Cleaning up and commenting

src/kernel/boot/boot.S

@@ -54,17 +54,24 @@ _start:
   mov ds, eax
   mov es, eax
 
+  //; Jump to kernel address space
   movabs rax, offset upper_memory
   jmp rax
 
   upper_memory:
 
+  //; Move stack pointer to kernel space
   mov rax, KERNEL_OFFSET
   add rsp, rax
 
+  //; Remove identity mapping
   mov rax, 0
   movabs [BootP4], rax
 
+  //; Jump to kmain()
 .extern kmain
   movabs rax, offset kmain
-  jmp rax
+  call rax
+
+  hlt
+  jmp $

src/kernel/boot/kmain.c

@@ -2,14 +2,14 @@
 
 void clear_screen()
 {
-  unsigned char *vidmem = (void *)(0xB8000 + KERNEL_OFFSET);
+  unsigned char *vidmem = P2V(0xB8000);
   for(int i=0; i < 80*24*2; i++)
     *vidmem++ = 0;
 }
 
 void print_string(char *str)
 {
-  unsigned char *vidmem = (void *)(0xB8000 + KERNEL_OFFSET);
+  unsigned char *vidmem = P2V(0xB8000);
   while(*str)
   {
     *vidmem++ = *str++;