# 安装硬件模拟器

## 下载安装QEMU

我们也像安装编译器一样，去sifive的官网[下载](https://static.dev.sifive.com/dev-tools/riscv-qemu-4.2.0-2020.04.0-x86_64-linux-ubuntu14.tar.gz?_ga=2.19251771.2004657256.1596986275-1484936641.1596986275)Ubuntu系统的riscv-qemu，里面的很多设置都已经设置好了的。在下载完，然后解压到之前的riscv文件夹下，把里面的bin文件夹加入到环境变量。修改完记得重启虚机噢。（这次熟练多了吧\~）。

## 使用OpenSBI

新版 Qemu 中内置了 OpenSBI 固件（firmware），它主要负责在操作系统运行前的硬件初始化和加载操作系统的功能。我们使用以下命令尝试运行一下：

```
qemu-system-riscv64   --machine virt   --nographic   --bios default
```

如果成功的话，就可以看到。

```
OpenSBI v0.5 (Oct  9 2019 12:03:04)
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name          : QEMU Virt Machine
Platform HART Features : RV64ACDFIMSU
Platform Max HARTs     : 8
Current Hart           : 0
Firmware Base          : 0x80000000
Firmware Size          : 116 KB
Runtime SBI Version    : 0.2

PMP0: 0x0000000080000000-0x000000008001ffff (A)
PMP1: 0x0000000000000000-0xffffffffffffffff (A,R,W,X)
```

可以看到我们已经在 `qemu-system-riscv64` 模拟的 `virt machine` 硬件上将 `OpenSBI` 这个固件 跑起来了。Qemu 可以使用 `Ctrl+a` 再按下 `x` 退出（注意要松开`Ctrl`再单独按`x`）。

如果无法正常使用 Qemu，可以尝试下面这个命令。

```
$ sudo sysctl vm.overcommit_memory=1
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://nankai.gitbook.io/ucore-os-on-risc-v64/lab0/pei-zhi-huan-jing/an-zhuang-ying-jian-mo-ni-qi.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.