Random references

FFI

Interface that allows code written in one language to call code written in another language

It sits between a program and a library, and handles, at runtime, the differences in ABI and marshalling of data between function calls

Audio

CLI

Remember to turn the term into a raw term

man cfmakeraw

Modify output style with CSI commands, ie:

CSI_CLEAR_ALL "\x1B[0J"
CSI_HIDE_CURSOR "\x1B[?25l"
CSI_SHOW_CURSOR "\x1B[?25h"
CSI_MOVE_TO_TOP_LEFT "\x1B[H"

Some UI Characters:

// ======================= //
// ┌─┬─┐  ╔═╦═╗
// ├─┼─┤  ╠═╬═╣
// │ │ │  ║ ║ ║
// └─┴─┘  ╚═╩═╝
// Reference: https://www.unicode.org/charts/PDF/U2500.pdf
//           0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
// U+250x    ─    ━    │    ┃    ┄    ┅    ┆    ┇    ┈    ┉    ┊    ┋    ┌    ┍    ┎    ┏
// U+251x    ┐    ┑    ┒    ┓    └    ┕    ┖    ┗    ┘    ┙    ┚    ┛    ├    ┝    ┞    ┟
// U+252x    ┠    ┡    ┢    ┣    ┤    ┥    ┦    ┧    ┨    ┩    ┪    ┫    ┬    ┭    ┮    ┯
// U+253x    ┰    ┱    ┲    ┳    ┴    ┵    ┶    ┷    ┸    ┹    ┺    ┻    ┼    ┽    ┾    ┿
// U+254x    ╀    ╁    ╂    ╃    ╄    ╅    ╆    ╇    ╈    ╉    ╊    ╋    ╌    ╍    ╎    ╏
// U+255x    ═    ║    ╒    ╓    ╔    ╕    ╖    ╗    ╘    ╙    ╚    ╛    ╜    ╝    ╞    ╟
// U+256x    ╠    ╡    ╢    ╣    ╤    ╥    ╦    ╧    ╨    ╩    ╪    ╫    ╬    ╭    ╮    ╯
// U+257x    ╰    ╱    ╲    ╳    ╴    ╵    ╶    ╷    ╸    ╹    ╺    ╻    ╼    ╽    ╾    ╿
// ======================= //

Latency

Latency Numbers Programmer Should Know

1-10 ns : L1 and L2 Cache
100-1000 ns : System call
10-100 µs : 1MB sequential read.
100-1000 µs : SSD Write. Intrazone (within AZ) network round trip.
1-10 ms : Interzone (AZ to AZ) round trip
100-1000 ms : TLS Handshake
1 s : 1GB Transfer interzone

Virtualization

Base components

KVM. Kernel module that handles CPU and memory communication
qemu. Emulation hardware components such as disk, network, usb, etc. It can emulate cpu, but most likely it will delegate it to the KVM
libvirt. High level api to manage virtualization components

Clients using libvirt

virsh: CLI that communicates with libvirt
virt-manager: GUI alternative to virsh
- virt-install
- virt-viewer

Linux Hypervisor Setup (libvirt/qemu/kvm)

(same in text)

Vim tricks

Manipulate a file in binary

:%!xxd
// to revert
:%!xxd -r

torijacarlos