Lenovo Thinkpad X250


I scored this one on "eBay Kleinanzeigen" (think of it as the German craigslist) for a decent price (considering the good configuration and overall condition). While searching for one to buy i observed some quirkiness in the pricing of these machines:
  • those with 8GB of RAM usually cost less more than those with 4Gb than the upgrade would cost
  • the ones with i7 processor cost a lot more than those with i5, but offer only a mildly better performance
  • the IPS panel (especially the FHD one) raised the price by more than a spare part panel on eBay cost
  • the better the specs, the more a good condition increased the price
  • a classic hard drive lowered the price only a little bit compared to a SSD

Well, i finally found one with the best i5, 8GB of RAM, TN panel and 256GB SSD in fairly good condition for a good enough price. It had a swedish keyboard layout and no LTE option.
In the following month i bought the docking station, bigger battery, FHD IPS panel and LTE option whenever i found one for a good price. It took a while, but it was a good bit cheaper than buying one with similar specs in one go.
I also bought a bigger SSD, but i needed the smaller one for another machine anyway. When i find a keyboard with UK layout i will replace that too, but for now i go with stickers.

System

  • Lenovo ThinkPad X250, 2015 12.5" Ultrabook, 1420g-1580g
    • BIOS Boot / UEFI Boot # Switching the OS with UEFI needs two attempts to work ?.?
    • ACPI events , ACPI keys # Although it has only a few ACPI keys
    • S2R , S2D # S2D suspends, but freezes on resume (4.9.34-gentoo)
    • power consumption 4.4-5.4W # 1/6 brightness FHD IPS panel, WiFi, very light use (as low as 3.6W with the HD TN panel)
    • 23Wh internal, 23Wh or 72Wh external # Both are changeable, although the internal needs the case to be opened
  • Intel Core i5-5300U SOC (2.3GHz, 15W TDP, vPro) # Alternatives: i3, i5 sans vPro and i7 (all 5th gen)
    • cpufreq # Via pstates
  • Intel Broadwell-U PCH-LP (Premium)
    • m.2 ?, SATA , M.2 + SATA ? # Three M.2 slots (or two plus smartcard reader)
    • Gigabit Ethernet
    • USB 3.1 # 2 Ports
    • Headset connector # Sound is nice, very little interference
    • Microphone / Speakers # Speakers sound thin but not too distorted and are quite loud, the mic is quite good
    • Fan control ? # A bit whiny under high load, very quiet otherwise
    • One DDR3L-1600 slot, up to 8GB # Low voltage modules needed!
  • Intel HD Graphics 5500 # 979 points in 3DMark 11 GPU, on par with the GeForce GT 550M (upper mid-range in 2011)
    • Acceleration: GUI , Video , 3D , OpenCL ?
    • Brightness control
    • MiniDP / VGA ?
  • 12.5" matte FHD IPS # Nice colors, good black level, could be brighter. Alternatives: HD TN (quite ok for a TN) or HD IPS (never seen)
  • Intel Dual Band Wireless-AC 7265 (802.11a/b/g/n/ac + Bluetooth 4.0) # Not all 7265 support ac, and some are even single band
    • WiFi / bluetooth / kill switch
  • Ericsson N5321 (GSM/GPRS/EDGE/HSPA+, GPS) # Alternative: Sierra Wireless EM7345, supposedly no as well supported under linux
    • LTE / GPS ?
  • SD card reader
  • Webcam 720p
  • Smartcard reader: ? # could read some cards, but could not write to the blanks i bought. Probably the wrong kind of card, though
  • Docking Port


RAM


The X250 has only one RAM Slot which (according to $file thinkwiki and the other $file thinkwiki) officially only supports up to 8GB Modules. Anyway, Lenovo actually sells a 16GB module which lists the X250 as $file supported. It works fine for me. Some other Modules are reported $file to $file work too.

Dock


Lenovo sticks to native (non-USB-connected) docks for the X, T and W models, sharing the same port for all models from the *40 generation until at least the *60 generation. Three types are available, "Basic", "Pro" and "Ultra". Common among all three:
  • VGA
  • 3 USB 2.0 ports (one always on)
  • Gigabit Ethernet
  • Combo Audio Port ($file CTIA pinout)
  • Lock, Kensington
  • New style rectangular power connector

They differ only in the amount of USB 3.0 and digital video ports:
  • ThinkPad Basic Dock untested
    • 1 USB 3.0 port
  • ThinkPad Pro Dock
    • 3 USB 3.0 ports
    • DVI-D , DisplayPort
  • ThinkPad Ultra Dock untested
    • 3 USB 3.0
    • DVI-D, 2 DisplayPort, HDMI (two of which can be active, $file ThinkWiki states trouble with Linux)

I have the Pro model, which works fine. The other models will probably work just as well, apart from the Ultra's troublesome MST hub.

