kernel: add header files

arch/x86_64/include/kernel/machine/init.h

@@ -0,0 +1,28 @@
+#ifndef KERNEL_X86_64_INIT_H_
+#define KERNEL_X86_64_INIT_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define __X2(x) #x
+#define __X(x)  __X2(x)
+
+#define __define_initcall(fn, id)                                              \
+	static initcall_t __initcall_##fn##id __used __section(                \
+		".initcall" __X(id) ".init")                                   \
+		= (fn)
+
+extern int ml_init(uintptr_t arg);
+
+extern const struct framebuffer_varinfo *bootfb_varinfo(void);
+extern const struct framebuffer_fixedinfo *bootfb_fixedinfo(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif