Implemented a simple kernel heap

kernel/include/kmalloc.h

@@ -0,0 +1,25 @@
+#ifndef _KALLOC_H
+#define _KALLOC_H
+
+#include <kernel.h>
+
+// TODO: Set a better minimum that just a random number
+#define KMALLOC_MIN_PAGES 4
+
+// kmalloc() singly-linked list node
+struct kmalloc_node {
+	size_t size;
+	int free;
+	struct kmalloc_node* next;
+};
+
+extern struct kmalloc_node* kmalloc_head;
+
+int   kmalloc_init(void);
+void* kmalloc(size_t size);
+void* kzalloc(size_t size);
+void* kcalloc(size_t size, size_t count);
+void* krealloc(size_t size, void* ptr);
+void  kfree(void* ptr);
+
+#endif