Category: Tutotial

How to launch ARM aarch64 VM with QEMU from scratch

  • Haco
  • February 5, 2025
  • 3 min read

The below instructions will allow for bringing up an ARM VM from scratch. To launch an aarch64 VM we first need to install a few dependencies, including QEMU and the qemu-efi-aarch64 package, which includes the efi firmware. apt-get install qemu-system-arm apt-get install qemu-efi-aarch64 apt-get install qemu-utils Create the flash images with the correct sizes. dd if=/dev/zero of=flash1.img bs=1M count=64 dd if=/dev/zero of=flash0.img bs=1M count=64 dd if=/usr/share/qemu-efi-aarch64/QEMU_EFI.fd of=flash0.img conv=notrunc Create a dedicated directory (folder) on your host system to contain this virtual machine. Download the latest  “Virtual” ISO file for…

Understanding the LLVM Compiler

  • Haco
  • December 19, 2024
  • 21 min read

Components of LLVM: LLVM is designed with a three-phase architecture: Frontend, Middle-end, and Backend. Each component plays a crucial role in translating high-level source code into machine-executable code, while allowing modularity and optimizations across different languages and architectures. 1. Frontend The frontend is responsible for: Parsing the high-level source code (written in languages like C, C++, Rust, etc.). Checking for syntax and semantic correctness. Generating the LLVM Intermediate Representation (IR), which is an abstract, platform-independent code representation. Key Processes in the Frontend: Lexical Analysis (Tokenization): The source code is broken into meaningful chunks called tokens (e.g.,…

【计算机体系结构】Tomasulo算法

  • Haco
  • December 18, 2024
  • 3 min read

1、数据冒险 数据相关有四种，分别是RAR、WAR、WAW、RAW。其中“RAR”不会影响指令的执行，所以提数据相关的时候一般忽略，而WAR、WAW、RAW的重要差别就出在“数据依赖”上。“WAR”和“WAW”这两种数据相关其实没有数据依赖，即发生冒险的指令之间其实没有数据流动，通过寄存器重命名就可以消除冒险。“RAW”冒险则无法解决，因为后序指令读取的数据由前序指令算得，这个过程有明确的数据依赖。 2、Tomasulo算法 Tomasulo是计算机硬件架构的一种指令动态调度算法，其通过寄存器重命名消除了假数据冒险，提高了机器的乱序性能。Tomasulo算法的调度分为三个步骤：发射、执行、写回。 Tomasulo算法的实现结构 发射：Tomasulo算法是顺序发射的，即指令按照程序中的顺序一条接一条被发射到保留站。判断能否发射的唯一标准是指令对应通路的保留站是否有空余位置，只要保留站有空余，就可以把指令发射到保留站中。周期结束时会更新保留站和寄存器结果状态表，如果指令有可以读取的数据，就会立刻拷贝到保留站中；寄存器结果状态表中总是存有最新的值，即如果后...

RISC-V simulation with Qemu

  • Haco
  • September 27, 2024
  • 5 min read

Installation of Qemu On the Qemu website, you can find a lot of information on how to get it running. But for the specific purpose of this tutorial, a few important extra steps are needed. In order to use the user mode simulation, your host system must be Linux. I recommend installing from source as described on this  using configure with --target-list= riscv32-linux-user,riscv64-linux-user, riscv32-softmmu,riscv64-softmmu as a configuration. I assume you have a RV toolchain running, if not,  is how. User-Mode The simplest way of getting an environment for RV programming is…

Installing & Building RISC-V Toolchain

  • Haco
  • September 27, 2024
  • 2 min read

Prerequisites Several standard packages are needed to build the toolchain $ sudo apt-get install autoconf automake autotools-dev curl python3 python3-pip libmpc-dev libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo gperf libtool patchutils bc zlib1g-dev libexpat-dev ninja-build git cmake libglib2.0-dev libslirp-dev Create a directory and clone $ mkdir ~/riscv && cd ~/riscv $ git clone https://github.com/riscv/riscv-gnu-toolchain Configure and make $ mkdir /opt/riscv $ ./configure --prefix=/opt/riscv $ make linux Your tool will be available on /opt/riscv/bin Add /opt/riscv/bin to PATH Edit the ~/.bashrc file $ sudo vim ~/.bashrc Add below at the end of the file and…