OpenHarmony三方内核移植 原创

如下图所示，OpenHarmony 内核层主要包含OH Linux内核、OH内核态特性。其中OH Linux内核可以看成是由三方Linux内核+OH内核态基础代码的组成。

OH 默认Linux内核为5.10，为保证稳定性，移植OH时使用目标芯片的原生内核，在此基础上添加OH内核态基础代码、OH内核态特性。即，选择的移植方案是：OH 内核层 = 目标芯片的Linux 内核 + OH内核态基础代码 + HDF特性 ，以目标芯片Linux-4.19.15内核移植OH为例，移植过程如下：

0.首先准备内核源码

tar zxvf linux-4.19.15-860-oh.tar.gz  oh源码根目录/kernel/linux/linux-4.19.15

1 添加内核基础代码

# 0. 移植内核态基础代码 主要是hilog 和hievent，参考链接
https://docs.openharmony.cn/pages/v4.1/zh-cn/device-dev/porting/porting-linux-kernel.md/
   0.1 将以下文件，
         drivers/staging/hilog 
         drivers/staging/hievent
       从OpenHarmony内核代码目录kernel/linux/linux-4.19/drivers/staging中拷贝到kernel/linux/linux-4.19.15/drivers/staging中。
   0.2 在三方内核的linux-4.19.15/drivers/staging/Kconfig文件内增加如下代码：
        source "drivers/staging/hilog/Kconfig"
        source "drivers/staging/hievent/Kconfig"
   0.3 在在三方内核的linux-4.19.15/drivers/路径下的Makefile中添加配置
       obj-$(CONFIG_HILOG)             += hilog/
       obj-$(CONFIG_HIEVENT)           += hievent/
    
# 1. 内核config，拷贝内核根目录原来的.config文件到OH如下路径，并重命名target_small_defconfig.config
        kernel/linux/config/linux-4.19.15/arch/csky/configs/target_small_defconfig.config
        # 添加HDF选项，参考上面链接添加以下内容，
        # 参考kernel/linux/config/linux-4.19/arch/arm/configs/hispark_taurus_small_defconfig添加
        CONFIG_DRIVERS_HDF=y
        CONFIG_HDF_SUPPORT_LEVEL=1
        CONFIG_DRIVERS_HDF_PLATFORM=y
        # CONFIG_DRIVERS_HDF_PLATFORM_MIPI_DSI is not set
        # CONFIG_DRIVERS_HDF_PLATFORM_MIPI_CSI is not set
        CONFIG_DRIVERS_HDF_PLATFORM_GPIO=y
        CONFIG_DRIVERS_HDF_PLATFORM_I2C=y
        # CONFIG_DRIVERS_HDF_PLATFORM_WATCHDOG is not set
        CONFIG_DRIVERS_HDF_PLATFORM_PWM=y
        CONFIG_DRIVERS_HDF_PLATFORM_UART=y
        # CONFIG_DRIVERS_HDF_PLATFORM_SDIO is not set
        # CONFIG_DRIVERS_HDF_PLATFORM_EMMC is not set
        CONFIG_DRIVERS_HDF_PLATFORM_MMC=y
        CONFIG_DRIVERS_HDF_PLATFORM_SPI=y
        CONFIG_DRIVERS_HDF_PLATFORM_RTC=y
        # CONFIG_PWM_HI35XX is not set
        # CONFIG_DRIVERS_HDF_PLATFORM_REGULATOR is not set
        CONFIG_DRIVERS_HDF_PLATFORM_ADC=y
        # CONFIG_DRIVERS_HDF_PLATFORM_TRACE is not set
        # CONFIG_DRIVERS_HDF_PLATFORM_DUMPER is not set
        # CONFIG_IMX8MM_EMMC is not set
        # CONFIG_IMX8MM_SDIO is not set
        # CONFIG_DRIVERS_HDF_PLATFORM_IMX8MM_MIPI_DSI is not set
        CONFIG_DRIVERS_HDF_TEST=y
        # CONFIG_IMX8MM_SPI_TEST is not set
        # CONFIG_DRIVERS_HDF_DISP is not set
        # CONFIG_DRIVERS_HDF_INPUT is not set
        # CONFIG_DRIVERS_HDF_NETDEV_EXT is not set
        # CONFIG_DRIVERS_HDF_BT is not set
        # CONFIG_DRIVERS_HDF_SENSOR is not set
        # CONFIG_DRIVERS_HDF_STORAGE is not set
        # CONFIG_IMX8MM_SDIO_TEST is not set
        # CONFIG_DRIVERS_HDF_USB_PNP_NOTIFY is not set
        # CONFIG_DRIVERS_HDF_AUDIO is not set
        # CONFIG_DRIVERS_HDF_VIBRATOR is not set
        # CONFIG_DRIVERS_HDF_DSOFTBUS is not set
        # CONFIG_DRIVERS_HDF_LIGHT is not set
        # CONFIG_DRIVERS_HDF_NETWORK is not set

