I recently upgraded from Fedora 13, to the new Fedora 14 release. Despite keeping my old "/home" directory, there was a lot of reinstalling and tweaking that I had to go through. With my laptop I make use of battery charging thresholds, which are good for preserving the longevity of your battery life, and stop it being prematurely depleted. The way battery charging thresholds work, are that they inhibit charging when the AC adaptor is connected, until the battery level is above and below a certain percentage. I tend to use the levels, 20% and 80%, so that the battery doesn’t begin charging until the battery level is below 20%, and when this occurs it stops charging at 80% of the total battery capacity; as I have mentioned, this prevents unnecessary wear to the battery. It is especially useful if your laptop is generally always connected to the AC adaptor, apart from the odd rare occasion. Because then you can set the battery to stay at a safe, 40% or so, which would keep it from being worn down, despite being installed in the laptop, with the AC adaptor attached.

Battery charging thresholds are a rather advanced feature, and it’s not in-built into the Linux kernel, so far as I know. There is however a kernel module for Thinkpads called tp_smapi. This module provides an interface for advanced features, such as battery charging thresholds, among other things. Now I will move on to explaining how to install the tp_smapi kernel module.

You can build tp_smapi from source, in which case here’s the link to some more detailed instructions and steps to follow on ThinkWiki. However, I find that this still does require a modecombe of concious effort on my part to keep tp_smapi up to date and working with my current kernel version (which gets updated a lot more frequently than tp_smapi itself.) So, the solution is to use a prepackaged kernel module, that can automatically rebuild itself. This is called an akmod or automatic kernel module. Thankfully, somebody smarter than me has already built just such a package for use with Fedora. You can download it from here, you’re looking for the package titled akmod-tp_smapi-0.40-1.fc11.i686.rpm.

So I’m presuming that you’ve downloaded it to your “/home/YourUsernameHere/Downloads” directory, in which case we need to open a terminal and switch to that directory:

cd /Downloads

The next step is to install the akmod. Probably the best way to do this is a local install with YUM. You need to be root in order to install this program, so use “sudo” if you’ve set it up, if not you can use “su -c” which I have used below (so you can quickly copy and paste it):

su -c 'yum localinstall akmod-tp_smapi-0.40-1.fc11.i686.rpm --nogpgcheck'

Now read the on screen instructions to confirm that it has installed okay.

Before tp_smapi will work you need to reboot your computer. Instead of watching the pretty Fedora startup screen (the silhouette of the Fedora logo slowly filling up with white), press the Escape key on your keyboard, to show the log of what’s happening on boot. You’ll see an entry for tp_smapi, being built. If it’s successful you’ll see a green “[Ok]” next to the entry. If not, you’ll also be warned at boot time, with an orange caution-triangle, showing boot time errors, before and after you log in.

So now, hopefully it has built successfully and should work. However, you have to manually load the new kernel module. To do this, again, become root user and execute the following command in a terminal:

su -c 'modprobe tp_smapi'

To verify this has worked I then (still as root user, and you have to explicitly type “su” and the root password) execute a command to show me the battery charging thresholds, as follows:

cat /sys/devices/platform/smapi/BAT0/*_charge_thresh

This should display two numbers, on above the other, in the terminal. The first, and top one is the thresholds to start charging at, the one below it, the last one, is the level at which the battery stops charging. It may be a good idea, to note down the above command, as it’s quite useful if you want to remember how to use these battery charging thresholds.

The final part of setting up the akmod_tp-smapi is to make sure that it is loaded _automatically_ for you, at boot time, so you don’t have to execute “modprobe tp_smapi” yourself, manually, every time you reboot. To do this, you need to be root, and execute the following command:

echo modprobe tp_smapi > /etc/rc.d/rc.local

Now if you reboot your laptop and then try the command to show you the battery charging thresholds, as root (cat /sys/devices/platform/smapi/BAT0/*_charge_thresh), it should just work for you.

