Lenshood

There was a very interesting lab in the course of Unsupervised Learning, Recommenders, Reinforcement Learning taught by Prof. Andrew Ng, which trains a machine learning model to make sure the lunar lander land in a pre-defined range of area. In the course, Andrew also mentioned one of his team's great work that using machine learning model to drive a toy helicopter flying inverted in the real word. That's amazing, the work they have done has been published: Autonomous Helicopter Aerobatics through Apprenticeship Learning.

The entire lab is based on the Gymnasium, which provides experiential environments for reinforcement learning. After finished the lab, I noticed the Gymnasium is quite flexible and easy to extend, making it possible to play the env in some fancy ways beyond the default configuration.

自各类计算机程序开始被编写、运行开始，我们就一直想通过各种方式来了解它的执行过程和状态从而判断计算机程序运行的行为和效率。作为被使用最广泛的操作系统，Linux 经过多年发展，拥有了各类工具和组件来实现对用户程序以及内核程序的追踪，这些组件组成了 Linux 的追踪（Tracing）系统，它的魔力令人着迷。

本文将从最基础也是最灵活的 Kprobes（Kernel Probes） 入手，了解 Linux Tracing 系统的设计（本文基于 linux kernel v6.15.4）。

Based on disk and file management, now we are able to store the user space program on the disk, and let them run after kernel started. But before that, there is still a topic we haven't covered: how does xv6 jump from kernel space to user space?

After all, the content we talked about in previous chapters is only limited in the supervisor level, even machine level, where the code has full control of hardware. However, the user space program cannot be granted such huge scope of control, then we should know how to jump from kernel space to user space, so that we could provide a safer environment for the user program.

In this chapter, we are going to find it out.

With all of the content in the previous chapters, we have known how to initialize and run a process, but before the kernel runs the first line of a process's code, a question still remained, how does my user program store in the disk and how is it loaded?

In this chapter, we are going to discover the disk management and file system in the xv6, we'll see the persistence stack from the top to the bottom, let's get started!

In this chapter, we are going to explore the cpu virtualization, also known as process, in the xv6.

I'm really excited about writing this chapter, because process is one of the fundamental concepts of the operating system. Process is very useful for multiple tasks, and in the design wise, its abstraction is also very elegant.

We have learnt how to setup risc-v in rust, and also initialized risc-v to be able to print format strings, in this chapter we are taking the first look of the OS kernel, and will try to figure out the memory management in xv6.

With the help of the previous article, right now we have a good foundation for running rust on risc-v platform.

In the second episode, we are going to jump into some real code of xv6, and take care of the initialize from machine level to supervisor level, and finally, make the printf!() macro available in our code!

Xv6 is one of the best operating systems for teaching. It’s a great way to learn about how an OS works with basic functions and few lines of code.

Originally, xv6 was written in C, which is awesome for students to get hands-on experience with such a classic programming language. But now that Rust is gaining traction—especially since rust-for-linux is becoming a part of the main line Linux—wouldn’t it be fun to run xv6 using Rust?

As a perfect way to kill time, I have migrated most of xv6 from C to Rust. You can check it out here. During this migration process, I encountered many sorts of issues and tricky stuff, nothing brings me more satisfaction than successfully resolving a problem!

Therefore, I believe it would be cool for me to share my experiences through a series of articles detailing how I did this, complete with a more structured approach and clear procedures.

All right, let's get started...

本文翻译自 Gregor Resing（IBM）的文章 The Software Defined Vehicle。

当今的汽车与数年前的汽车相比，虽然作为载具的主要目的变化不大，但不论是在驾乘体验、智能化水平还是交互方式上，都发生了质的飞跃。

为了能支撑新一代汽车所提供的这种智能化服务水平，显而易见，需要将软件平台与硬件平台相互分离和抽象以提升灵活性，这种被称为软件定义汽车（Software Defined Vehicle，下文简称 SDV）的设计方法基于更加灵活和易于扩展的软件作为汽车的核心，将传统的汽车升级为拥有诸如智能驾驶、深度娱乐、个性化人机交互能力的 “第三空间”。

SDV 带来了一系列汽车设计的革命性跨越，同时也引入了各种新的困难。诸如性能、可靠性、安全性、易用性等在软件领域长期存在的跨领域、跨业务型挑战，随着 SDV 被一并引入了汽车领域。