User/kernel copying:
-5 Too many copies of user/kernel copying code
- -10 Doesn't check for page boundaries
- -3 Imperfect checking for page boundaries
+ -20 Doesn't check for page boundaries
+ -10 Imperfect checking for page boundaries
-5 Doesn't check whether pointers are at or above PHYS_BASE
-2 Imperfect checking whether pointers are at or above PHYS_BASE
+3 Copies large chunks while properly observing page boundaries