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开发板 ：NanoPC-T4开发板eMMC ：16GBLPDDR3 ：4GB显示屏 ：15.6英寸HDMI接口显示屏u-boot ：Rockchip官方uboot 2017.09linux ：5.2.8----------------------------------------------------------------------------------------------------------------------------
在前面的章节，我们已经介绍了在RK3399上面移植Rockchip官方提供的uboot 2017.09，这一节我们将移植linux 5.2.8到RK3399上。
一、linux内核
像uboot一样，linux内核通常有三种：
- linux官方源码：https://github.com/torvalds/linux，linux官方源码是由linux官方维护，支持非常全面的芯片，但对具体某款开发板支持情况一般；
- 半导体厂商瑞芯微官方源码：https://github.com/rockchip-linux/kernel，半导体厂商基于linux官方源码进行修改，对自家的芯片进行完善的支持，针对某款处理器支持情况较好；
- 开发板友善之家官方源码：https://github.com/friendlyarm/kernel-rockchip，开发板厂商基于半导体厂商维护的linux，对自家的开发板进行板级支持，针对某款开发板支持情况较好；
由于Rockchip官方提供的内核版本较低，所以这里我们直接去linux官方去下载，然后后面参考开发板友善之家官方源码修改使其能够支持NanoPC-T4开发板。
1.1 源码下载
内核源码下载地址为：https://www.kernel.org/，这里我们不下载最新的6.3.2版本，我们和之前介绍的Mini2440内核移植一样，选择5.2.8版本：
也可以到内核镜像网址下载https://mirrors.edge.kernel.org/pub/linux/kernel/，这里下载速度更快。
如果下载速度太慢，无法下载，提供另一个链接：http://ftp.sjtu.edu.cn/sites/ftp.kernel.org/pub/linux/kernel/。
我们这里下载linux-5.2.8版本，执行如下命令：
root@zhengyang:/work/sambashare/rk3399# wget http://ftp.sjtu.edu.cn/sites/ftp.kernel.org/pub/linux/kernel/v5.x/linux-5.2.8.tar.gz
这里我是下载到/work/sambashare/rk3399路径下的，这个路径是用来专门存放与rk3399相关的内容。
解压源码：
root@zhengyang:/work/sambashare/rk3399# tar -xvf linux-5.2.8.tar.gz
关于linux内核的目录结构我们之前已经介绍过，这里就不再重复叙述了。
root@zhengyang:/work/sambashare/rk3399# cd linux-5.2.8/
root@zhengyang:/work/sambashare/rk3399/linux-5.2.8# ll
总用量 840
drwxrwxr-x 24 root root 4096 Aug 9 2019 ./
drwxr-xr-x 8 root root 4096 May 17 04:16 ../
drwxrwxr-x 27 root root 4096 Aug 9 2019 arch/
drwxrwxr-x 3 root root 4096 Aug 9 2019 block/
drwxrwxr-x 2 root root 4096 Aug 9 2019 certs/
-rw-rw-r-- 1 root root 14943 Aug 9 2019 .clang-format
-rw-rw-r-- 1 root root 59 Aug 9 2019 .cocciconfig
-rw-rw-r-- 1 root root 423 Aug 9 2019 COPYING
-rw-rw-r-- 1 root root 99486 Aug 9 2019 CREDITS
drwxrwxr-x 4 root root 4096 Aug 9 2019 crypto/
drwxrwxr-x 122 root root 12288 Aug 9 2019 Documentation/
