* [fat] long entry support

* [fat] getdents

* [bin] add ls

* [bin] migrate to vnx

* [bin] add userspace lib

* [fs] add getdents syscall

* [sys] impl syscall about ls

* [init] support compiling initcode

* [init] use execve instead of exec in initcode

[syscall] migrate to linux-like syscall

#8 resolved
#9 resolved

* [mm] lazy alloc

* [mm] uvmfree for lazy

* [mm] uvmcopy for lazy alloc

* [mm] uvmalloc for lazy

* [mm] lazy alloc and CoW