A final point to note are the two commands below (you, again, must switch to root with “su“):

echo 20 > /sys/devices/platform/smapi/BAT0/start_charge_thresh

echo 80 > /sys/devices/platform/smapi/BAT0/stop_charge_thresh

As I have mentioned before, these are the two battery charging thresholds that I use. The top one, as the end of the command suggests, is the start threshold, and the second is the stop charging threshold. Execute these commands, with your own numbers after “echo“, and it’ll set those values for you. If you put the two commands on to one line, and separate them with a semi-colon, like so:

echo 20 > /sys/devices/platform/smapi/BAT0/start_charge_thresh; echo 80 > /sys/devices/platform/smapi/BAT0/stop_charge_thresh

Then it will execute the two commands at the same time, to avoid having to copy and paste twice. Remember, use the following command to check the charging levels:

cat /sys/devices/platform/smapi/BAT0/*_charge_thresh

I was a bit concerned when moving from the wholly IBM made T41p to the Lenovo manufactured T61 there was a difference, and that is worrying when holding a very much loved brand in its hands. The T61 made a number of compromises from the old ‘p’ performance model. Going from a 4:3 aspect ratio and screen resolution of 1400×1050, to a widescreen 16:10 and resolution of 1280×800 is a big change, you lose that vertical screen real-estate and greater resolution in general but on the upside the newer LCD was brighter.

Moving to the T400, I again noticed a considerable improvement in the brightness of the LCD display and at this point had become used to the more restricted resolution, if anything it saved my eyes.

Another thing about the older Thinkpads were they used to get very hot, probably contributed to by the performance discrete-graphics which were lacking in my T61. The T400 on the other hand has ‘switchable graphics’, both integrated and discrete graphics chipsets that can be selected in the BIOS as well as at runtime if there is OS support (no there is currently no Linux support for this). What struck me was that the T400 was even cooler than the T61 despite having both graphics chipsets inside it. This can be attributed to the refinement in processor production, moving to smaller manufacturing processes means a smaller thermal output, this coupled with an improvement in fan and cooling technology — is visible if you look at the heatsinks behind the fan grilles, they’re now copper and not aluminum — there were also improvements made to the design to make them more efficient. I should note that under Linux the laptop is cooler in most situations than under Windows, at least for the integrated graphics. I talk at length about these things because they’re noticeable factors and are quite important if you use a machine day in day out.

A smaller difference is the improvement in weight and size which although slight is noticeable and much welcomed.

Of course with increased specifications there is increased power but what makes this even more amazing is that the power is so much greater and yet the heat and weight are the same if not lower. Moving up to an Intel Core2 Duo instead of just the Intel Core does make a difference, perhaps the faster DDR3 RAM also plays a part in this; now that I have upgraded my RAM to 4GB I find using swap space almost a thing of the past.

I would always recommend getting a desktop-speed, that is 7200RPM, hard disk drive as this is the bottleneck in most systems I just swapped over my T61′s HDD, only having to remove one screw to gain access to it (it is placed on a caddy with shock absorbers).

These details bring me to another strength of Thinkpads in general customisability and support. One cannot argue with a three-year on site warranty, that’s next day support including parts and labour, brilliant. With the help of ThinkWiki and the Thinkpads.com forum as a guide, one has enough information to maintain this system for a long time. Thinkpads are built to facilitate easy access and modularity, they publish a hardware specification called the Hardware Maintenance Manual (HMM) (link for the T400 HMM) that shows you step-by-step, with exploded view diagrams for help, how to assemble and disassemble your individual Thinkpad model. Things that would normally be a chore to replace if they went wrong on other manufacturers laptops, like disc drives, are simple as they are modularised in the form of the UltraBay, a removable disc drive. The HDD as I have mentioned is also on an easy access and removal caddy and the RAM is not very hard at all to replace. What’s more many of these more minor things such as replacing the RAM do not void your warranty and if something goes wrong, sometimes Lenovo will merely send out the part, so well documented and easy is the process of disassembly, it’s a real ‘feature’ for me.

