Giacomo Tesio
890f126abc
OREAD and OWRITE are used as array indexes assuming that OREAD was zero and OWRITE was one. Thus each related allocation reserved just 2 slot and even Ep struct in usb.h reserved just 2 int for toggles. Since OREAD is now 1 and OWRITE is 2 we have to allocate/reserve 3 slot as long as we use them as array indexes (which we could change in the future). Unfortunately this means we waste the index zero in those arrays that will always be unused. This also means that, to loop in such arrays we must begin with OREAD as index zero is always empty. PRO-MEMORIA: if/when we introduce the walk() syscall, OSTAT might turn useless. In that case we might remove it and thus consider to move back OREAD/OWRITE to 0/1 respectively (which might or might not be a good idea, to be analyzed).
Jehanne
Jehanne is a simple operating system.
Jehanne has noble ancestors:
- most of userland tools, a lot of wisdom and some kernel modules, come from 9front
- the kernel is a fork of Charles Forsyth's Plan9-9k
- most of the build system and some valuable piece of code come from Harvey OS
Still the project is named after a humble peasant, the famous French heretic Joan of Arc, because it diverges deeply from the design and conventions of its predecessors.
Overview
This is the main repository, used to build the system as a whole:
- arch contains one folder for each supported architecture, with specific C headers, libraries and executables (note that by architecture we intend any kind of physical or virtual machine that is able to run code, thus rc is actually an architecture)
- sys is the system folder
- doc contains useful documentation for Jehanne development
- hacking contains the utilities used to develop Jehanne
- qa contains the regression tests
- mnt contains default mount targets
- usr contains the users' folders
- pkgs will contains the installed packages
The running system also includes supplemental folders like /lib,
/cmd and /dev that are bound during the boot as required.
Build
To build Jehanne and play with it, you need to have git, golang, qemu, gcc, binutils and bison installed. For example on Debian GNU/Linux you should be able to get going with
sudo aptitude install git golang build-essential bison qemu-system
After the repository clone, you can give a look with
git submodule init # we have a lot of submodules
git submodule update --init --recursive --remote
./hacking/devshell.sh # start a shell with appropriate environment
./hacking/continuous-build.sh # to build everything (will take a while)
./hacking/runOver9P.sh # to start the system in QEMU
./hacking/drawterm.sh # to connect Jehanne with drawterm
Hacking
Jehanne is a work in progress. Forks and pull requests are welcome.
In doc/hacking you will find all you need to know about its principles, design and weirdness.
There's a lot of work to do, in every area of the system.
To coordinate our efforts, we use the github issues. To discuss (and even debate) about the design and development of Jehanne we use the JehanneOS mailing list: please join and present yourself and your attitudes.