kernel: string.h, gdt, msr, cpu and ist

kernel-src/arch/x86-64/main.c

@@ -1,7 +1,12 @@
 #include <arch/e9.h>
 #include <logging.h>
+#include <arch/cpu.h>
+
+static cpu_t bsp_cpu;
 
 void kernel_entry() {
+	cpu_set(&bsp_cpu);
 	logging_sethook(arch_e9_putc);
+	arch_gdt_reload();
 	__assert(!"kernel entry end");
 }