drwxrwxr-x 140 root root 4096 Aug 9 2019 drivers/
drwxrwxr-x 73 root root 4096 Aug 9 2019 fs/
-rw-rw-r-- 1 root root 71 Aug 9 2019 .get_maintainer.ignore
-rw-rw-r-- 1 root root 30 Aug 9 2019 .gitattributes
-rw-rw-r-- 1 root root 1658 Aug 9 2019 .gitignore
drwxrwxr-x 27 root root 4096 Aug 9 2019 include/
drwxrwxr-x 2 root root 4096 Aug 9 2019 init/
drwxrwxr-x 2 root root 4096 Aug 9 2019 ipc/
-rw-rw-r-- 1 root root 1513 Aug 9 2019 Kbuild
-rw-rw-r-- 1 root root 563 Aug 9 2019 Kconfig
drwxrwxr-x 18 root root 4096 Aug 9 2019 kernel/
drwxrwxr-x 15 root root 12288 Aug 9 2019 lib/
drwxrwxr-x 6 root root 4096 Aug 9 2019 LICENSES/
-rw-rw-r-- 1 root root 12316 Aug 9 2019 .mailmap
-rw-rw-r-- 1 root root 512407 Aug 9 2019 MAINTAINERS
-rw-rw-r-- 1 root root 60262 Aug 9 2019 Makefile
drwxrwxr-x 3 root root 4096 Aug 9 2019 mm/
drwxrwxr-x 70 root root 4096 Aug 9 2019 net/
-rw-rw-r-- 1 root root 727 Aug 9 2019 README
drwxrwxr-x 29 root root 4096 Aug 9 2019 samples/
drwxrwxr-x 15 root root 4096 Aug 9 2019 scripts/
drwxrwxr-x 11 root root 4096 Aug 9 2019 security/
drwxrwxr-x 26 root root 4096 Aug 9 2019 sound/
drwxrwxr-x 36 root root 4096 Aug 9 2019 tools/
drwxrwxr-x 2 root root 4096 Aug 9 2019 usr/
drwxrwxr-x 4 root root 4096 Aug 9 2019 virt/
1.2 配置Makefile
修改顶层的 Makefile，打开 Makefile 文件，找到下面语句：
ARCH ?= $(SUBARCH)
修改为：
ARCH ?= arm64
CROSS_COMPILE ?= arm-linux-
其中，ARCH 是指定目标平台为arm64，CROSS_COMPILE是指定交叉编译器，这里指定的是系统默认的交叉编译器，如要使用其它的，则要把编译器的全路径在这里写出。
1.3 内核defconfig配置
接下来要做的就是内核配置、编译了。单板的默认配置文件在arch/arm64/configs目录下：
root@zhengyang:/work/sambashare/rk3399/linux-5.2.8# ll arch/arm64/configs/defconfig
-rw-rw-r-- 1 root root 18417 Aug 9 2019 arch/arm64/configs/defconfig
在这个目录下就这一个配置，我们也没有其它选择了，那只能走一步看一步了。
配置文件defconfig其定义如下：
CONFIG_SYSVIPC=y
CONFIG_POSIX_MQUEUE=y
CONFIG_AUDIT=y
CONFIG_NO_HZ_IDLE=y
CONFIG_HIGH_RES_TIMERS=y
CONFIG_PREEMPT=y
CONFIG_IRQ_TIME_ACCOUNTING=y
CONFIG_BSD_PROCESS_ACCT=y
CONFIG_BSD_PROCESS_ACCT_V3=y
CONFIG_TASKSTATS=y
CONFIG_TASK_DELAY_ACCT=y
