sMezaOrellana

Extending The xv6 Kernel - Adding A System Call

This document show how you can extend the xv6 kernel by a new system call, getppid(). We do this by modifying the syscall.h, syscall.c and sysproc.c files in the kernel code and modifying user.h and usys.S in the user space code.

Introduction

The xv6 kernel, henceforth referred to as the kernel, is a re-implementation of the unix version 6 kernel. Originally written by Dennis Ritchie and Ken Thompson in 1975 using the C programming language. The kernel targets two architectures: x86 and risc-v . this document focuses on the x86 version. Xv6 is an operating system developed in 2006 by MIT for educational purposes. It is used in MIT’s undergraduate course: CS 6.1810: Operating Systems Engineering . The complete implementation of xv6 is around 6000 lines of code which makes it ideal to study and understand the main concepts of an (unix) operating system.

Installation & Building

If you want to play around with the kernel you will need the f

aalmiramolla

# references:
#   Learning by doing: Writing your own traceroute in 8 easy steps (Ksplice Blog)
#   https://blogs.oracle.com/ksplice/entry/learning_by_doing_writing_your

# Edited by: Alejandro Almira <laboral at alejandroalmira.com>

import datetime
import socket
import sys

ityonemo

A half-hour to learn Zig

This is inspired by https://fasterthanli.me/blog/2020/a-half-hour-to-learn-rust/

Basics

the command zig run my_code.zig will compile and immediately run your Zig program. Each of these cells contains a zig program that you can try to run (some of them contain compile-time errors that you can comment out to play with)

graninas

At the beginning of 2030, I found this essay in my archives. From what I know today, I think it was very insightful at the moment of writing. And I feel it should be published because it can teach us, Rust developers, how to prevent that sad story from happening again.

---

What killed Haskell, could kill Rust, too

What killed Haskell, could kill Rust, too. Why would I even mention Haskell in this context? Well, Haskell and Rust are deeply related. Not because Rust is Haskell without HKTs. (Some of you know what that means, and the rest of you will wonder for a very long time). Much of the style of Rust is similar in many ways to the style of Haskell. In some sense Rust is a reincarnation of Haskell, with a little bit of C-ish like syntax, a very small amount.

Is Haskell dead?

afresh1

These examples all live in a default server block in your httpd.conf(5).

server "default" {
	listen on * port 80
	... # all the location blocks can together right here
}

We'll be using slowcgi(8) as the example, because with the -d flag it helpfully spits out the FastCGI environment it got from httpd(8) and what it's planning to do with that.

llandsmeer

#include <stdio.h>
#include <stdlib.h>
#include <libtcc.h>

void callme(int x) {
    printf("hello, %d\n", x);
}

void error_func(void * user, const char * msg) {
    printf("TCC Error: %s\n", msg);

ausfestivus

List of Azure Regions

A list of all the region names and locations for Azure

Creating the list

You can recreate the list anytime using this command:

az account list-locations -o table

janlelis

ruby -e'_,__="",binding;loop do$><<">> "if$/>_
puts"=> %p"%[__.eval(_+=gets||exit!),_=""]
rescue Exception
puts"\e[31m%p\e[0m"%[$!,_=""]if/d e|ee/!~"#$!"end'

ClaesBas

How to install OpenBSD with bhyve-vm on SmartOS (20190424):

tl;dr:
  Create a bhyve vm with an empty disk, where you put an install image with dd afterwards.
  "bhyve_extra_opts": "-w"
  "bootrom": "uefi"
  "vcpus": 1 (is needed too, some say..)
  Change to serial console when booting the install image

Do it like this:

lisawolderiksen

Using Git Commit Message Templates to Write Better Commit Messages

The always enthusiastic and knowledgeable mr. @jasaltvik shared with our team an article on writing (good) Git commit messages: How to Write a Git Commit Message. This excellent article explains why good Git commit messages are important, and explains what constitutes a good commit message. I wholeheartedly agree with what @cbeams writes in his article. (Have you read it yet? If not, go read it now. I'll wait.) It's sensible stuff. So I decided to start following the