It was time for a new work laptop so I got a Dell XPS 15 9950. I wasn't planning to write a blog post of how to install Debian 8 "Jessie" on the laptop but since it wasn't just install and use, I will share what is needed to get the wifi and graphics card to work.
So first download the DVD-1 AMD64 image of Debian 8 from your favorite download mirror. The closest one for me is the Hong Kong mirror. You do not need to download the other DVDs, just the first one is sufficient. The netinstaller and CD images will not provide a good experience since they need a working network/internet connection. With the DVD image you can do a full default desktop install and most things will just work out-of-the-box.
Now you can do a regular install, no special procedure or anything will be needed. Depending on your desktop selection it will boot right into lovely GNOME3.
You will quickly notice that the wifi is not working out-of-the-box though. It is a Qualcomm Atheros QCA6174 and the Linux kernel version 3.16 shipped with Debian 8 does not support that wifi card. This card needs the ath10k_pci kernel module which is included in a newer Linux kernel package from the Debian backports archive. If you don't have the Dell docking station as neither I do, then there is no wired ethernet that you can use for getting a temporary Internet connection. So use a different computer with Internet access to download the following packages from the Debian backports archive manually and put them on a USB disk.
After that connect the USB disk to the new Dell laptop and mount the disk using the GNOME3 file browser (nautilus). It will mount the USB disk to /media/$your_username/$volume_name. Become root using sudo or su. Then install all downloaded package from USB with like this:
cd /media/$your_username/$volume_name dpkg -i linux-base_*.deb dpkg -i linux-image-4.7.0-0.bpo.1-amd64_*.deb dpkg -i firmware-atheros_*.deb dpkg -i firmware-misc-nonfree_*.deb dpkg -i xserver-xorg-video-intel_*.deb
That's it. If dpkg finished without error message then you can reboot and your wifi and graphics card should just work! After reboot you can verify the wifi card is recognized by running "/sbin/iwconfig" and see if wlan0 shows up.
Have fun with your Dell XPS and Debian!
PS: if this does not work for you, leave a comment or write to meebey at meebey . net