add post: openwrt kernel vermagic

source/_posts/openwrt-kernel-vermagic.md

@@ -0,0 +1,59 @@
+---
+title: OpenWrt 自行编译的内核扩展安装失败的解决方法
+date: 2021-08-20 16:53:07
+tags:
+---
+
+## 现象 ##
+拉取 `OpenWrt` 源码编译出来的内核扩展 `ipk` 拿到装有官方版本 `OpenWrt` 的路由器上无法安装，出现以下提示：
+```shell
+ * satisfy_dependencies_for: Cannot satisfy the following dependencies for kmod-xxx:
+ * 	kernel (= 4.14.241-1-68143adfcb7fc62a239c4be112fe40de)
+ * opkg_install_cmd: Cannot install package kmod-xxx.
+```
+
+## 解决方案 ##
+修改 `kernel vermagic` 从计算配置文件的 `md5 hash` 改为固定值。
+<!-- more -->
+
+* `OpenWrt` 源码根目录添加文件 `vermagic`
+```shell
+cat 68143adfcb7fc62a239c4be112fe40de ./vermagic
+```
+
+* 修改 `kernel-defaults.mk`
+```diff
+diff --git a/include/kernel-defaults.mk b/include/kernel-defaults.mk
+index cc1e2361be..35ffc1fbba 100644
+--- a/include/kernel-defaults.mk
++++ b/include/kernel-defaults.mk
+@@ -105,7 +105,7 @@ define Kernel/Configure/Default
+                cp $(LINUX_DIR)/.config.set $(LINUX_DIR)/.config.prev; \
+        }
+        $(_SINGLE) [ -d $(LINUX_DIR)/user_headers ] || $(KERNEL_MAKE) INSTALL_HDR_PATH=$(LINUX_DIR)/user_headers headers_install
+-       grep '=[ym]' $(LINUX_DIR)/.config.set | LC_ALL=C sort | mkhash md5 > $(LINUX_DIR)/.vermagic
++       cp $(TOPDIR)/vermagic $(LINUX_DIR)/.vermagic
+ endef
+```
+
+* 修改 `package/kernel/linux/Makefile`
+```diff
+diff --git a/package/kernel/linux/Makefile b/package/kernel/linux/Makefile
+index 39b9e82c27..6ff64b2939 100644
+--- a/package/kernel/linux/Makefile
++++ b/package/kernel/linux/Makefile
+@@ -24,7 +24,7 @@ export SHELL:=/bin/sh
+ include $(INCLUDE_DIR)/package.mk
+ 
+ ifeq ($(DUMP),)
+-  STAMP_BUILT:=$(STAMP_BUILT)_$(shell $(SCRIPT_DIR)/kconfig.pl $(LINUX_DIR)/.config | mkhash md5)
++  STAMP_BUILT:=$(STAMP_BUILT)_$(shell cat $(LINUX_DIR)/.vermagic)
+   -include $(LINUX_DIR)/.config
+ endif
+```
+
+## 重新编译 ##
+```shell
+$ make clean # 注意清除缓存
+$ make -j1 V=s
+```