This is a simple exercise designed to get you started on seL4 and set up your hardware kit. It contains very detailed instructions, together with the existing source code and the seL4 manual you should have no problem doing it.
Your Environment
If you haven't already you may want to take a look at Odroid C2 Lab, which provides details on the contents of your kit. Log into the CSE lab machine before you plug in the hardware, as this triggers the machine to run specific scripts for your project to work, on your account. If you have permission/tftp issues down the line, try unplugging/replugging the usb/serial adapter and ethernet adapter while logged in.
The required tools can be set up on a CSE lab machine by running
9242
, as follows:
weill% 9242 newclass starting new subshell for class COMP9242... weill% aarch64-linux-gnu-ld aarch64-linux-gnu-ld: no input files
The above updates your path to include the cross compilers and other
tools located in the cs9242 home directory, and python packages that
the seL4 build depends on for your local user account. You will
need to run 9242
each time you start a new shell on a lab
machine in order to build the project successfully.
Get the source
The sources to the project are also available at https://github.com/SEL4PROJ/AOS-manifest
for anybody outside UNSW who wishes to take a look at the project.
Using the projects from this repository will require the use of the
repo tool.
Read the README.md
for more details on setting up the project from that repository.
Clone your copy of the milestone 0 starting code.
We use git
for revision control for this project, and it
will be simplest if you do also. You will be submitting via a provided
git repository for each milestone in the project. You will need to
support yourself if you use any other tools.
You can find some pointers on using git
on our git page.
git clone https://gitlab.cse.unsw.edu.au/COMP9242/21T2/{your-zID}-m0.git aos-2021-m0
You will need to provide your username and password when cloning. If you set up your ssh-keys on our gitlab server you can use the following command instead:
git clone gitlab@gitlab.cse.unsw.edu.au:COMP9242/21T2/{your-zID}-m0.git aos-2021-m0
Note: you will only be using this repository for milestone 0. Once you have selected your group members for the remainder of semester you will be using a different group respository to submit.
Building SOS
Dependencies
The CSE lab machines and login servers have already been configured with all dependencies. To set up another machine, follow the seL4 build dependencies (you only need to install the Base Build Dependencies and the Python Dependencies) instructions on the seL4 docsite. Note: that you only require the aarch64 cross-compilers.
Once this stage is completed successfully, you should be able to compile the AOS project.
Build the project
We use Cmake and ninja as our build system, which you can read more about on the seL4 docsite. Importantly, this build system does not build in the source tree: you create another directory (in this case build to build code in, and develop in the source directories.
Follow these instructions to build SOS:
cd aos-2021-m0 # change to the project directory
mkdir build # create a build directory
cd build # change to the build directory
../init-build.sh # initialise the build directory
ninja # init-build
By default ninja builds in parallel. If you have a lot of build errors, this can cause confusing output. use ninja -j1 to build with only one thread, which will make the build slower but also serialise the output.
Getting it Going
Booting your Odroid-C2 for the first time is easy:
- From a CSE lab machine run 9242 odroid tty
-
Reset the ODroid-C2 by running 9242 odroid reset in a different terminal.
The first time you run this you may be prompted to enter your zID and zPass.
