add 'preparing virtual kernel filesystem' section

We then compile and install dpkg as the first part of our final system, and use dpkg along with some clever dependency hacking to satisfy all remaining dependencies needed to install apt. This allows us to rely on apt for the overwhelming majority of tasks involving the installation of software onto our new system, and to allow us to avoid the exercise in tedium that is manual dependency management.

##Preparing the virtual kernel filesystem mount points

First we create the directories which are supposed to contain virtual kernel filesystems. These are filesystems which are located in memory only and created dynamically every time the kernel is loaded. 

Each kind has a different purpose. The `devpts` contains device files for each pseudo terminal on your system. The `proc` contains information about every single process. The `sysfs` contains driver and device information. The `tmpfs` is a freely usable space which programs may use to store information in memory. 

Since we have not built our kernel yet, we are forced to use the ones existing on our host system by mounting them in the appropriate locations in our target system. When our system is fully built, the new kernel will automatically mount these filesystems in their appropriate places.

```

mkdir -pv $LFS/{dev,proc,sys,run}

mknod -m 600 $LFS/dev/console c 5 1

mknod -m 666 $LFS/dev/null c 1 3

mount -v --bind /dev $LFS/dev

mount -vt devpts devpts $LFS/dev/pts -o gid=5,mode=620

mount -vt proc proc $LFS/proc

mount -vt sysfs sysfs $LFS/sys

mount -vt tmpfs tmpfs $LFS/run

if [ -h $LFS/dev/shm ]; then

  mkdir -pv $LFS/$(readlink $LFS/dev/shm)

fi

```

### Entering our chroot environment

We must now, as the `root` user on our host system, enter our base environment by changing our root directory into the final system's root directory, and use the temporary environment we've previously constructed to build our final system. Use the following command after you have become `root` on your host: