Linux
These set of notes are Linux specific, check out OS page for general OS notes.
Recent / future developments
eBPF
eBPF: a handy way to build firewalls.
Extended Berkeley Packet Filter (eBPF) is an in-kernel virtual machine that runs user-supplied eBPF programs to extend kernel functionality.
A program is loaded into the kernel using the bpf
(2) syscall and is provided by the user as a binary blob of eBPF machine instructions. (e.g. can compile C programs to eBPF bytecode, clang -target bpf
)
C Library: libbpf
Microsoft chose to port eBPF into Windows rather than try to duplicate its functionality with its own program.
iptables
is a firewall that is built into the Linux kernel. It allows you to filter and manipulate network traffic based on a set of rules that you define. eBPF is more flexible than iptables
. eBPF is best suited for more complex tasks that require custom programs to filter and manipulate network traffic.
iptables => nftables
nftables
is the new packet-filtering portion of Netfilter. nft
is the new userspace utility that replaces iptables
, ip6tables
, arptables
and ebtables
.
io_uring
io_uring
allows Linux to launch an operation asynchronously and wait for its completion. (predecessor: asynchronous I/O (AIO) subsystem)
io_uring
uses a memory ring buffer shared between user space and the Linux kernel. This enables it to submit operations and collect the results without needing time-expensive Linux kernel calls. Its API is complex, but if your applications require lots of I/O, you get rewarded with vastly improved increased performance.
cgroup v2
Read more: cgroup
systemd
The init system. Read more: systemd
Wayland
Replacing X11.
Security
The Linux Unified Key Setup (LUKS) is a disk encryption specification.
What is vmlinuz?
vmlinuz is the compressed image of the kernel. It gets uncompressed, loaded into memory, and executed at boot.
What is a generic Linux kernel image
The one that the distribution's developers create specifically to boot on a wide variety of hardware; the device drivers for this generic kernel image are included as loadable kernel modules.
What is Linux-libre?
A modified version of the Linux kernel that contains no binary blobs, obfuscated code, or code under proprietary licenses.
License: GPL v2.