Raspberry Pi 樹莓派編譯新核心

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前陣子在家門口踢到一個…

Raspberry Pi 二代目 Model B，然後就 過著開開心心的生活 開始想把一堆東西裝上去然後不知道要幹嘛!?書房的 Hub 滿了，所以我就要拿出之前買的 小米隨身WiFi 拿出來插上…

就會發現，什麼事都沒有發生。因為…Driver 沒有進 Kernel 根據非官方 Github 上的 Repo 顯示：

This repository is based on the original driver released by MediaTek which was rejected from Linux kernel because of the poor code quality.

嗯！所以展開自編之路…

故事一波三折，曲折離奇…先進入正題

準備環境

我的環境是 Ubuntu 64bit

λ ~/uname -a
Linux ubuntu 3.13.0-35-generic #62-Ubuntu SMP Fri Aug 15 01:58:42 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

創一個資料夾來放等等要下載的東西

λ ~/mkdir ~/rasp

注意 以下的 git clone 會帶 --depth 1 表示我們只抓預設 branch 的最後一個 commit 這是為了加快下載速度以及節省空間

Raspberry Pi Toolchain (download)

λ ~/rasp/ git clone https://github.com/raspberrypi/tools --depth 1

toolchain 位於下面位置

λ ~/rasp/ ls tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-*
tools/../../bin/arm-linux-gnueabihf-addr2line
tools/../../bin/arm-linux-gnueabihf-ar
tools/../../bin/arm-linux-gnueabihf-as
tools/../../bin/arm-linux-gnueabihf-c++
tools/../../bin/arm-linux-gnueabihf-c++filt
tools/../../bin/arm-linux-gnueabihf-cpp
tools/../../bin/arm-linux-gnueabihf-ct-ng.config
tools/../../bin/arm-linux-gnueabihf-dwp
tools/../../bin/arm-linux-gnueabihf-elfedit
tools/../../bin/arm-linux-gnueabihf-g++
tools/../../bin/arm-linux-gnueabihf-gcc
tools/../../bin/arm-linux-gnueabihf-gcc-4.8.3
tools/../../bin/arm-linux-gnueabihf-gcc-ar
tools/../../bin/arm-linux-gnueabihf-gcc-nm
tools/../../bin/arm-linux-gnueabihf-gcc-ranlib
tools/../../bin/arm-linux-gnueabihf-gcov
tools/../../bin/arm-linux-gnueabihf-gdb
tools/../../bin/arm-linux-gnueabihf-gfortran
tools/../../bin/arm-linux-gnueabihf-gprof
tools/../../bin/arm-linux-gnueabihf-ld
tools/../../bin/arm-linux-gnueabihf-ld.bfd
tools/../../bin/arm-linux-gnueabihf-ldd
tools/../../bin/arm-linux-gnueabihf-ld.gold
tools/../../bin/arm-linux-gnueabihf-nm
tools/../../bin/arm-linux-gnueabihf-objcopy
tools/../../bin/arm-linux-gnueabihf-objdump
tools/../../bin/arm-linux-gnueabihf-pkg-config
tools/../../bin/arm-linux-gnueabihf-pkg-config-real
tools/../../bin/arm-linux-gnueabihf-ranlib
tools/../../bin/arm-linux-gnueabihf-readelf
tools/../../bin/arm-linux-gnueabihf-size
tools/../../bin/arm-linux-gnueabihf-strings
tools/../../bin/arm-linux-gnueabihf-strip

這邊我選用 gcc-linaro-arm-linux-gnueabihf-raspbian-x64 作為我待會要 cross compile 的 toolchain

Raspberry Pi Kernel (cross-compile + update)

λ ~/rasp/ git clone https://github.com/raspberrypi/linux --depth 1

進入資料夾後依序執行

1.先把建置環境清乾淨

λ ~/rasp/linux/ make mrproper

2.把機器上現有的 Kernel Config 倒出來 (在板子上執行)

# zcat /proc/config.gz > .config

然後再把這個 .config 檔案傳回 linux 資料夾底下

3.再來先設定好 CROSS_COMPILE 環境變數後，執行 make oldconfig

λ ~/rasp/linux/ export CROSS_COMPILE=~/rasp/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-
λ ~/rasp/linux/ ARCH=arm make oldconfig

PS1. 這邊 ARCH 記得要指定為 arm 不然會跑到你本機的架構 (ex: x86)
PS2. 執行 oldconfig 有可能會跳出一些選項要你選擇，是因為先前的 Kernel 沒有這些 options 新版本可能會有差異

4.最後執行 make

λ ~/rasp/linux/ ARCH=arm make

TicToc~TicToc 跑完後你就有全新的 Kernel 啦！

產出的檔案在 arch/arm/boot/Image

λ ~/rasp/linux/ ls arch/arm/boot/Image -alh
-rwxrwxr-x 1 zack zack 8.1M Apr 27 21:03 arch/arm/boot/Image

複製到機器上，/boot/kernel_new.img 然後修改 /boot/config.txt (怎麼會用附檔名 txt 呀好詭異 XDDD)，加入一行 kernel=kernel_new.img ，原本的 kernel 先改個名子放旁邊。

root@raspberrypi:/boot# cat config.txt
kernel=kernel_new.img

再來回到桌機這邊準備一下新的 Kernel modules

λ ~/rasp/ mkdir modules
λ ~/rasp/linux/ ARCH=arm INSTALL_MOD_PATH=~/rasp/modules make modules_install

新版本的 modules 就會跑到 ~/rasp/modules 囉，把它們全部 SCP 到板子上的 /lib 取代
(如果擔心玩壞可以先備份)

萬事搞定，直接下 Reboot 就可以看到裝著新的 Kernel 的 Raspberry Pi 啦~

root@raspberrypi:/boot# dmesg
[    0.000000] Booting Linux on physical CPU 0xf00
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
[    0.000000] Linux version 3.18.11-v7+ (zack@ubuntu) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.0
3) ) #1 SMP PREEMPT Mon Apr 27 21:03:05 CST 2015
[    0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c5387d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] Machine: BCM2709
[    0.000000] cma: Reserved 8 MiB at 0x3d800000
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] On node 0 totalpages: 253952
[    0.000000] free_area_init_node: node 0, pgdat 8080f480, node_mem_map bd033000
[    0.000000]   Normal zone: 1984 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 253952 pages, LIFO batch:31
[    0.000000] [bcm2709_smp_init_cpus] enter (8620->f3003010)
[    0.000000] [bcm2709_smp_init_cpus] ncores=4
[    0.000000] PERCPU: Embedded 10 pages/cpu @bd006000 s11456 r8192 d21312 u40960

參考資料