Linux on Miek Gieben

Go and Alpine Linux

Sat, 06 Jun 2015 11:13:00 +0000

Alpine Linux is the small Linux OS everybody is using for Docker images. It is super small and has a sh*tload of packages. It’s libc is musl libc, which is different than glibc most other Linux distros are using. When deploying Go on such a image you want a truly static binary.

Building a static binary can be done with the following command (this is for SkyDNS):

% go build -ldflags "-linkmode external -extldflags -static"
# github.com/miekg/skydns
/var/tmp/go-link-FI6Ox0/000000.o: In function `_cgo_632c88804cec_C2func_getaddrinfo':
/home/miek/upstream/go/src/net/cgo_unix.go:55: warning: Using 'getaddrinfo' in
statically linked applications requires at runtime the shared libraries from the
glibc version used for linking

That ugly warning is because glibc uses nss(5) “Nameserver Service Switch” which uses dlopen(3) to dynamically load the correct resolver library. The end result is that the Go binary can’t resolve any DNS records!

Pi cluster fun

Sun, 15 Feb 2015 16:21:00 +0000

I’ve bought 3 Raspberry Pis (B+, a week before the announcement of the Pi 2), and created a little cluster with them. Each Pi is connected to wireless (192.168.1.0/24) and they share an internal, wired, 10.248.0.0/16 network.

Virtual IP

I want one IP address to be load balanced across the three Pis. This can be with the CLUSTERIP target in iptables. In raspbian the kernel module for this was not enabled, but luckily this was fixed very quickly.

xmodmap is dead

Tue, 28 Oct 2014 20:18:00 +0000

I’m using an Apple keyboard at work since a day or two, but for some reason this keyboard has a special key for eject, because in 1898 that was useful when you wanted to eject a cdrom.

Anyway making this key do something useful proved incredible painful, especially since xmodmap is deprecated and we should all use xkb (setxkbmap andxkbcomp). In our new world of hotplugging everything this kinda makes sense (xmodmap settings are lost when your USB keyboard goes to sleep).

Short kernel compile howto for Debian/Ubuntu

Tue, 10 Sep 2013 08:18:00 +0000

Download the kernel’s source from http://kernel.org;
Unpack it somewhere (will use ~/src/linux-3.11 here);

Copy the config from the distribution over;

 cp /boot/config-3.8.0.30-generic ~/src/linux-3.11/.config

Apply any patches;
Go to the kernel source and create an up to date config.
```
 make oldconfig
```
Just use the defaults for all the questions you’ll get;
Compile the kernel into a debian package for easy installation and removal.
```
 fakeroot make-kpkg --initrd -j 8 --revision 3.11custom kernel_image
```
Install the resulting .deb file and reboot.

Macbook Air (6,1) 2013 model with Ubuntu

Sat, 31 Aug 2013 11:48:00 +0000

Assorted notes, not a step-by-step HOWTO!

How to get Ubuntu Raring (13.04) up and running on your shining new MacbookAir. Note some things are not working (yet). This is with 3.11:

audio (speakers don’t work, plugged in headset does work), however see this latest patch;
webcam (see http://mactaris.blogspot.co.uk/2013/07/webcam-settings-20-will-support.html for a list of changes, it is not a UVC device anymore);
after a resume the screen brightness only knows on/off.

Expectation for 3.12 (when released), everything is working, except:

Make GNOME3 usable

Mon, 03 Jun 2013 18:50:00 +0000

GNOME3 in the default install is unusable, not as bad as Unity, but bad. Luckily with some ~~minor~~ tweaking it can be made to work quite nicely.

These are some assorted notes on how I got stuff working the way I like.

From a fresh Ubuntu install, install GNOME3:

sudo apt-get install gnome-desktop-environment

Then:

Normal focus mode:

 gsettings set org.gnome.desktop.wm.preferences focus-mode 'sloppy'
 gsettings set org.gnome.desktop.wm.preferences auto-raise false

Extensions: