DEVELOPMENT(7)

NAME
development - operating system development instructions

SYNOPSIS
/src

DESCRIPTION
Releases come with the system source code in /src as a git(1) repository. It can be modified, compiled and installed on the current system. The source code is built with a make(1) build system. The source code can be located in any location, if so, simply substitute /src with the real location. These instructions only apply to building the operating system from within itself, those building it from another operating system needs to follow cross-development(7) instead.

If you are building a new version of the operation system where build tools have been added or changed, you first need to install the new tools. This is not needed when building the matching release. To do so, run as root:

        cd /src
        make distclean            # fully clean build directory
        make install-build-tools  # install new tools
        make clean-build-tools    # clean for real build below

To build the base operating system and upgrade the current system, run as root:

        cd /src
        make            # build new operating system in /src/sysroot
        make sysmerge   # upgrade current operating system with /src/sysroot

The build system creates a minimal root filesystem structure in the /src/sysroot and builds each operating system component in turn, installing them into the sysroot. If the source code for ports are placed in /src/ports then they are automatically built as well. The result is a minimal system that can be turned into working system by adding important configuration such as passwd(5).

The sysmerge make target ensures a system is built in /src/sysroot and then runs the sysmerge(8) program which installs the new system files onto the existing system. It updates the system manifest as well all ports installed in the sysroot. The initrd(7) is automatically regenerated using update-initrd(8). The bootloader, if enabled in upgrade.conf(5), is reinstalled and configured as necessary. The new user-space is running on completion, though existing processes will be running the old programs. A reboot is needed to run the new kernel. If the ABI changed and the current kernel isn't able to run the new programs, then the upgrade is delayed and will be automatically completed on the next boot. The sysmerge-wait make target forces waiting until the next boot.

  Root Makefile
The /src/Makefile handles the high level build of the operating system. The important targets are:

all (default) Build each component in turn and install them into the sysroot.

build-tools
    Make all build tools.

clean
    Clean the component directories and the port source code. (clean-core, clean-ports)

clean-build-tools
    Clean the directories of all build tools.

distclean
    Run every clean target such that the source code is ready for distribution. (clean-builds, clean-core, clean-ports, clean-release, clean-repository, clean-sysroot)

install-build-tools
    Install all build tools after making them.

iso Create a release iso in the /src/builds directory after making all.

mostlyclean
    Clean everything except binary packages. (clean-builds, clean-core, clean-ports, clean-release, clean-sysroot)

release
    Make iso and construct release directory tree in /src/release suitable for online publishing.

sortix.iso
    Make iso and place it in the current directory as sortix.iso.

sysmerge
    Upgrade the current operating system using the sysroot after making the all target.

sysmerge-wait
    Like sysmerge but delay the upgrade until the next boot.

sysroot-base-headers
    Create the sysroot and install only the headers of the standard library and kernel into it. This is useful when bootstrapping the runtime libraries of the compiler that need to know about libc prior to building libc.

The important environment variables influencing the Makefile are:

BUILD
    The platform of the current operating system. This defaults to the current machine and operating system.

HOST
    Specifies platform on which the compiled code will run. This defaults to the current machine and operating system. This is used when cross-compiling the operating system. When cross-compiling the operating system, it must be set to one of i686-sortix and x86_64-sortix. This must be unset when building the build tools as they run on the current operating system. The compiler tools are prefixed with this variable if it does not match BUILD.

OPTLEVEL
    Specifies compiler optimization options that gets added to CFLAGS and CXXFLAGS.

SORTIX_INCLUDE_SOURCE
    Specifies whether the source code is included in the sysroot. This must be one of no, yes or git and defaults to git if git(1) is installed and yes otherwise.

SORTIX_ISO_COMPRESSION
    Specifies the compression algorithm used in iso files. This must be one of none, gzip or xz and defaults to xz.

  Components
The operating systems components, such as libc and the kernel, each have their own directory by that name. It contains a makefile that can build and install that component. This allows building and installing only that component onto the current operating system.

For instance, to build and install libc, run as root:

        cd /src/libc
        make
        make install

System libraries are statically linked and you will have to relink programs with the new library for changes to take effect. Building the whole operating system from the root makefile ensures components are built in the right order such that all programs use fresh libraries. The root makefile invokes component makefiles with SYSROOT set to /src/sysroot to force the compiler to locate files there. Likewise when installing, it sets DESTDIR to /src/sysroot to make it install files there.

  Directories
In addition to the directories for each operating system component, there are these special directories:

/src/ports
    If this directory exists, each subdirectory can contain the source code for a port that gets built along with the rest of the system.

/src/release
    The release root makefile target creates this directory and populates it with a directory structure suitable for online publishing of a release.

/src/repository
    If ports are present, this directory is made when binary packages are built and they are stored here. This works as a cache so ports don't have to be rebuilt every time the operating system is. Packages are also copied from here rather than the sysroot when making releases.

/src/sysroot
    This directory is made when building the operating system and the freshly made files are installed here. The build system uses this as the system root which forces the compiler to look here for headers and libraries. This ensures a clean bootstrap where files from the current operating system do not leak into the new system.

/src/sysroot-overlay
    If this directory exists, it is added to the initrd of the produced iso and can contain additional system files.

  Build Tools
Some components are used to build the source code and must match the versions in the source code being built. These are currently:

•   carray
•   kblayout-compiler
•   mkinitrd
•   sf
•   tix

If the currently installed versions of those tools are older than the ones in the source code, you must update them. The clean-build-tools root makefile target cleans the applicable directories, the build-tools root makefile target builds them from the source code, and the install-build-tools root makefile target installs the new version. You must clean the compiled files from the source code afterwards because the compiled tools are intended to run on the current system, and have not been built properly using /src/sysroot.

  Ports
You can place the source code for ports in srctix(7) format (has a tixbuildinfo(7) file) in the /src/ports directory and they will get built automatically when and installed into the sysroot when building the whole operating system. Installable binary packages are created in the /src/repository/$HOST directory using tix-build(8) directory and can be installed with tix-install(8). If an existing binary package exists in the repository, it is used instead of the building the port again.

Ports are currently made using cross-development(7) as not all ports can be built natively yet.

The ports system is described in detail in porting-guide(7).

  Patches
The source code is managed as a git(1) repository and you can make your own changes and commit them. A good approach is to set up your own local development branch and work there:

        git checkout -b local
        git add utils/hello.c
        git commit -m 'Add hello(1).'

You can then easily prepare your a set of patches for upstream submission:

        git format-patch master..local

This will create a series of .patch files containing your changes. Review them and rewrite git history as needed until they are of submittable quality. You can then submit them for review at the official website.

To transfer files out of the operating system, you can either mount the local root filesystem from another operating system with networking, or you transmit the patches over the serial connection as described in serial-transfer(7).

  Releases
CD-ROM release of the operating system can be built with the iso root makefile target. This will build the whole operating system, if not done already, and produce a bootable iso for the current architecture in the /src/builds directory. The sortix.iso root makefile target will do the above and place a sortix.iso file in the current directory.

The release root makefile target will run the iso target and prepare a /src/release directory with a directory structure and miscellaneous files suitable for a formal online release.

SEE ALSO
git(1), make(1), cross-development(7), installation(7), porting-guide(7), serial-transfer(7), upgrade(7), sysinstall(8), sysmerge(8), update-initrd(8)