Linux kernel: /proc/iomem-like output to kernel log during boot

In order to have something similar to /proc/iomem printed out to the console (and dmesg), this piece of code can be implanted somewhere in the kernel code (in my case it was arch/arm/mach-zynq/common.c). It may be required to add #include headers, depending on the file it’s added to. The original code that produces /proc/iomem is [...]

Linux: How to read through all files (checking a backup)

After finishing a backup to a USB stick, I like to verify that all is in place by reading through all files. Using the “tar” utility with verbose file output seemed to be a good idea. But… Don’t $ tar -cv . > /dev/null For whatever reason, the files aren’t really read. Only the names [...]

Linux Device Tree: What those status = “okay” are about

There are a lot of “okay” assignments in the kernel’s device tree. For example, arch/arm/boot/dts/zynq-zed.dts starts with /dts-v1/; #include “zynq-7000.dtsi” and later on there’s, among others, &sdhci0 { status = “okay”; }; &uart1 { status = “okay”; }; &usb0 { status = “okay”; dr_mode = “host”; usb-phy = <&usb_phy0>; }; Let’s look on the last [...]

bash: Jots on exiting the script

Trapping Call a function (byebye in this case) just before exiting a script: trap byebye exit Or a command: trap ‘echo “Farewell cruel world!”‘ exit It’s possible to catch various signals with “trap” as well. Quit on error In short: Have a set -e at the beginning of the script. It’s a global on-off feature, [...]

overlayroot (and permission issues) on Linux Mint 18.1

Introduction Wanting my media center computer to maintain consistent behavior and be tolerant to sudden power outages, I looked for a way to have the root filesystem read-only. This can cause problems with programs that expect to write to all kind of files allover, and media related software has this tendency to break when things [...]

Wallpaper / desktop background + other stuff on Linux Mint 18.1 / Cinnamon

Desktop wallpaper setting Get the current one: $ gsettings get org.cinnamon.desktop.background picture-uri ‘file:///usr/share/backgrounds/linuxmint/default_background.jpg’ And set it to another: $ gsettings set org.cinnamon.desktop.background picture-uri ‘file:///usr/share/backgrounds/linuxmint/edesigner_linuxmint.png’ Notes: The “file://” prefix is mandatory. There also an org.gnome.desktop.background attribute. Apparently, org.cinnamon.desktop.background overrides the former. For an effect on the screen, the “set” command must be run on the active [...]

Linux / DVB: Playing with command-line utilities

General Yet another collection of jots as I try out stuff. In this post, I’m playing with a Sin Hon DVB dongle, trying but failing to receive terrestrial TV with it. The OS is Linux Mint 18.1. I had also Kodi and Tvheadend installed on the system, but they aren’t discussed here. There’s no coherent [...]

Linux and DVB: Failing with a Sin Hon TDH 601 / HD809 USB dongle

General These are my jots as I attempted to use an DVB USB dongle to receive digital TV in Haifa, Israel. Spoiler: I never managed to get my dongle working properly. Maybe because it was faulty to begin with, and maybe because I missed something. It seems more like the former. It says “HD809″ and [...]

Linux Mint 18.1 + i915: Updating the Intel Graphics stack

Running Linux Mint 18.1 (kernel 4.4.0-53) on a Gigabyte Brix BACE-3160 (with an i915 graphics controller) , I had all kind of minor graphics artifacts (in particular a sluggish mouse pointer and Kodi felt heavy). So obviously, I went for updating the graphics stack. Intel supplies an tool for doing this automagically on a selected [...]

Making a mirror of a WordPress blog on my own computer

This is a note to self on how to create a mirror copy of this blog on my own computer. My own peculiar methods are all over. Create a virtual host on my apache httpd server (port 99) Uncompress the site’s entire public_html directory into the virtual host site’s root directory (that’slazy, I got a [...]