Implement PCD (page cache disable) paging bit

include/map.h

@@ -4,6 +4,7 @@
 #define MAP_PRESENT (1 << 0)
 #define MAP_RW      (1 << 1)
 #define MAP_USER    (1 << 2)
+#define MAP_NOCACHE (1 << 3)
 #define MAP_FLAGS   (MAP_PRESENT | MAP_USER)
 
 #endif // _MAP_H

kernel/amd64/mm.c

@@ -14,6 +14,7 @@
 #define AMD64_PG_PRESENT (1 << 0)
 #define AMD64_PG_RW      (1 << 1)
 #define AMD64_PG_USER    (1 << 2)
+#define AMD64_PG_PCD     (1 << 4)
 #define AMD64_PG_HUGE    (1 << 7)
 
 /* Auxilary struct for page directory walking */
@@ -97,6 +98,7 @@ static uint64_t mm_resolve_flags (uint32_t generic) {
   flags |= ((generic & MM_PG_PRESENT) ? AMD64_PG_PRESENT : 0);
   flags |= ((generic & MM_PG_RW) ? AMD64_PG_RW : 0);
   flags |= ((generic & MM_PG_USER) ? AMD64_PG_USER : 0);
+  flags |= ((generic & MM_PG_NOCACHE ? AMD64_PG_PCD : 0));
 
   return flags;
 }

kernel/sys/mm.h

@@ -11,6 +11,7 @@
 #define MM_PG_PRESENT (1 << 0)
 #define MM_PG_RW      (1 << 1)
 #define MM_PG_USER    (1 << 2)
+#define MM_PG_NOCACHE (1 << 3)
 
 uintptr_t mm_alloc_user_pd_phys (void);