CONFIG_TASK_XACCT=y
CONFIG_TASK_IO_ACCOUNTING=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
CONFIG_NUMA_BALANCING=y
CONFIG_MEMCG=y
CONFIG_MEMCG_SWAP=y
CONFIG_BLK_CGROUP=y
CONFIG_CGROUP_PIDS=y
CONFIG_CGROUP_HUGETLB=y
CONFIG_CPUSETS=y
CONFIG_CGROUP_DEVICE=y
CONFIG_CGROUP_CPUACCT=y
CONFIG_CGROUP_PERF=y
CONFIG_USER_NS=y
CONFIG_SCHED_AUTOGROUP=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_KALLSYMS_ALL=y
# CONFIG_COMPAT_BRK is not set
CONFIG_PROFILING=y
CONFIG_ARCH_AGILEX=y
CONFIG_ARCH_SUNXI=y
CONFIG_ARCH_ALPINE=y
CONFIG_ARCH_BCM2835=y
CONFIG_ARCH_BCM_IPROC=y
CONFIG_ARCH_BERLIN=y
CONFIG_ARCH_BRCMSTB=y
CONFIG_ARCH_EXYNOS=y
CONFIG_ARCH_K3=y
CONFIG_ARCH_LAYERSCAPE=y
CONFIG_ARCH_LG1K=y
CONFIG_ARCH_HISI=y
CONFIG_ARCH_MEDIATEK=y
CONFIG_ARCH_MESON=y
CONFIG_ARCH_MVEBU=y
CONFIG_ARCH_MXC=y
CONFIG_ARCH_QCOM=y
CONFIG_ARCH_RENESAS=y
CONFIG_ARCH_ROCKCHIP=y
CONFIG_ARCH_SEATTLE=y
CONFIG_ARCH_STRATIX10=y
CONFIG_ARCH_SYNQUACER=y
CONFIG_ARCH_TEGRA=y
CONFIG_ARCH_SPRD=y
CONFIG_ARCH_THUNDER=y
CONFIG_ARCH_THUNDER2=y
CONFIG_ARCH_UNIPHIER=y
CONFIG_ARCH_VEXPRESS=y
CONFIG_ARCH_XGENE=y
CONFIG_ARCH_ZX=y
CONFIG_ARCH_ZYNQMP=y
CONFIG_ARM64_VA_BITS_48=y
CONFIG_SCHED_MC=y
CONFIG_NUMA=y
CONFIG_SECCOMP=y
CONFIG_KEXEC=y
CONFIG_CRASH_DUMP=y
CONFIG_XEN=y
CONFIG_COMPAT=y
CONFIG_HIBERNATION=y
CONFIG_WQ_POWER_EFFICIENT_DEFAULT=y
CONFIG_ARM_CPUIDLE=y
CONFIG_CPU_FREQ=y
CONFIG_CPU_FREQ_STAT=y
CONFIG_CPU_FREQ_GOV_POWERSAVE=m
CONFIG_CPU_FREQ_GOV_USERSPACE=y
CONFIG_CPU_FREQ_GOV_ONDEMAND=y
CONFIG_CPU_FREQ_GOV_CONSERVATIVE=m
CONFIG_CPU_FREQ_GOV_SCHEDUTIL=y
CONFIG_CPUFREQ_DT=y
CONFIG_ACPI_CPPC_CPUFREQ=m
CONFIG_ARM_ARMADA_37XX_CPUFREQ=y
CONFIG_ARM_SCPI_CPUFREQ=y
CONFIG_ARM_TEGRA186_CPUFREQ=y
CONFIG_ARM_SCPI_PROTOCOL=y
CONFIG_RASPBERRYPI_FIRMWARE=y
CONFIG_INTEL_STRATIX10_SERVICE=y
CONFIG_TI_SCI_PROTOCOL=y
CONFIG_EFI_CAPSULE_LOADER=y
CONFIG_IMX_SCU=y
CONFIG_IMX_SCU_PD=y
CONFIG_ACPI=y
CONFIG_ACPI_APEI=y
CONFIG_ACPI_APEI_GHES=y
CONFIG_ACPI_APEI_MEMORY_FAILURE=y
CONFIG_ACPI_APEI_EINJ=y
CONFIG_VIRTUALIZATION=y
