1.2 Kernel Architecture & Syscalls

Kernel architecture, filesystem hierarchy (FHS), shell, and essential documentation.

1.2 Kernel Architecture & Syscalls

The Linux Kernel executes in Ring 0 (kernel space), whereas user applications run in Ring 3 (user space). Any interaction with hardware (networking, storage, memory) must traverse through a system call (syscall).

# Trace system call execution metrics
strace -c ls -la
# Inspect loaded kernel modules
lsmod | head -n 10

Filesystem Hierarchy Standard (FHS)

/etc: System-wide plain-text configuration files.
/var/log: System and daemon logs.
/proc and /sys: Virtual filesystems exposing live kernel state and hardware metrics.