2 打hdf补丁

如果不添加HDF补丁，编译会报错遇到 undefined reference to _hdf_drivers_end' 、 undefined reference to _hdf_drivers_start’

**检查内核补丁，**发现是因为执行drivers/hdf_core/adapter/khdf/linux/patch_hdf.sh时，默认添加的补丁路径和内容为：

kernel/linux/patches/linux-4.19/common_patch/hdf.patch
// 部分内容如下：
    //-----------------------------针对arm64架构的hdf补丁--------------------------------
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 69e7c8d4a..6bdc118dd 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S  //
@@ -176,6 +176,15 @@ SECTIONS
 		INIT_RAM_FS
 		*(.init.rodata.* .init.bss)	/* from the EFI stub */
 	}
+
+#ifdef CONFIG_DRIVERS_HDF
+	.init.hdf_table : {
+		_hdf_drivers_start = .;
+		*(.hdf.driver)
+		_hdf_drivers_end = .;
+	}
+#endif
+
 	.exit.data : {
 		ARM_EXIT_KEEP(EXIT_DATA)
 	}
// --------------------------------针对arm架构的hdf补丁----------------------------------
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 23150c0f0..2780470c5 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -121,6 +121,14 @@ SECTIONS
 		__pv_table_end = .;
 	}
 
+#ifdef CONFIG_DRIVERS_HDF
+	.init.hdf_table : {
+		_hdf_drivers_start = .;
+		*(.hdf.driver)
+		_hdf_drivers_end = .;
+	}
+#endif
+
 	INIT_DATA_SECTION(16)
//--------------------------------如果目标芯片架构比较新，需要补充目标芯片如csky架构的hdf补丁------------------------------

hi3516是arm架构的，而新的csky架构，所以这个默认common_patch/hdf.patch补丁打到了arch/arm中，两种解决方法：

• 1.在 kernel/linux/patches/linux-4.19/common_patch/hdf.patch中添加针对csky的补丁，

• 2.直接修改/kernel/src_tmp/linux-4.19.15/arch/csky/kernel/vmlinux.lds.S，添加hdf占位符代码：

// 32行开始添加如下代码	
#ifdef CONFIG_DRIVERS_HDF
	.init.hdf_table : {
		_hdf_drivers_start = .;
		*(.hdf.driver)
		_hdf_drivers_end = .;
	}

方法1需要制作补丁文件，因为需要找到目标芯片的linux内核、OH内核提交hdf补丁的pr，因为难以寻找，故选择方法2，手动添加

# 2. 内核补丁  
       2.1 手动添加HDF补丁，直接修改//kernel/linux/linux-4.19.15/arch/csky/kernel/vmlinux.lds.S，添加代码：
        # 32行开始添加如下代码	
        #ifdef CONFIG_DRIVERS_HDF
            .init.hdf_table : {
                _hdf_drivers_start = .;
                *(.hdf.driver)
                _hdf_drivers_end = .;
            }