--- UART initialized after reboot --- [Reset cause: unknown] [Image: unknown, amlogic_v1.1.3046-00db630-dirty 2016-08-31 09:24:14 tao.zeng@droid04] bl30: check_permit, count is 1 bl30: check_permit: ok! chipid: ef Load bl33 from eMMC, src: 0x00034200, des: 0x01000000, size: 0x00074ae0 be ad de d f0 ad ba ef be ad de not ES chip [0.275944 Inits done] secure task start! high task start! low task start! NOTICE: BL3-1: v1.0(debug):4d2e34d NOTICE: BL3-1: Built : 17:08:35, Oct 29 2015 INFO: BL3-1: Initializing runtime services INFO: BL3-1: Preparing for EL3 exit to normal world INFO: BL3-1: Next image address = 0x1000000 INFO: BL3-1: Next image spsr = 0x3c9 U-Boot 2015.01 (Sep 26 2017 - 00:56:33) DRAM: 2 GiB Relocation Offset is: 76f31000 ------------------------------------------------- * Welcome to Hardkernel's ODROID-C2 ------------------------------------------------- CPU : AMLogic S905 S/N : HKC213254DFFB152 MAC : 00:1e:06:35:fd:d2 BID : HKC2211804 ------------------------------------------------- register usb cfg[1][0] = 0000000077f95190 register usb cfg[0][1] = 0000000077f951b0 vpu detect type: 5 vpu clk_level = 7 set vpu clk: 666667000Hz, readback: 666660000Hz(0x300) MMC: aml_priv->desc_buf = 0x0000000073f29d30 aml_priv->desc_buf = 0x0000000073f2bec0 SDIO Port C: 0, SDIO Port B: 1 [mmc_init] mmc init success In: serial Out: serial Err: serial ---------------------------------- MMC Size : 8 GB ---------------------------------- reading boot-logo.bmp.gz ** Unable to read file boot-logo.bmp.gz ** reading boot-logo.bmp ** Unable to read file boot-logo.bmp ** movi: the partiton 'logo' is reading... MMC read: dev # 0, block # 61024, count 2048 ... 2048 blocks read: OK hpd_state=1 [CANVAS]addr=0x3f800000 width=3840, height=1440 set hdmitx VIC = 16 hdmitx phy setting done set hdmitx VIC = 16 hdmitx phy setting done Error: Bad gzipped data There is no valid bmp file at the given address Net: Meson_Ethernet Hit [Enter] key twice to stop autoboot: 0
Development cycle
We have developed a few tools to speed the development cycle along. The makefile can copy the sos operating system, known as a bootimage to your tftp directory and reset the OdroidC2. Below is a typical development cycle, assuming the path changes to your login script:
- In a terminal on a CSE machine, run 9242 odroid tty.
- In another terminal on a CSE machine, run 9242 odroid serial.
- Make your changes in the source directory, (hint: learn cscope).
- Build with ninja, in the build dir.
- Test your changes (from the build dir ../reset.sh).
- Repeat from step 3 above until satisfied, or you fall over for lack of sleep.
The Milestone
The example skeleton operating system includes an application
tty_test
which starts up, prints out its name, and then
blocks itself forever.
The example includes a printf
implementation that outputs
data to seL4's debug console. In fact it uses the seL4 debug API
seL4_DebugPutChar
. This function should only be used for
internal SOS debugging, not as a console for applications, so, your task is to modify the sos_write
function to send data through the operating system and across the
network to your netcat(nc
) console.
The second part of milestone zero is to find a partner for the rest of the project. The project is to be completed, in pairs, unless prior permission has been obtained from the LiC.
Before you complete this milestone, be sure to spend time becoming familiar with the seL4 Debugging Guide. It will save you a lot of debugging effort throughout the project.
Recommended procedure
-
Read (and understand) the code in
projects/aos/sos/src/main.c
and the code in theprojects/aos/apps/tty_test
application directory. - Read the documentation on libserial.
-
Initialise libserial during SOS startup. Note that you need to initialise libserial
after
network_init
is called. - Design a simple IPC protocol to transfer data from the user program to your operating system (Recommended reading: seL4 Reference Manual, Chapter 4 (all) and Chapter 10 (Section 10.1, 10.2, 10.2.2.1, 10.3.1.9,). Note that an endpoint has already been set up between the tty_test application and sos.)
-
Write the client side implementation in
sos_write
. -
Change the
syscall_loop
inmain.c
to recognise your new protocol, and print out a debug message when you receive one of these messages. -
Edit
tty_test.c
so that it tests yoursos_write
function. - Change the server side so that it now prints the data to libserial, which will send it onto the network.
-
Test that all of
tty_test
's output now goes to the netcat console, not the console debugger.
Assessment
Milestone submission
See the milestone submission guidelines for instructions on submitting your milestone solution.
Milestone Demonstration
You will need to demonstrate user applications printing to the 2nd console via libserial, running on the OdroidC2 hardware to the tutor during the demonstration period. You should be prepared to show your tutor which files you modified in your solution, and explain any design decisions you made.
Note that since you do not have consistent virtual memory management yet, your protocol will be fairly simple for now. However, it should be upgraded as more parts of the system are completed. Your tutor will be particularly interested in the details of your IPC interface with different sized blocks of data etc, and how you plan to improve it in future.
Hint: sending a byte at a time is not a good solution.
You will let the tutor know who your partner is so that group accounts can be created for you.