19 内核开发-内核源码编译

(1)开始准备

安装好virtual box + ubuntu 系统后，即可下载内核代码，进行编译

历史内核源码地址：https://mirrors.tuna.tsinghua.edu.cn/kernel/v5.x/
下载 linux-5.10.102.tar.gz 的包,可以使用wget 命令
创建编译目录 /home/peach/lkd_kernels/productionk
然后解压到磁盘上 /home/peach/lkd_kernels/productionk
tar -zxf linux-5.10.102.tar.gz --directory=/home/peach/lkd_kernels/productionk/

(2)安装必备编译软件

sudo apt update 
sudo apt upgrade 
sudo apt install build-essential dkms ssh -y
sudo apt install linux-headers-$(uname –r) ssh -y

(3)进行kernel config 配置

lsmod > /tmp/lsmod.now
make LSMOD=/tmp/lsmod.now localmodconfig

# 备份执行文件：
cp –af .config ~/lkd_kernels/kconfig_prod01

# 执行编译
make -j8

我们已经看到生成了我们需要文件 bzImage和vmlinux 文件。

注意：make LSMOD=/tmp/lsmod.now localmodconfig 该命令将执行以下操作。

设置环境变量 LSMOD 为 /tmp/lsmod.now。
执行 localmodconfig 目标。
localmodconfig 目标通常用于配置内核模块，它将创建一个名为 .config 的文件，其中包含用于编译内核模块的配置选项。
因此，该命令将使用 /tmp/lsmod.now 文件中的选项配置内核模块，然后编译该模块。
请注意，/tmp/lsmod.now 文件必须存在并且包含有效的内核模块配置选项。

(4)遇到错误

错误：一些包没有安装

make[1]: *** No rule to make target 'debian/canonical-certs.pem', needed by 'certs/x509_certificate_list'. Stop.
make: *** [Makefile:1868: certs] Error 2

#解决
scripts/config --disable SYSTEM_TRUSTED_KEYS

错误：
make[1]: *** No rule to make target 'debian/canonical-revoked-certs.pem', needed by 'certs/x509_revocation_list'. Stop.
make: *** [Makefile:1868: certs] Error 2

#解决
scripts/config --disable SYSTEM_REVOCATION_KEYS

报错：
BTF: .tmp_vmlinux.btf: pahole (pahole) is not available
Failed to generate BTF for vmlinux
Try to disable CONFIG_DEBUG_INFO_BTF
make: *** [Makefile:1161: vmlinux] Error 1

一般是系统缺少dwarves软件包导致。

#解决
sudo apt-get install dwarves

报错：

FAILED: load BTF from vmlinux: Unknown error -2make: *** [Makefile:1179: vmlinux] Error 255

排查
peach@peach:~/lkd_kernels/productionk/linux-5.10.102$ sudo dmesg | grep pahole

[ 3353.221446] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/user.slice/user-1000.slice/session-6.scope,task=pahole,pid=92508,uid=1000
[ 3353.221459] Out of memory: Killed process 92508 (pahole) total-vm:2031180kB, anon-rss:1651324kB, file-rss:4kB, shmem-rss:0kB, UID:1000 pgtables:4036kB oom_score_adj:0
[ 3565.138510] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/user.slice/user-1000.slice/session-6.scope,task=pahole,pid=97364,uid=1000
[ 3565.138525] Out of memory: Killed process 97364 (pahole) total-vm:2031180kB, anon-rss:1647620kB, file-rss:4kB, shmem-rss:0kB, UID:1000 pgtables:4040kB oom_score_adj:0
[ 3714.551892] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),cpuset=/,mems_allowed=0,global_oom,task_memcg=/user.slice/user-1000.slice/session-6.scope,task=pahole,pid=102077,uid=1000
[ 3714.551907] Out of memory: Killed process 102077 (pahole) total-vm:2031180kB, anon-rss:1665776kB, file-rss:4kB, shmem-rss:0kB, UID:1000 pgtables:4032kB oom_score_adj:0

有人说要 10g 内存, 我的版本时 5.10 的，我分配了8g 就编译通过了，其实没有那么夸张。

Just quick FYI: Current linux build needs at least 10GB of RAM!

I was just trying to build kernel 6.5 and noticed the process was being killed after both SWAP+RAM was getting full. I started with 4.0 of RAM on my VM, then increased until it passed.

I noticed the linux building process needing about 10GiB of RAM to finish building without throwing that error. This is crazy on how much RAM it needs.

内存不够 oom killed了

# 调大虚拟机的内存该为8g