SMP and timer interrupts

kernel/amd64/debug.c

@@ -3,11 +3,14 @@
 #include <libk/printf.h>
 #include <libk/std.h>
 #include <libk/string.h>
+#include <sync/spin_lock.h>
 #include <sys/debug.h>
 
 #define PORT_COM1   0x03F8
 #define BUFFER_SIZE 1024
 
+spin_lock_t serial_lock = SPIN_LOCK_INIT;
+
 static bool amd64_debug_serial_tx_empty (void) {
   return (bool)(amd64_io_inb (PORT_COM1 + 5) & 0x20);
 }
@@ -30,10 +33,15 @@ void debugprintf (const char* fmt, ...) {
   buffer[sizeof (buffer) - 1] = '\0';
 
   const char* p = buffer;
+
+  spin_lock (&serial_lock);
+
   while (*p) {
     amd64_debug_serial_write (*p);
     p++;
   }
+
+  spin_unlock (&serial_lock);
 }
 
 void amd64_debug_init (void) {