Reimplementation and extension of the teaching operating system xv6 on multiple platforms.

Architectures (to be) included: ARM, MIPS64, i386 (the original xv6 implementation)

Our first goal is to port xv6 onto ARM and MIPS64 (Loongson 2H).

The guides to organize source codes can be found in each directory under FILE.

Remember to add license information on top of the source code :)

This repository supersedes xv6-Loongson3A, the code from which will be migrated there.

Please refer to the doc directory for documentations.

Ideally, the project should be compiled by the latest GCC (or cross-GCC if cross-compiling) toolchain available on Linux distro.

If prebuilt packages are not available, please use precompiled binaries and libraries provided by manufacturers.

If you're a determined, patient geek, you can build your own cross-compiler from source code, as illustrated below.

Fedora ships cross-compiler packages since release 18, and there's really no reason to keep using unsupported old versions.

To install MIPS toolchain, execute (replace dnf with yum if you're running older release)

# dnf install gcc-mips64-linux-gnu

Installing ARM toolchain is similar:

# dnf install gcc-arm-linux-gnu

Cross-compilers are provided in sid, or unstable branch in Debian.

Unfortunately, one should usually upgrade to unstable from testing, which, in turn, should be upgraded from stable.

If you don't want to risk your machine being "unstable" (though not unstable as it seems - Ubuntu is based on Debian unstable branch), or regard the whole process as troublesome, simply jump to the Third-party section.

Upgrading between branches is simply done by modifying /etc/apt/sources.list and changing sources from testing to unstable.

After upgrading, the toolchains could be installed by

$ sudo apt-get install gcc-4.9-arm-linux-gnueabi

if you're playing with ARM board, or

$ sudo apt-get install gcc-4.9-mipsel-linux-gnu

if you're hacking a Loongson box.

Replace 4.9 with 5 if you want to try GCC 5.

Awkwardly, Ubuntu ships gcc-4.9-arm-linux-gnueabi, but does not ship the MIPS equivalent.

For ARM developers, running

$ sudo apt-get install gcc-arm-linux-gnueabi

would do everything.

Obtaining MIPS toolchain is somewhat more complicated. First, you need to install gdebi:

$ sudo apt-get install gdebi

Download and install by gdebi the following .deb packages from Debian sid repository, in the order given:
binutils-mipsel-linux-gnu
cpp-4.9-mipsel-linux-gnu
gcc-4.9-mipsel-linux-gnu

Loongson provided the compiler suite for building kernel here However, Loongson only supports GCC 4.4.0, which is quite obsolete compared to the now-popular version 4.9.x or 5.x.x.

Another good choice is Sourcery Codebench from Mentor Graphics. The MIPS toolchain archive could be downloaded here.

$PATH (and $LD_LIBRARY_PATH for Loongson's compiler) should be modified accordingly to contain the binaries and libraries provided. Read /etc/profile and put the paths into appropriate files and/or locations.

(TODO: add third-party ARM cross-compiler providers)

(TODO: write source build instructions for ARM/IA32/MIPS)