I’ve been learning about FreeBSD kernel development, and discovering that, not surprisingly, it’s very, very slow to compile on a Raspberry Pi. So, I decided to figure out how to compile the Pi kernel on a nice fast AMD-64. Firstly, get the kernel sources to a subdirectory under a non-root user profile: mkdir fbsd cd…
How the FDT works In specific, I’m looking at this file bcm2835.dtsi which contains the hardware definitions for the BCM2835, the SOC which powers a Raspberry Pi. Primarily, i’m interested in how to read it. To really make sense of this, you should have this pdf at hand; it’s the hardware manual for BCM2835. If…
It’s been a goal of mine for a while to understand how FreeBSD device drivers work. So, firstly I wrote a simple module; it’s here. The next step is to write the skeleton of a device driver. That is, a device driver that does nothing. The resulting source code is here. The Makefile is very…
In preparation for writing a device driver, I thought I would firstly write a module. The resulting source code is here. Firstly the Makefile: SRCS+=bus_if.h device_if.h examplemodule.c KMOD=examplemodule .include <bsd.kmod.mk> The first line defines the sources. examplemodule.c is my module source. I needed to include bus_if.h and device_if.h since I’m writing my module…
Building a FreeBSD kernel for Beaglebone is not terribly difficult. Firstly, you need the FreeBSD-Current sources: svn co http://svn0.us-east.freebsd.org/base/head /src/FreeBSD/ Next, build the cross-development tools for FreeBSD: cd /src/FreeBSD/head make XDEV=arm XDEV_ARCH=armv6 xdev Then get Crochet-FreeBSD. This is by far the easiest way to build a FreeBSD kernel for Beaglebone git clone git://github.com/kientzle/crochet-freebsd.git Once you…
I recently got a Beaglebone Black. I was very excited; it’s similar to a Pi, but has 60 GPIO ports! Getting a serial console up on it was not quite a simple as I thought, since the BeagleBone uses FTDI. Following the instructions here I installed the OS X serial driver for FTDI. After plugging…
Jasper is the JSP compiler inside Tomcat. For reasons, mainly of curiosity, I wanted to build a Pragmatach plugin which exposes Jasper. Pragmatach supports some template engines such as FreeMarker, ThymeLeaf and Velocity, but I thought Jasper would be a good addition. I chose to use Tomcat 6, mainly because Tomcat 7 uses Servlet 3.0. Pragmatach…
Firstly, here’s the site, and here’s the code. There’s a slideshow, here. Pragmatach is a Java-based web development platform that I wrote, based on ideas from Struts2, Play, JSF2 and Grails. My goals in writing it were: Configuration via annotations. I wanted to be able to fully configure a controller using only annotations and…
When writing custom servlets, it can be quite useful to unit test them. In my case, I used a combination of testng and mockito. The basic idea is simple; mock a HttpServletRequest, and a HttpServletResponse and pass them to the custom servlet. There is a bit more too it, so here’s an example. final HttpServletRequest…
The FDT file for Raspberry Pi, declares UART. I’ve had quite a bit of trouble understanding how declaring a uart in the FDT results in /dev/tty0 and /dev/cuau0 appearing in /dev/ Here are the relevant lines from the FDT: uart0: uart0 { compatible = “broadcom,bcm2835-uart”, “broadcom,bcm2708-uart”, “arm,pl011”, “arm,primecell”; reg = <0x201000 0x1000>; interrupts = <65>;…