TL;DR: I followed the graphical installer, opted for the default ZFS/RAID0 and let the installer partition the system drive however it wanted to, and applied these tweaks.
My x220 itself has an i7 CPU, a 512GB SSD, and 16GB RAM. I upgraded the LCD screen to a higher-quality IPS display panel and disconnected the touchpad. I also removed the lid closure sensor, the webcam, and the internal microphone. This negated my need to install drivers or set bootloader options for these devices.
X11
The last step of the installer asked if I’d like to chroot into the new system and apply any post-installation configs. I said yes and proceeded thusly.
I added my login user to the video and wheel groups:
pw groupmod video -m james && pw groupmod wheel -m james
dbus is required for just about anything graphical, so I added this line to /etc/rc.conf:
echo 'dbus_enable="YES"' >> /etc/rc.conf
I also enabled the stock i915kms driver:
echo 'kld_list="i915kms"' >> /etc/rc.conf
Then, I installed the following:
pkg install vim git stow xorg slim openbox firefox \
xf86-input-keyboard xf86-input-mouse
I then set slim to handle graphical login:
echo 'slim_enable="YES"' >> /etc/rc.conf
and start Openbox on login:
echo 'exec openbox-session' >> /home/james/.xinitrc
Permissions
I set permissions for the wheel group to allow the doas command:
echo 'permit persist :wheel' >> /usr/local/etc/doas.conf
Battery
I didn’t go overboard with the kernel tunables, wifi power saving, and so on, keeping the configuration pretty elementary. I get about 5 hours of normal use with the 9-cell battery (which is ~10 years old, at about 95% capacity).
Here’s what I added to /etc/rc.conf:
powerd_enable="YES"
powerd_flags="-a hiadaptive -b adaptive"
performance_cx_lowest="Cmax"
economy_cx_lowest="Cmax"
Other optimizations
These are commented to be self-explanatory. Here’s my /etc/rc.conf:
# Don't hang the boot process while waiting for DHCP
background_dhclient="YES"
# Clear /tmp on boot
clear_tmp_enable="YES"
# Enable Linux compatibility
linux_enable="YES"
And /boot/loader.conf:
autoboot_delay="2"
# More appropriate values for desktop use
kern.maxproc="100000"
kern.ipc.shmseg="1024"
kern.ipc.shmmni="1024"
# Enable the nub and disable the touchpad
hw.psm.trackpoint_support="1"
hw.psm.synaptics_support="0"
# Enable a faster implementation of soreceive
net.inet.tcp.soreceive_stream="1"
# Increase the network interface queue link
net.link.ifqmaxlen="2048"
# Enable hardware accelerated AES
aesni_load="YES"
# Load the H-TCP algorithm
cc_htcp_load="YES"
# Enable CPU firmware updates
cpuctl_load="YES"
# Enable CPU temperature monitoring
coretemp_load="YES"
# Enable LCD backlight control, ThinkPad buttons, etc
acpi_ibm_load="YES"
I don’t usually stream music or watch videos on this computer, so I let Mozilla’s cubeb library handle everything.
Dotfiles
By this point, I could log in to an X session with decent performance, battery life, an editor, a browser, and a way to configure my system.
I use GNU Stow to manage my dotfiles, so the rest was easy:
git clone https://github.com/jamesacklin/dots
cd dots
stow openbox
This installed my window manager theme, made the correct changes to the right-click desktop menu, set my desktop background to light gray, and so on. I repeated the same stow command for the other programs and services I wanted to configure.
Overall impressions
My entire experience was no more complicated than a typical Arch Linux installation. I wasn’t anticipating a “just works” experience like Fedora or Ubuntu, but I was pleasantly surprised to find that my x220 now runs quietly and efficiently while I putter around.
I had previously committed this entire process on the same machine with OpenBSD, but I found that the CPU fan ran audibly. Some quick research online told me that the OpenBSD developers removed something questionable in the fan driver – which is good and in line with their security goals but not great for me.
Thanks to c0ffee.net for almost all of these pointers.