iruel

iruel is a small x86_64 toy kernel with a userspace, ramfs root filesystem, and a shell. it boots directly in qemu from the kernel image and runs userspace ELF binaries embedded into the kernel as an initramfs

build

make -j4

run

make run

the serial console is used for input and output. after boot, the shell runs on the same console

shell

built-ins:

• help
• uname -a
• id
• exit

features:

• built-in tools and external commands in /bin
• no pipes or redirection

user tools

• ls
• cat
• echo
• pwd

process model

• fork, execve, waitpid for userspace
• round robin scheduling with a run queue
• sleep/wakeup for blocking operations

filesystem

• in memory ramfs with standard directories created at boot: /bin, /etc, /dev
• userspace binaries are embedded into the kernel at build time and exposed under /bin
• procfs mounted at /proc with uptime and per-pid status