The hardware

CPU

Intel i7-4720HQ: 2.6 GHz (3.6 GHz turbo), 4 cores, 8 threads, 6MB cache

RAM

2x4GB DDR3 1600 MHz (replaced with 2x8GB)

GPU

NVIDIA Optimus dual GPU setup:

• Intel HD 4600, by default using 64MB of system memory as VRAM.
• NVIDIA GeForce 850M, 2GB dedicated VRAM

HDMI and mini-DisplayPort external outputs. By default everything goes through Intel GPU; see below for NVIDIA Optimus support.

Display

15.6" LED-backlit 1080p IPS

Hard drive

Seagate Momentus ST1000LM024: 1TB SATA-II 5400rpm (replaced with Samsung 850 EVO 500GB)

Wired network

Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller; supported by r8169 driver without intervention

Wireless network

Intel 7260; supported by iwlwifi driver without intervention

Touchpad

FocalTech touchpad; see below

Touchscreen

Atmel maXTouch Digitizer; using evdev without intervention

Keyboard

It's a keyboard; see below for details of function keys

Webcam

Generic USB video class (UVC) 720p webcam; works without intervention (tested in camorama)

Audio/microphone

Intel High-Definition Audio; using snd_hda_intel without intervention

LTS Hardware Enablement Stack (HWE)

When using an older Linux distro release on a brand new machine, it's likely that some things won't be very well supported by whichever kernel and Xorg versions that release froze on. Ubuntu's answer to the problem is the LTS Hardware Enablement Stack. At the time of writing, the stack based on 15.04 (Vivid) was the latest, so the following command was used:

sudo apt-get install --install-recommends \
    linux-generic-lts-vivid xserver-xorg-core-lts-vivid xserver-xorg-lts-vivid \
    xserver-xorg-video-all-lts-vivid xserver-xorg-input-all-lts-vivid \
    libwayland-egl1-mesa-lts-vivid

The only problem with this is that some packages might not be able to build drivers against the new kernel. I found this to be the case for VirtualBox, but using the latest version available from the VirtualBox site gets around this.

Suspend

I decided to try out suspend and resume early on, since historically it's been a fairly quirky area of hardware support. In this case, the nouveau driver barfed into the logs and prevented sleep. Blacklisting it seems to fix the problem: add blacklist nouveau to /etc/modprobe.d/blacklist-nouveau.conf. This was no big deal, since I'm either using the Intel GPU or the proprietary NVIDIA drivers.

Graphics driver

Like a lot of decent modern laptops, this one has a dual-GPU setup: the Intel HD 4600 as part of the CPU, and an NVIDIA 850M.

As is to be expected, the Intel GPU just works. The HWE upgrade enabled DisplayPort 1.2 Multi-Stream Transport (MST) support, which allowed me to daisy-chain my Dell U2515H monitors which support this feature. (Note: the monitors ship with this feature disabled, you need to enable it in the OSD on each monitor.)

The NVIDIA GPU was less straightforward: at the time of installing, the latest NVIDIA drivers in the Ubuntu 14.04 repos would not build against the 3.19 kernel from 15.04. Luckily, the backported newer drivers were added within a couple of weeks.

There are two ways to enable NVIDIA support on a laptop like this: using "Bumblebee" to allow per-application use of the NVIDIA GPU, or using "NVIDIA Prime" to switch the entire desktop environment between GPUs (requires logging out and back in again). Because I don't intend to make much use of the NVIDIA GPU, I opted for the latter:

sudo apt-get install nvidia-346-updates nvidia-prime

By default the Intel GPU should remain selected. The GPU can be switched from the nvidia-settings control panel.

Touchpad driver

The laptop has a FocalTech touchpad, which I hadn't heard of before, and which isn't handled properly even in the 3.19 kernel from Ubuntu 15.04. Luckily, these touchpads seem to be used in multiple Asus laptops now, and Ask Ubuntu had an answer: Asus X750JA and Ubuntu Gnome 14.04. Following those instructions and rebooting, the touchpad had gained two-finger vertical scrolling, edge scrolling, and also the ability to use synclient to tweak the settings.

In terms of customising the touchpad behaviour, I put the following in my ~/.xprofile:

synclient HorizTwoFingerScroll=1 \
          VertEdgeScroll=0 \
          TapButton3=2 \
          PalmDetect=1

• Enable 2-finger scrolling horizontally (vertical 2-finger scroll is enabled by default)
• Disable vertical edge scrolling, since I'm just going to be using 2-finger scrolling all the time
• Turn 3-finger taps into a "middle button" click (2-finger taps are "right click" by default)
• Enable palm detection, to try and get rid of spurious inputs when typing

Keyboard

It's a keyboard. It generally works as well as you'd expect for one of the oldest standard bits of computer hardware. What tends to vary these days is of course the special/"fn" keys on the keyboard. This one has several. Going left-to-right, top-to-bottom:

Sleep key

Is recognised by power management functionality: if you have it set to suspend when the sleep button is pressed, pressing this key will suspend the same as via any other route.

Wireless toggle

Not registered at all; see below for fix.

Decrease/increase display brightness

Not registered at all; see below for fix.

Toggle display

Seems to switch the laptop screen off and on, not sure where this is handled.

Select display mode

This key is horrible. Really really horrible. So horrible it needs its own subsection (see below). Needless to say, it doesn't work properly.

Toggle touchpad

Recognised as XF86TouchpadToggle, but nothing actually uses it.

Mute/increase/decrease volume

Recognised and behave as expected.

Box with an "S" in it?

Recognised as XF86Launch1.

Camera

Recognised as XF86WebCam.

Running person?

Recognised as XF86Launch6.

Stop/prev/play-pause/next

Recognised as XF86AudioStop, XF86AudioPrev, XF86AudioPlay and XF86AudioNext.

Calculator

Launches calculator.

Final words

The laptop makes a pretty adequate desktop replacement, and all of the hardware should be well-supported by an up-to-date Linux distro. However, for those that opt for a long-term stable releases, I hope documenting the quirks I encountered will help somebody in a similar situation.