CONFIG_KVM=y
CONFIG_ARM64_CRYPTO=y
CONFIG_CRYPTO_SHA1_ARM64_CE=y
CONFIG_CRYPTO_SHA2_ARM64_CE=y
CONFIG_CRYPTO_SHA512_ARM64_CE=m
CONFIG_CRYPTO_SHA3_ARM64=m
CONFIG_CRYPTO_SM3_ARM64_CE=m
CONFIG_CRYPTO_GHASH_ARM64_CE=y
CONFIG_CRYPTO_CRCT10DIF_ARM64_CE=m
CONFIG_CRYPTO_AES_ARM64_CE_CCM=y
CONFIG_CRYPTO_AES_ARM64_CE_BLK=y
CONFIG_CRYPTO_CHACHA20_NEON=m
CONFIG_CRYPTO_AES_ARM64_BS=m
CONFIG_JUMP_LABEL=y
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
# CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
CONFIG_KSM=y
CONFIG_MEMORY_FAILURE=y
CONFIG_TRANSPARENT_HUGEPAGE=y
CONFIG_CMA=y
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_UNIX=y
CONFIG_INET=y
CONFIG_IP_MULTICAST=y
CONFIG_IP_PNP=y
CONFIG_IP_PNP_DHCP=y
CONFIG_IP_PNP_BOOTP=y
CONFIG_IPV6=m
CONFIG_NETFILTER=y
CONFIG_NF_CONNTRACK=m
CONFIG_NF_CONNTRACK_EVENTS=y
CONFIG_NETFILTER_XT_TARGET_CHECKSUM=m
CONFIG_NETFILTER_XT_TARGET_LOG=m
CONFIG_NETFILTER_XT_MATCH_ADDRTYPE=m
CONFIG_NETFILTER_XT_MATCH_CONNTRACK=m
CONFIG_IP_NF_IPTABLES=m
CONFIG_IP_NF_FILTER=m
CONFIG_IP_NF_TARGET_REJECT=m
CONFIG_IP_NF_NAT=m
CONFIG_IP_NF_TARGET_MASQUERADE=m
CONFIG_IP_NF_MANGLE=m
CONFIG_IP6_NF_IPTABLES=m
CONFIG_IP6_NF_FILTER=m
CONFIG_IP6_NF_TARGET_REJECT=m
CONFIG_IP6_NF_MANGLE=m
CONFIG_IP6_NF_NAT=m
CONFIG_IP6_NF_TARGET_MASQUERADE=m
CONFIG_BRIDGE=m
CONFIG_BRIDGE_VLAN_FILTERING=y
CONFIG_VLAN_8021Q=m
CONFIG_VLAN_8021Q_GVRP=y
CONFIG_VLAN_8021Q_MVRP=y
CONFIG_QRTR=m
CONFIG_QRTR_SMD=m
CONFIG_QRTR_TUN=m
CONFIG_BPF_JIT=y
CONFIG_BT=m
CONFIG_BT_HIDP=m
# CONFIG_BT_HS is not set
# CONFIG_BT_LE is not set
CONFIG_BT_LEDS=y
# CONFIG_BT_DEBUGFS is not set
CONFIG_BT_HCIBTUSB=m
CONFIG_BT_HCIUART=m
CONFIG_BT_HCIUART_LL=y
CONFIG_BT_HCIUART_BCM=y
CONFIG_CFG80211=m
CONFIG_MAC80211=m
CONFIG_MAC80211_LEDS=y
CONFIG_RFKILL=m
CONFIG_NET_9P=y
CONFIG_NET_9P_VIRTIO=y
CONFIG_PCI=y
CONFIG_PCIEPORTBUS=y
CONFIG_PCI_IOV=y
CONFIG_HOTPLUG_PCI=y
CONFIG_HOTPLUG_PCI_ACPI=y
CONFIG_PCI_AARDVARK=y
CONFIG_PCI_TEGRA=y
CONFIG_PCIE_RCAR=y
CONFIG_PCI_HOST_GENERIC=y
CONFIG_PCI_XGENE=y
