uCore+

You have found uCore+, a highly experimental operating system intended for Operating System Course in Tsinghua University.

Compile & Run

System requirements

uCore+ supports a lot of different architectures, including x86, amd64, ARM and MIPS.

Compiling uCore+ requires you having a (cross) compiler installed for the a specific architecture. For most linux distributions, multilib gcc (supporting x86 and amd64), and arm-none-eabi-gcc have builtin packages. You may need to compile a mips-sde-elf-gcc yourself. It is suggested to use the exact architecture tuple recommanded here.

There are some other packages you need to install (below is there package name in Ubuntu):

ncurses-dev : used to build uCore+ build configuration tools.
qemu : Provide the virtualized environment to run uCore+. Note that to use QEMU binaries for ARM and MIPS, extra packages needs to be installed manually for some linux distributions.
u-boot-tools : providing the mkimage command, used to create u-boot image for ARM uCore+.

Quick Try

Run the following commands in your terminal to get uCore+ AMD64 running on QEMU.

download or clone uCore+ source code
cd ucore
make ARCH=amd64 defconfig
make
make sfsimg
./uCore_run

Build with buildroot image

With the "Quick Try" part, you can get uCore run on QEMU. You will notice that when running in this way, uCore only comes with a very limited number of program, and their features are quiet limited.

However, uCore do have a compatible layer for ** Linux system calls **, making it possible to run native Linux applications on uCore (https://travis-ci.org/oscourse-tsinghua/ucore_plus?branch=master)

Support detail for architectures and features

Architectures

i386

AMD64

ARM

** WARNING! Running uCore+ on any ARM hardwares may void your warranty. We are not responsible for bricked devices, dead SD cards, and any kind of problems in your device. **

Goldfish
Raspberry Pi
Zedboard

To run uCore on Zedboard, you need to build u-boot and have a device tree file. We can extract those files from Arch Linux ARM for Zedboard:

wget http://os.archlinuxarm.org/os/ArchLinuxARM-zedboard-latest.tar.gz

Then follow the instructions on https://archlinuxarm.org/platforms/armv7/xilinx/zedboard to setup Arch Linux ARM for zedboard on a SD Card. You can skip the part of actually install Arch Linux, configuring the boot partition is enough.

To build uCore+ for Zedboard, run the following commands:

cd ucore
make ARCH=arm BOARD=zedboard defconfig
make sfsimg
make

The following devices is supported by uCore+ for Zedboard:

GPIO
Serial port
Programmable Logic

The driver is ported from u-boot source code, The driver create 2 char device files:
- /dev/zynq_programmable_logic
- /dev/zynq_programmable_logic_ctl
Writing to /dev/zynq_programmable_logic updates a kernel space buffer for the contents to be transported to ZynqPL. Those content is not transported to the ZynqPL controller, until a 0x00 or 0x01 is written to /dev/zynq_programmable_logic_ctl.

Writing 0x00 to /dev/zynq_programmable_logic_ctl means that you a transporting a full bit stream, and 0x01 stands for partial bitstream. Writing 0xFF clears the kernel space buffer.

The current implementation uses DMA and interrupt. But it's still very inefficient.

TODO: Implement mmap for kernel device file, or (better) implement sendfile / splice system call.
UIO Support The UIO support is prepared for Custom Zynq AXI PL Peripherals. Implementing a different device for every custom AXI PL Peripheral doesn't seems a good idea, because it leads to frequent change to kernel, yet these devices may have very simple interface. A UIO Device exposes a range of protected memory to user space, allowing the codes for the driver to be implemented in user space.

TODO: Implement mmap for kernel device file.

TODO: In standard UIO device, MMIO and DMA uses mmap system call. read system call is used for interrupt handling.

MIPS

Current Progress

We are working on ucore plus for amd64 smp porting. You can chekout the "amd64-smp" branch to see the newest progress of ucore plus.

Compile & Run on ARM

Refer to README_ZED.md.

Makefile

Cross Compile

set the environment variables:

export ARCH = ?

you can use archs: i386, arm, amd64, mips, or32, um, nios2

export CROSS_COMPILE = ?

(see Makefile in ./ucore)

Kconfig

The top level Kconfig is ./ucore/arch/xxx/Kconfig. You can include other Kconfig

(see ./ucore/arch/arm/Kconfig)

All config option is prefixed with UCONFIG_

Makefile

Supported variables: obj-y, dirs-y

(See ./ucore/kern-ucore/Makefile.build and Makefile.subdir)

Add a new ARCH

In arch/xxx, add Makefile.image and include.mk

***include.mk: define ARCH_INCLUDES and ARCH_CFLAGD, etc.

***Makefile.image: how to generate the executable for your platform.

***Kconfig: your top level Kconfig

***Makefile: recursively add Makefile in your arch directory.

oscourse-tsinghua/ucore_plus