xv6_rpi_port is based on MIT xv6 (http://pdos.csail.mit.edu/6.828/2012/v6.html). It is ported from x86 to armv6 in Raspberry Pi (RPI). The rpi port follows the coding style of xv6 as much as possible to hide the architectural differences between x86 and armv6. The port is not for multiprocessor yet as RPI has only a single processor.
ACKNOWLEDGEMENTS
xv6_rpi_port is inspired by MIT xv6 and Alex Chadwick's Baking Pi Tutorials (http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/). Most architecture-independent code is directly from MIT xv6 though sometimes minor adjustments were done to explicitly initialize data structures. Some C code such as the GPU driver is based on the understanding of Alex Chadwick's assembly code.
Some code for mmu and trap handling is based on the understanding of the Plan 9 bcm port (http://plan9.bell-labs.com/sources/plan9/sys/src/9/bcm/), though the assembly code was completely rewritten. David Welch's RPI code (https://github.com/dwelch67/raspberrypi) is also inspiring for trap handling and uart driver.
If you spot errors or suggest improvements, please send email to Zhiyi Huang (hzy@cs.otago.ac.nz).
Building xv6_rpi_port:
Suppose you have checked out the source with:
$ git clone https://github.com/zhiyihuang/xv6_rpi_port.git
On an RPI installed with Raspbian, type 'make' to make 'kernel.img'.
Copy 'kernel.img' to /boot with a different name:
Comment out the entry 'kernel=kernel_36y.img' and add a new entry 'kernel=kernel-xv6.img' to /boot/config.txt.
Reboot the machine.
Building xv6 user programs and FS (You don't need this step if you don't change the user programs):
cd uprogs make initcode make fs.img
copy 'initcode' and 'fs.img' to the directory 'source'