CONFIG_PCIE_ALTERA=y
CONFIG_PCIE_ALTERA_MSI=y
CONFIG_PCI_HOST_THUNDER_PEM=y
CONFIG_PCI_HOST_THUNDER_ECAM=y
CONFIG_PCIE_ROCKCHIP_HOST=m
CONFIG_PCI_LAYERSCAPE=y
CONFIG_PCI_HISI=y
CONFIG_PCIE_QCOM=y
CONFIG_PCIE_ARMADA_8K=y
CONFIG_PCIE_KIRIN=y
CONFIG_PCIE_HISI_STB=y
CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_HISILICON_LPC=y
CONFIG_SIMPLE_PM_BUS=y
CONFIG_MTD=y
CONFIG_MTD_BLOCK=y
CONFIG_MTD_M25P80=y
CONFIG_MTD_RAW_NAND=y
CONFIG_MTD_NAND_DENALI_DT=y
CONFIG_MTD_NAND_MARVELL=y
CONFIG_MTD_NAND_QCOM=y
CONFIG_MTD_SPI_NOR=y
CONFIG_BLK_DEV_LOOP=y
CONFIG_BLK_DEV_NBD=m
CONFIG_VIRTIO_BLK=y
CONFIG_BLK_DEV_NVME=m
CONFIG_SRAM=y
CONFIG_EEPROM_AT25=m
# CONFIG_SCSI_PROC_FS is not set
CONFIG_BLK_DEV_SD=y
CONFIG_SCSI_SAS_ATA=y
CONFIG_SCSI_HISI_SAS=y
CONFIG_SCSI_HISI_SAS_PCI=y
CONFIG_SCSI_UFSHCD=y
CONFIG_SCSI_UFSHCD_PLATFORM=y
CONFIG_SCSI_UFS_QCOM=m
CONFIG_SCSI_UFS_HISI=y
CONFIG_ATA=y
CONFIG_SATA_AHCI=y
CONFIG_SATA_AHCI_PLATFORM=y
CONFIG_AHCI_CEVA=y
CONFIG_AHCI_MVEBU=y
CONFIG_AHCI_XGENE=y
CONFIG_AHCI_QORIQ=y
CONFIG_SATA_SIL24=y
CONFIG_SATA_RCAR=y
CONFIG_PATA_PLATFORM=y
CONFIG_PATA_OF_PLATFORM=y
CONFIG_NETDEVICES=y
CONFIG_MACVLAN=m
CONFIG_MACVTAP=m
CONFIG_TUN=y
CONFIG_VETH=m
CONFIG_VIRTIO_NET=y
CONFIG_AMD_XGBE=y
CONFIG_NET_XGENE=y
CONFIG_ATL1C=m
CONFIG_MACB=y
CONFIG_THUNDER_NIC_PF=y
CONFIG_FEC=y
CONFIG_HIX5HD2_GMAC=y
CONFIG_HNS_DSAF=y
CONFIG_HNS_ENET=y
CONFIG_HNS3=y
CONFIG_HNS3_HCLGE=y
CONFIG_HNS3_ENET=y
CONFIG_E1000E=y
CONFIG_IGB=y
CONFIG_IGBVF=y
CONFIG_MVNETA=y
CONFIG_MVPP2=y
CONFIG_SKY2=y
CONFIG_QCOM_EMAC=m
CONFIG_RAVB=y
CONFIG_SMC91X=y
CONFIG_SMSC911X=y
CONFIG_SNI_AVE=y
CONFIG_SNI_NETSEC=y
CONFIG_STMMAC_ETH=m
CONFIG_MDIO_BUS_MUX_MMIOREG=y
CONFIG_AT803X_PHY=m
CONFIG_MARVELL_PHY=m
CONFIG_MARVELL_10G_PHY=m
CONFIG_MESON_GXL_PHY=m
CONFIG_MICREL_PHY=y
CONFIG_REALTEK_PHY=m
CONFIG_ROCKCHIP_PHY=y
CONFIG_USB_PEGASUS=m
CONFIG_USB_RTL8150=m
CONFIG_USB_RTL8152=m
CONFIG_USB_LAN78XX=m
CONFIG_USB_USBNET=m
CONFIG_USB_NET_DM9601=m
CONFIG_USB_NET_SR9800=m
CONFIG_USB_NET_SMSC75XX=m
CONFIG_USB_NET_SMSC95XX=m
