_INIT;
+/// The CPUs
 static struct cpu cpus[CPUS_MAX];
 
+/// Allocate a CPU structure
 struct cpu* cpu_make (void) {
   spin_lock (&cpu_counter_lock);
   int id = cpu_counter++;
@@ -36,10 +40,13 @@ struct cpu* cpu_get (uint32_t id) {
   return &cpus[id];
 }
 
+/// Get ID of current running CPU
 uint32_t cpu_id (void) { return (uint32_t)amd64_rdmsr (MSR_GS_BASE); }
 
+/// Assign an ID to the current running CPU
 void cpu_assign (uint32_t id) { amd64_wrmsr (MSR_GS_BASE, (uint64_t)id); }
 
+/// Bootstrap code for non-BSP CPUs
 static void amd64_smp_bootstrap (struct limine_mp_info* mp_info) {
   amd64_load_kernel_cr3 ();
 
@@ -59,6 +66,7 @@ static void amd64_smp_bootstrap (struct limine_mp_info* mp_info) {
     ;
 }
 
+/// Initialize SMP subsystem for AMD64. Start AP CPUs
 void smp_init (void) {
   thiscpu->lapic_ticks = amd64_lapic_init (2500);