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+xv6_rpi2_port is based on MIT xv6 (http://pdos.csail.mit.edu/6.828/2012/v6.html).
+It is ported from x86 to armv6 and then to armv7 in Raspberry Pi (RPI2/3). 
+The rpi port follows the coding style of xv6 as much as possible to hide the architectural
+differences between x86 and armv6/armv7. The port is not for multiprocessor yet
+though RPI2/3 has four cores.
+
+ACKNOWLEDGEMENTS
+
+xv6_rpi2_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.
+
+Mahdi Amiri Kordestany (mahdi@cs.otago.ac.nz) ported xv6 from RPI1 to
+RPI2/3.
+
+If you spot errors or suggest improvements, please send email to
+Zhiyi Huang (hzy@cs.otago.ac.nz).
+
+Building xv6_rpi2_port:
+
+Suppose you have checked out the source with:
+
+$ git clone https://github.com/zhiyihuang/xv6_rpi2_port.git
+
+On an RPI2/3 installed with Raspbian, type 'make loader' to make 'kernel7.img'.
+
+Copy 'kernel7.img' to /boot with a different name:
+# cp kernel7.img /boot/kernel-xv6.img
+
+Comment out the old entry 'kernel=' and add a new entry
+'kernel=kernel-xv6.img' to /boot/config.txt.
+
+Add the following into /boot/config.txt:
+
+kernel_old=1
+disable_commandline_tags=1
+enable_uart=1
+
+
+Reboot the machine.
+
+The USB keyboard is not working yet. The only way to input into
+the console is to use the mini UART (serial port). You can use a 
+USB to TTL Serial Cable to connect the mini UART to a virtual terminal.
+You may use minicom or CoolTerm to create the virtual terminal.
+You have to open the lid to connect the cable to the GPIO pins (14 and 15) 
+of the Pi. 
+
+Building xv6 user programs and FS (You don't need this step if you
+don't change the user programs):
+
+cd uprogs
+make 
+
+copy 'initcode' and 'fs.img' to the directory 'source'
+