CONFIG_USB_NET_PLUSB=m
CONFIG_USB_NET_MCS7830=m
CONFIG_ATH10K=m
CONFIG_ATH10K_PCI=m
CONFIG_BRCMFMAC=m
CONFIG_MWIFIEX=m
CONFIG_MWIFIEX_PCIE=m
CONFIG_WL18XX=m
CONFIG_WLCORE_SDIO=m
CONFIG_INPUT_EVDEV=y
CONFIG_KEYBOARD_ADC=m
CONFIG_KEYBOARD_GPIO=y
CONFIG_KEYBOARD_CROS_EC=y
CONFIG_INPUT_TOUCHSCREEN=y
CONFIG_TOUCHSCREEN_ATMEL_MXT=m
CONFIG_INPUT_MISC=y
CONFIG_INPUT_PM8941_PWRKEY=y
CONFIG_INPUT_HISI_POWERKEY=y
# CONFIG_SERIO_SERPORT is not set
CONFIG_SERIO_AMBAKMI=y
CONFIG_LEGACY_PTY_COUNT=16
CONFIG_SERIAL_8250=y
CONFIG_SERIAL_8250_CONSOLE=y
CONFIG_SERIAL_8250_EXTENDED=y
CONFIG_SERIAL_8250_SHARE_IRQ=y
CONFIG_SERIAL_8250_BCM2835AUX=y
CONFIG_SERIAL_8250_DW=y
CONFIG_SERIAL_8250_OMAP=y
CONFIG_SERIAL_8250_MT6577=y
CONFIG_SERIAL_8250_UNIPHIER=y
CONFIG_SERIAL_OF_PLATFORM=y
CONFIG_SERIAL_AMBA_PL011=y
CONFIG_SERIAL_AMBA_PL011_CONSOLE=y
CONFIG_SERIAL_MESON=y
CONFIG_SERIAL_MESON_CONSOLE=y
CONFIG_SERIAL_SAMSUNG=y
CONFIG_SERIAL_SAMSUNG_CONSOLE=y
CONFIG_SERIAL_TEGRA=y
CONFIG_SERIAL_TEGRA_TCU=y
CONFIG_SERIAL_IMX=y
CONFIG_SERIAL_IMX_CONSOLE=y
CONFIG_SERIAL_SH_SCI=y
CONFIG_SERIAL_MSM=y
CONFIG_SERIAL_MSM_CONSOLE=y
CONFIG_SERIAL_QCOM_GENI=y
CONFIG_SERIAL_QCOM_GENI_CONSOLE=y
CONFIG_SERIAL_XILINX_PS_UART=y
CONFIG_SERIAL_XILINX_PS_UART_CONSOLE=y
CONFIG_SERIAL_FSL_LPUART=y
CONFIG_SERIAL_FSL_LPUART_CONSOLE=y
CONFIG_SERIAL_MVEBU_UART=y
CONFIG_SERIAL_DEV_BUS=y
CONFIG_VIRTIO_CONSOLE=y
CONFIG_IPMI_HANDLER=m
CONFIG_IPMI_DEVICE_INTERFACE=m
CONFIG_IPMI_SI=m
CONFIG_TCG_TPM=y
CONFIG_TCG_TIS_I2C_INFINEON=y
CONFIG_I2C_CHARDEV=y
CONFIG_I2C_MUX=y
CONFIG_I2C_MUX_PCA954x=y
CONFIG_I2C_BCM2835=m
CONFIG_I2C_DESIGNWARE_PLATFORM=y
CONFIG_I2C_GPIO=m
CONFIG_I2C_IMX=y
CONFIG_I2C_MESON=y
CONFIG_I2C_MV64XXX=y
CONFIG_I2C_PXA=y
CONFIG_I2C_QUP=y
CONFIG_I2C_RK3X=y
CONFIG_I2C_SH_MOBILE=y
CONFIG_I2C_TEGRA=y
CONFIG_I2C_UNIPHIER_F=y
CONFIG_I2C_RCAR=y
CONFIG_I2C_CROS_EC_TUNNEL=y
CONFIG_SPI=y
CONFIG_SPI_ARMADA_3700=y
CONFIG_SPI_BCM2835=m
CONFIG_SPI_BCM2835AUX=m
CONFIG_SPI_NXP_FLEXSPI=y
CONFIG_SPI_MESON_SPICC=m
