Taihsiang Ho tai271828

The Freenode resignation FAQ, or: "what the fuck is going on?"

IMPORTANT NOTE:

It's come to my attention that some people have been spamming issue trackers with a link to this gist. While it's a good idea to inform people of the situation in principle, please do not do this. By all means spread the word in the communities that you are a part of, after verifying that they are not aware yet, but unsolicited spam is not helpful. It will just frustrate people.

Update 3 (May 24, 2021)

A number of things have happened since the last update.

Adding Sections to ELF Binaries

Suppose you need to add a section to an ELF binary to contain information gathered at compile time, but to be used at link time or run time. Here's how to add a section named .okdata and either populate it with data either after or before emitting the ELF binary.

Adding a Section After Emitting

In this case, you'll add file’s contents to an already existing binary. objcopy copies and translates object files, such that adding a new section is a matter of writing that new section’s contents into the ELF file.

(Optional) Create a simple program’s object file.

Memo Date: 2018-07-18 MAAS version: 2.3

Curtin’s assumption is that a fairly rich Linux (Ubuntu) environment is booted.

But if your image is not Linux (Ubuntu) based, you could customize the image via:

Understand curtin stages
http://curtin.readthedocs.io/en/latest/topics/config.html
Stages:

Setting up Qemu with a tap interface

There are two parts to networking within QEMU:

The virtual network device that is provided to the guest (e.g. a PCI network card).
The network backend that interacts with the emulated NIC (e.g. puts packets onto the host's network).

Example: User mode network

Running Ubuntu 16.04.1 armhf on Qemu

This is a writeup about how to install Ubuntu 16.04.1 Xenial Xerus for the 32-bit hard-float ARMv7 (armhf) architecture on a Qemu VM via Ubuntu netboot.

The setup will create a Ubuntu VM with LPAE extensions (generic-lpae) enabled. However, this writeup should also work for non-LPAE (generic) kernels.

The performance of the resulting VM is quite good, and it allows VMs with >1G ram (compared to 256M on versatilepb and 1G on versatile-a9/versatile-a15). It also supports virtio disks whereas versatile-a9/versatile-a15 only support SD cards via the -sd argument.

Get netboot files

Making a UEFI bootable iPXE USB drive

Build the UEFI executable for iPXE

# First we'll clone iPXE
$ git clone git://git.ipxe.org/ipxe.git
# Go into the src directory of the cloned git repo
$ cd ipxe/src
# Compile the UEFI iPXE executable

Debugging curtin from within MAAS

Deploying a node with MAAS cli

You can deploy a node with the maas cli which is often preferable to clicking a button on a web UI.

$ SYSTEM_ID=node-787b19d8-d25c-11e4-9f9e-00163eca91de
$ NAME="random-nodename"
$ MAASNAME="maaslocal"

$ maas $MAASNAME machine allocate "name=$NAME"

	# For recent versions of Ubuntu:
	- https://www.pugetsystems.com/labs/hpc/ubuntu-22-04-server-autoinstall-iso/

	# Docs:
	- https://wiki.ubuntu.com/FoundationsTeam/AutomatedServerInstalls
	- https://wiki.ubuntu.com/FoundationsTeam/AutomatedServerInstalls/ConfigReference
	- https://cloudinit.readthedocs.io/en/latest/topics/datasources/nocloud.html
	- https://discourse.ubuntu.com/t/please-test-autoinstalls-for-20-04/15250/53

	# Download ISO Installer:

	/// Make CPUs usage as a sin wave

	#include <math.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <sys/time.h>
	#include <unistd.h>

	const float PI = 3.1415926;
	const int TIME_SLICE = 40000; // 40 ms

	wget -nc http://ftp.debian.org/debian/dists/jessie/main/installer-amd64/current/images/netboot/debian-installer/amd64/linux
	wget -nc http://ftp.debian.org/debian/dists/jessie/main/installer-amd64/current/images/netboot/debian-installer/amd64/initrd.gz
	cp -nv ~/.ssh/id_rsa.pub .
	qemu-system-x86_64 -machine accel=kvm -kernel linux -initrd initrd.gz -m 1G -smp 2 -append "blacklist=vga16fb fb=false video=false vga=normal auto=true url=http://10.0.2.10:8080/debian-preseed.txt hostname=otto domain=" -net user,guestfwd=:10.0.2.10:8080-cmd:"/bin/busybox httpd -i" -hda /dev/shm/deb.img -net nic -display none