feat(mm): initial mm work

src/ex/init.zig

@@ -2,9 +2,10 @@ const std = @import("std");
 const b = @import("base");
 const pl = b.pl;
 const ke = b.ke;
+const mm = b.mm;
 
 pub fn init(boot_info: *pl.BootInfo) void {
-    _ = boot_info;
+    mm.init(boot_info);
 
     pl.late_init();
     ke.sched.late_init();