module

Author: jiaxianhua

_posts/2020-12-31-module.md

@@ -0,0 +1,209 @@
+---
+layout: post
+title: "LinuxLab 真板开发：开发内核模块"
+author: iosdevlog
+date: 2020-12-31 15:09:32 +0800
+description: ""
+cover-img: /assets/images/LinuxLab/IMX6ULL/hello_linux_lab_imx6ull.png
+category: 
+tags: [LinuxLab, IMX6ULL, module]
+---
+
+### 撰写并运行内核模块
+
+```bash
+mkdir -p src/modules/hello_imx6ull
+cd src/modules/hello_imx6ull
+vi hello_imx6ull.c
+```
+
+### hello_imx6ull.c
+
+```c
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+static int __init hello_imx6ull_init(void)
+{
+	pr_info("hello imx6ull module init\n");
+
+	return 0;
+}
+
+static void __exit hello_imx6ull_exit(void)
+{
+	pr_info("hello imx6ull module exit\n");
+}
+
+module_init(hello_imx6ull_init);
+module_exit(hello_imx6ull_exit);
+
+MODULE_DESCRIPTION("hello imx6ull - Linux Lab real board module example");
+MODULE_AUTHOR("iOSDevLog <iosdevlog@iosdevlog.com>");
+MODULE_LICENSE("GPL");
+```
+
+### Makefile
+
+```make
+# ARCH = arm
+# CROSS_COMPILE = arm-linux-gnueabi-
+
+KERNEL_SRC ?= /lib/modules/`uname -r`/build
+
+obj-m	+=   hello_imx6ull.o
+
+
+modules:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD modules;
+
+modules-install:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD modules-install;
+
+clean:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD clean;
+	$(RM) *.ko;
+```
+
+### 编译该内核模块
+
+```bash
+make modules m=hello_imx6ull
+make modules-install m=hello_imx6ull
+make modules-upload
+```
+
+### 在真板上启动内核模块
+
+```bash
+make login
+```
+
+登录 IMX6ULL。
+
+```bash
+sudo modprobe hello_imx6ull
+modprobe: ERROR: could not insert 'hello_imx6ull': Exec format error
+```
+
+原因未知。
+
+## `2021/01/04` 重头执行
+
+将 *预览版* 从 TF卡 [fire-config刷机](https://embed-linux-tutorial.readthedocs.io/zh_CN/latest/linux_basis/fire-config_brief.html) 到 emmc。
+
+重新执行了一遍 `next` 分支的操作。
+
+已经有了 `hello_imx6ull` 模块，这次新建一个 `hello_linux_lab_hello`。
+
+```bash
+cp -r src/modules/hello src/modules/hello_linux_lab_hello
+cd src/modules/hello_linux_lab_hello
+mv hello.c hello_linux_lab_hello.c
+```
+
+`hello_linux_lab_hello.c`
+
+```c
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+static int __init hello_linux_lab_imx6ull_init(void)
+{
+	pr_info("hello linux-lab imx6ull module init\n");
+
+	return 0;
+}
+
+static void __exit hello_linux_lab_imx6ull_exit(void)
+{
+	pr_info("hello linux-lab imx6ull module exit\n");
+}
+
+module_init(hello_linux_lab_imx6ull_init);
+module_exit(hello_linux_lab_imx6ull_exit);
+
+MODULE_DESCRIPTION("hello linux-lab imx6ull - Linux Lab real board module example");
+MODULE_AUTHOR("iOSDevLog <iosdevlog@iosdevlog.com>");
+MODULE_LICENSE("GPL");
+```
+
+`Makeifle`
+
+```make
+KERNEL_SRC ?= /lib/modules/`uname -r`/build
+
+obj-m	+=   hello_linux_lab_imx6ull.o
+
+
+modules:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD modules;
+
+modules-install:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD modules-install;
+
+clean:
+	$(MAKE) -C $(KERNEL_SRC) M=$$PWD clean;
+	rm -f *.ko;
+```
+
+Compile a kernel module and upload it
+
+```bash
+make modules m=hello_linux_lab_imx6ull
+make modules-install m=hello_linux_lab_imx6ull
+make modules-upload
+```
+
+验证
+
+```bash
+make login
+```
+
+查看 `hello_linux_lab_imx6ull.ko` 类型。
+
+```bash
+debian@npi:~$ ls /lib/modules/4.19.35+/extra/
+hello.ko  hello_imx6ull.ko  hello_linux_lab_imx6ull.ko
+sudo apt install file
+file /lib/modules/4.19.35+/extra/*
+```
+
+同 `hello.ko` 一样。
+
+```bash
+/lib/modules/4.19.35+/extra/hello.ko:                   ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=c669968dec7cfd12ff354756b21f4cb6653fc74b, with debug_info, not stripped
+/lib/modules/4.19.35+/extra/hello_imx6ull.ko:           ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=70f2771a81593d78ef1aea082b7bbf1ab54d6e11, with debug_info, not stripped
+/lib/modules/4.19.35+/extra/hello_linux_lab_imx6ull.ko: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=a72a2e20aa70392320fdcef88bb7844ae38a7c2c, with debug_info, not stripped
+```
+
+查看 `hello_linux_lab_imx6ull` 信息。
+
+```bash
+debian@npi:~$ sudo modprobe hello_linux_lab_imx6ull                            
+[ 1177.900660] hello linux-lab imx6ull module init                             
+debian@npi:~$ lsmod | grep hello_linux_lab_imx6ull                             
+hello_linux_lab_imx6ull    16384  0                                            
+debian@npi:~$ dmesg | grep "hello linux"                                       
+[ 1177.900660] hello linux-lab imx6ull module init                             
+debian@npi:~$ modinfo hello_linux_lab_imx6ull                                  
+filename:       /lib/modules/4.19.35+/extra/hello_linux_lab_imx6ull.ko         
+license:        GPL                                                            
+author:         iOSDevLog <iosdevlog@iosdevlog.com>                            
+description:    hello linux-lab imx6ull - Linux Lab real board module example  
+srcversion:     23F6F2563D3621635B131C2                                        
+depends:                                                                       
+name:           hello_linux_lab_imx6ull                                        
+vermagic:       4.19.35+ SMP preempt mod_unload modversions ARMv7 p2v8
+```
+
+![hello_linux_lab_imx6ull](/assets/images/LinuxLab/IMX6ULL/hello_linux_lab_imx6ull.png)
+
+## 总结
+
+年前不知什么原因，导致 `Exec format error` 错误，今天用干净的环境重新执行一下又可以了。
+
+确实要使用相同的环境（抽象出虚拟层）。