CONFIG_SPI_MESON_SPIFC=m
CONFIG_SPI_ORION=y
CONFIG_SPI_PL022=y
CONFIG_SPI_ROCKCHIP=y
CONFIG_SPI_QUP=y
CONFIG_SPI_S3C64XX=y
CONFIG_SPI_SPIDEV=m
CONFIG_SPI_SUN6I=y
CONFIG_SPMI=y
CONFIG_PINCTRL_SINGLE=y
CONFIG_PINCTRL_MAX77620=y
CONFIG_PINCTRL_IMX8MQ=y
CONFIG_PINCTRL_IMX8QXP=y
CONFIG_PINCTRL_IPQ8074=y
CONFIG_PINCTRL_MSM8916=y
CONFIG_PINCTRL_MSM8994=y
CONFIG_PINCTRL_MSM8996=y
CONFIG_PINCTRL_MSM8998=y
CONFIG_PINCTRL_QCS404=y
CONFIG_PINCTRL_QDF2XXX=y
CONFIG_PINCTRL_QCOM_SPMI_PMIC=y
CONFIG_PINCTRL_SDM845=y
CONFIG_GPIO_DWAPB=y
CONFIG_GPIO_MB86S7X=y
CONFIG_GPIO_PL061=y
CONFIG_GPIO_RCAR=y
CONFIG_GPIO_UNIPHIER=y
CONFIG_GPIO_XGENE=y
CONFIG_GPIO_XGENE_SB=y
CONFIG_GPIO_PCA953X=y
CONFIG_GPIO_PCA953X_IRQ=y
CONFIG_GPIO_MAX77620=y
CONFIG_POWER_AVS=y
CONFIG_ROCKCHIP_IODOMAIN=y
CONFIG_POWER_RESET_MSM=y
CONFIG_POWER_RESET_XGENE=y
CONFIG_POWER_RESET_SYSCON=y
CONFIG_SYSCON_REBOOT_MODE=y
CONFIG_BATTERY_SBS=m
CONFIG_BATTERY_BQ27XXX=y
CONFIG_SENSORS_ARM_SCPI=y
CONFIG_SENSORS_LM90=m
CONFIG_SENSORS_PWM_FAN=m
CONFIG_SENSORS_RASPBERRYPI_HWMON=m
CONFIG_SENSORS_INA2XX=m
CONFIG_THERMAL_GOV_POWER_ALLOCATOR=y
CONFIG_CPU_THERMAL=y
CONFIG_THERMAL_EMULATION=y
CONFIG_ROCKCHIP_THERMAL=m
CONFIG_RCAR_THERMAL=y
CONFIG_RCAR_GEN3_THERMAL=y
CONFIG_ARMADA_THERMAL=y
CONFIG_BCM2835_THERMAL=m
CONFIG_BRCMSTB_THERMAL=m
CONFIG_EXYNOS_THERMAL=y
CONFIG_TEGRA_BPMP_THERMAL=m
CONFIG_QCOM_TSENS=y
CONFIG_UNIPHIER_THERMAL=y
CONFIG_WATCHDOG=y
CONFIG_ARM_SP805_WATCHDOG=y
CONFIG_S3C2410_WATCHDOG=y
CONFIG_IMX2_WDT=y
CONFIG_MESON_GXBB_WATCHDOG=m
CONFIG_MESON_WATCHDOG=m
CONFIG_RENESAS_WDT=y
CONFIG_UNIPHIER_WATCHDOG=y
CONFIG_BCM2835_WDT=y
CONFIG_MFD_ALTERA_SYSMGR=y
CONFIG_MFD_BD9571MWV=y
CONFIG_MFD_AXP20X_I2C=y
CONFIG_MFD_AXP20X_RSB=y
CONFIG_MFD_CROS_EC=y
CONFIG_MFD_CROS_EC_CHARDEV=m
CONFIG_MFD_EXYNOS_LPASS=m
CONFIG_MFD_HI6421_PMIC=y
CONFIG_MFD_HI655X_PMIC=y
CONFIG_MFD_MAX77620=y
CONFIG_MFD_SPMI_PMIC=y
CONFIG_MFD_RK808=y
CONFIG_MFD_SEC_CORE=y
CONFIG_REGULATOR_FIXED_VOLTAGE=y
CONFIG_REGULATOR_AXP20X=y
CONFIG_REGULATOR_BD9571MWV=y