Quirks


The Device performs very well. But it has some drawbacks. Most are minor issues:
  • The rubbery coating is rather delicate and gets scuff mark from just about everything
  • There is some flexing in the upper right of the lower body when moving the screen up and down
  • The battery is held by to clips, which can easily pulled back and then one only has to uses the third hand to pull out the battery
  • Only 2 USB Ports, no HDMI (but VGA and mini DP)
  • Suspend to ram can result in freezes if suspend/resume cycle come in quick succession


UEFI boot


Works, but is a bit annoying: whenever i select a boot option via F12, it simply reboots and i have to select it again. Then it works.

Input Devices


The Keyboard has a sub-par layout:
  • The F-Keys share their function with special keys, thus F1 is Mute (and Fn-F1 is F1)
    • Fn-Esc is Fn-Lock, then F1 is F1 and Fn-F1 is mute
      • Can be set as default in the BIOS, works fine for me
      • Does only affect the F-keys, not the keypad
  • Suspend and hibernate buttons are missing
    • Most of the special keys send normal keycodes (from the XF86... range)
    • The few that send ACPI events are probably already in use by most people
    • I use F12, which ist marke by three small squares. Whatever ?.?

The Touchpad is a bit iffy too:
  • It lacks real buttons, the thing as a whole can be clicked on the lower part, leading usually to cursor movement while clicking. Insufferable.
    • Setting AreaBottomEdge to around 9000 (either via synclient or xorg.conf.d) disables the lower few mm of the touchpad. Now the "buttons" can be used quite ok.


X "Freezes"


Under certain circumstance (its not too clear which) some (again, its not really clear who is this "some") people have random (sometimes very rare, sometimes often) freezes in X. In some cases the driver is just restarted (either working then or freezing again), in other the System keeps freezed.
In my case, for example, i had no freezes at all until i changed my kernel configuration by activating the EFI framebuffer handover (the kernel uses simplefb which in turn uses the EFI-initialized framebuffer) to get a seamless and boot process without any flicker due to mode changes. After that, i started to get freezes, sometimes after a few seconds, sometimes never (or not before i shut down anyway).
There are some things said to help:
  • Use UXA acceleration instead of SNA
  • Disable acceleration altogether (obviously bad, try only as a very last resort)
  • Disable IOMMU (quite bad when using virtualisation, try to avoid)
  • Disable DMA Remapping (fancy IOMMU stuff)
  • Disable EFI Framebuffer (or Framebuffer handover and simplefb)

Obviously, the later helped in my case. But disabling DMA remapping helped too, so i could get seamless boot without freezes. I compile my own kernel, so i changed my kernel config. I marked the config that works for me, but ymmw. In addition, kernel command line parameters can be used too (although i don't know them)
The Framebuffer Handover is found here:
  • Bus Options (PCI etc)
    • $file Mark VGA/VBE/EFI FB as generic system framebuffer

The simplefb Framebuffer here:
  • Device Drivers
    • Graphics Support
      • Build drivers only as module
      • Framebuffer Devices
        • Build framebuffer devices only as module
        • $file Simple framebuffer support

The DMA remapping here:
  • Device Driver
    • $file IOMMU Hardware Support
      • $file Support for Intel IOMMU using DMA Remapping Devices
      • $file Enable Intel DMA Remapping Devices by default

Here is a Ticket
https://bugs.freedesktop.org/show_bug.cgi?id=89360#add_comment

Verdict


Build quality is ok. Not as sturdy as older Thinkpads. It lacks the clamshell design, the rubbery coating is quite delicate, some flexing. On the other hand: its light and slim. The dual battery is nice. The keyboard has a nice feel, but the layout has its quirks. And its a chicklet design. The touchpad lacks real keys (but the trackpoint has some).
Linux runs mostly fine. The issues with X are common for the chipset, not this device in particular and can (in my experience) be avoided.

total: 181.65ms (include: 2.55, request: 22.55, trace: 0.52, init: 3.29, load: 0.01, parse: 149.01, menu: 1.11, template: 2.45, minify: 0.16)