The keyboard remains one of the chief components that bring people to the Thinkpad line, it is world renowned and still holds up well to this reputation. If you go into a laptop shop, just press down firmly on the keys in the middle of the keyboard, watch it bend and flex, sometimes quite a lot. Thinkpads don’t really suffer from this and typing on the T400 is a joy. Night typing is helped with the continued presence of the ThinkLight, an LED that lights up the keyboard to an extent (Fn+Page Up).

The speakers are no longer located on the base, facing downwards towards the user but are on the sides of the keyboard, they’re noticeably louder than in previous models, especially than the T41p.

Battery life is very good, much improved over the T61 generation despite only possessing a 4-cell battery, using the Windows-only Lenovo BatteryStretch technology I could get 4 hours of battery time, running under reduced conditions however. There are 4, 6 and 9-cell batteries available which again, is not something you see from all manufacturers. Indeed people regularly report reaching over 8 hours on Windows using the 9-cell battery. In Linux equally battery life is good from a hardware perspective, but also I believe there’s been software improvements as it is easy to get the laptop down to around 10W usage which I found very hard to do on older models, this will easily get you 3 hours of battery life at half screen-brightness using the same 4-cell battery,

A brief note regarding Linux support, like most Thinkpads the T400 is well supported on Linux, it’s all documented on the ThinkWiki where you’ll also find user installation notes. There are a couple of things that still as of today do not work perfectly. The audio although working becomes very quiet when adjusted towards the middle of the slider and below and the mute key is not registered by the on-screen display but does mute, as it works in hardware not software [Update: I have found out that this is supposedly fixed in Kernel 2.6.33 and has to do with the BIOS having an ALSA driver, it should now mute at boot and display an OSD]. As I have noted above switchable graphics cannot be fully utilised, switched, at runtime as there is no support in the drivers and may never be, hopefully in a later revision of this technology. The Intel 5300AGN wireless chipset is supported out of the box, within the kernel, and provides a very good range and quality link. The keyboard’s function-key combinations and special keys do work, such as the ThinkLight and even the ones located on the Function keys are supported in large part by ibm-acpi, a kernel package. Integrated graphics provided by Intel work out of the box and work reasonably well, apart from some 3D games where there appears to be some driver peculiarities that cause graphical glitches, the discrete ATI HD3470 is just picking up basic open source 3D support now.

There are a few let-downs when it comes to the T400, not all of them Lenovo’s fault. It would’ve been nice to have a digital video-out in the form of DisplayPort or DVI (which is available on the dock), this was achieved in the thinner and lighter X300 so there was no real reason for the omission here. The only other thing really missing for future-proofness would be USB3 as this already has 802.11n wireless built-in, however that is not Lenovo’s fault and isn’t supported in the chipset.

In conclusion, the Thinkpad T400 is a very well balanced laptop in terms of performance versus weight. It is very powerful and not only uses the latest processor which supports x86-64 as well as advanced virtualisation capabilities but also has a very practical and usable switchable graphics chipset that can provide battery life gains or accelerated graphical power for games or work, when needed; the implementation really is very good falling back to the reliable BIOS switch if there is no OS support, as on Linux. The machine is so powerful in fact that working on this laptop is indeed a step up from my not-too-old desktop computer. I can run games such as Team Fortress 2 and all the productivity software I can shake a fist at, the only issue is really storage, my model only came with an 80GB 5400RPM disk drive but I swapped it out for a 200GB 7200RPM drive, and with greater than 500GB 7200RPM notebook HDDs coming out this isn’t an insurmountable problem. The T400 is more powerful than any of my friends’ machines and yet I got it for cheaper, with the possibility of a longer life in terms of the warranty and the better documentation, spare parts and community support. It has really enabled me to move to this as my sole computer and that is testament, there is not much I cannot do on it.

I hope this hasn’t been a too wishy-washy review, it’s more a general impression to my specific use case than a side-by-side comparison to its competitors. In essence it’s just a great machine, the best Thinkpad I have used so far.