black screen when trying to boot windows 8.1

[Grille-Pain]

Hi,

I'm trying to run windows 8.1 from my Linux (Linux Mint). The windows is on a raw partition, so I didn't create any virtual partition, I used this command:
sudo VBoxManage internalcommands createrawvmdk -filename win8 -rawdisk /dev/sda4

Now, when I start windows from virtual box, I have a black screen, and nothing else =(

Here is a copy paste of my logs (somehow the forum doesn't allow me to post the link directly...):
http://pastebin.com/raw/Z8ji16GK

Thanks!

[Martin]

A partition is not a disk.

You can attach the log here directly by using the "Upload attachment" function below the text entry box.

[Perryg]

http://www.virtualbox.org/manual/ch09.html#rawdisk

Be sure to read all warnings and see what "-relative" does.