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flat memory model (Global Descriptor Table entries are all full-width and overlapping (base is 0B and limit is 4GB), i.e. memory segmentation is unused / invisible)
cross-compilation and cross(?) grub:
# ./scripts/build-cross-compiler.sh # builds gcc targeting elf-i686 and binutils targeting elf-i686
# Or, the better alternative:
brew install i686-elf-gcc
brew install i686-elf-binutils
PYTHON=python3 ./scripts/build-grub.sh # builds grub and its dependencies, and uses the elf-i686 binutils and gcc above to compile grub
load environment to work on the OS (e.g. add (cross) elf-i686-gcc to $PATH) (should be done on the directory containing env.sh to correctly set $ROOT)
source env.sh
building kernel:
make
building iso file with grub and running:
make run
editing the make configuration
vim config/environment.make.config
the process is currently described as follows:
make variables are defined in config/environment.make.config
kernel/ contains the kernel code, kernel/makefile can build the kernel image $(OS_NAME).kernel (but requires libc/libk to be in sysroot), and can install the kernel and include header files to sysroot with make install (run in kernel/)
libc/ contains the freestanding libk and the hosted libc (to be developed) code, it compiles the libraries and saves them to sysroot with make install (in libc, or make -C libc install from $ROOT)
sysroot/ is a directory built when compiling the OS. It resembles the / file hierarchy in UNIX, storing the kernel in /boot and library headers in /usr/include and libraries in /usr/lib. It's used in compilation to store (first) all header files (so that the compilation succeedes), and then, for now, /usr/lib/libk.a (already required to be present here when building the kernel (-- that's why libc is built first)) and /boot/os_name.kernel
isodir/ is a directory built when creating the .iso bootable cdrom, and holds the kernel (copied from sysroot/boot/os_name.kernel) and GRUB config (copied from config/grub.cfg)
scripts/ contains useful scripts (for now scripts to build the cross compiler)
cross/ is generated when building the cross compiler, opt/ has the built cross compilation and grub binaries
env.sh is a script that sets the $ROOT environment variable to the project's root, and adds the cross compilation tools from opt/ to the $PATH environment variable
