从树莓派开始

        树莓派是在嵌入式领域颇受欢迎的“便携PC”，在创客世界里，有众多的创意都是通过该平台实现。从产品设计的角度，该平台需要提供简单开放的开发模式给各大开发者使用，而事实证明，这是成功。因为其生态已经悄然成熟，无论硬件，还是可参考资源，漫天飞——搭建一个特定功能的平台，可能是三下五除二的事情。不过，这里，不会涉及简单的应用开发或者移植，仅是利用该平台，做一些不一样的事情——从系统构建，驱动原理，内核以及性能优化等诸多方面进行深入探究。

        让人兴奋和惊讶的事是，ubuntu对树莓派进行了大力的支持（包含32bit/64bit）。ubuntu的资源获取相对比较便捷，并且和普通x86 PC，亦可以做为对比的学习，甚是快哉！

 

相关环境：

• 树莓派3B(这是尘封已久的板子，4b暂时就不买了，期待最新的出来)
• ubuntu linux-5.4.0 aarch 64

        对应的固件从ubuntu官方可以直接下载：https://ubuntu.com/download/raspberry-pi

 

当然，安装好系统，自然是迫不及待下载内核源码（ubuntu资源下载就是方便）：

ubuntu@ubuntu:~$ sudo apt-get install linux-source-5.4.0
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  libncurses-dev | ncurses-dev kernel-package libqt3-dev
The following NEW packages will be installed:
  linux-source-5.4.0
0 upgraded, 1 newly installed, 0 to remove and 70 not upgraded.
Need to get 134 MB of archives.
After this operation, 149 MB of additional disk space will be used.
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
0% [1 linux-source-5.4.0 147 kB/134 MB 0%][  319.276056] Under-voltage detected! (0x00050005)
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-updates/main arm64 linux-source-5.4.0 all 5.4.0-42.46 [134 MB]
24% [1 linux-source-5.4.0 40.7 MB/134 MB 30%]                 232 kB/s 6min 44s[  916.019751] Under-voltage detected! (0x00050005)
Fetched 119 MB in 17min 35s (113 kB/s)                                         
Selecting previously unselected package linux-source-5.4.0.
(Reading database ... 104204 files and directories currently installed.)
Preparing to unpack .../linux-source-5.4.0_5.4.0-42.46_all.deb ...
Unpacking linux-source-5.4.0 (5.4.0-42.46) ...
[ 1373.657829] Under-voltage detected! (0x00050005)
Setting up linux-source-5.4.0 (5.4.0-42.46) ...
ubuntu@ubuntu:~$ ls
linux-rspi-5.4.y.tar.gz