Wrote new ISR for AP entry

src/x86/interrupts.h

@@ -2,7 +2,7 @@
 
 #include <stdint.h>
 
-enum exception_code_t
+enum interrupt_code_t
 {
     EXCEPTION_DIV_BY_0 = 0,
     EXCEPTION_DEBUG = 1,
@@ -23,7 +23,9 @@ enum exception_code_t
     EXCEPTION_MACHINE_CHECK = 18,
     EXCEPTION_SIMD_FLOATING_POINT = 19,
     EXCEPTION_VIRTUALIZATION = 20,
-    EXCEPTION_SECURITY = 30
+    EXCEPTION_SECURITY = 30,
+    ISR_AP_START = 127,
+    ISR_SYSCALL = 128
 };
 
 enum isr_type_t

src/x86/isr.c

@@ -24,6 +24,15 @@ void isr_double_fault(void* frame, unsigned int error)
     asm("hlt");
 }
 
+__attribute__ ((interrupt, naked))
+void isr_ap_start(void* frame)
+{
+    asm(".code16");
+    //...
+    asm(".code32");
+    // do something useful
+}
+
 __attribute__ ((interrupt))
 void isr_syscall(void* frame)
 {

src/x86/isr.h

@@ -12,5 +12,8 @@ void isr_page_fault(void* frame, unsigned int error);
 __attribute__ ((interrupt))
 void isr_double_fault(void* frame, unsigned int error);
 
+__attribute__ ((interrupt, naked))
+void isr_ap_start(void* frame);
+
 __attribute__ ((interrupt))
 void isr_syscall(void* frame);