CONFIG_REGULATOR_FAN53555=y
CONFIG_REGULATOR_GPIO=y
CONFIG_REGULATOR_HI6421V530=y
CONFIG_REGULATOR_HI655X=y
CONFIG_REGULATOR_MAX77620=y
CONFIG_REGULATOR_MAX8973=y
CONFIG_REGULATOR_PFUZE100=y
CONFIG_REGULATOR_PWM=y
CONFIG_REGULATOR_QCOM_RPMH=y
CONFIG_REGULATOR_QCOM_SMD_RPM=y
CONFIG_REGULATOR_QCOM_SPMI=y
CONFIG_REGULATOR_RK808=y
CONFIG_REGULATOR_S2MPS11=y
CONFIG_REGULATOR_VCTRL=m
CONFIG_RC_CORE=m
CONFIG_RC_DECODERS=y
CONFIG_RC_DEVICES=y
CONFIG_IR_MESON=m
CONFIG_MEDIA_SUPPORT=m
CONFIG_MEDIA_CAMERA_SUPPORT=y
CONFIG_MEDIA_ANALOG_TV_SUPPORT=y
CONFIG_MEDIA_DIGITAL_TV_SUPPORT=y
CONFIG_MEDIA_CONTROLLER=y
CONFIG_VIDEO_V4L2_SUBDEV_API=y
# CONFIG_DVB_NET is not set
CONFIG_MEDIA_USB_SUPPORT=y
CONFIG_USB_VIDEO_CLASS=m
CONFIG_V4L_PLATFORM_DRIVERS=y
CONFIG_VIDEO_SUN6I_CSI=m
CONFIG_V4L_MEM2MEM_DRIVERS=y
CONFIG_VIDEO_SAMSUNG_S5P_JPEG=m
CONFIG_VIDEO_SAMSUNG_S5P_MFC=m
CONFIG_VIDEO_SAMSUNG_EXYNOS_GSC=m
CONFIG_VIDEO_RENESAS_FCP=m
CONFIG_VIDEO_RENESAS_VSP1=m
CONFIG_DRM=m
CONFIG_DRM_NOUVEAU=m
CONFIG_DRM_EXYNOS=m
CONFIG_DRM_EXYNOS5433_DECON=y
CONFIG_DRM_EXYNOS7_DECON=y
CONFIG_DRM_EXYNOS_DSI=y
# CONFIG_DRM_EXYNOS_DP is not set
CONFIG_DRM_EXYNOS_HDMI=y
CONFIG_DRM_EXYNOS_MIC=y
CONFIG_DRM_ROCKCHIP=m
CONFIG_ROCKCHIP_ANALOGIX_DP=y
CONFIG_ROCKCHIP_CDN_DP=y
CONFIG_ROCKCHIP_DW_HDMI=y
CONFIG_ROCKCHIP_DW_MIPI_DSI=y
CONFIG_ROCKCHIP_INNO_HDMI=y
CONFIG_DRM_RCAR_DU=m
CONFIG_DRM_SUN4I=m
CONFIG_DRM_SUN8I_DW_HDMI=m
CONFIG_DRM_SUN8I_MIXER=m
CONFIG_DRM_TEGRA=m
CONFIG_DRM_PANEL_SIMPLE=m
CONFIG_DRM_SII902X=m
CONFIG_DRM_I2C_ADV7511=m
CONFIG_DRM_VC4=m
CONFIG_DRM_HISI_HIBMC=m
CONFIG_DRM_HISI_KIRIN=m
CONFIG_DRM_MESON=m
CONFIG_DRM_PL111=m
CONFIG_FB=y
CONFIG_FB_MODE_HELPERS=y
CONFIG_BACKLIGHT_GENERIC=m
CONFIG_BACKLIGHT_PWM=m
CONFIG_BACKLIGHT_LP855X=m
CONFIG_LOGO=y
# CONFIG_LOGO_LINUX_MONO is not set
# CONFIG_LOGO_LINUX_VGA16 is not set
CONFIG_SOUND=y
CONFIG_SND=y
CONFIG_SND_HDA_TEGRA=m
CONFIG_SND_HDA_CODEC_HDMI=m
CONFIG_SND_SOC=y
CONFIG_SND_BCM2835_SOC_I2S=m
CONFIG_SND_MESON_AXG_SOUND_CARD=m
CONFIG_SND_SOC_ROCKCHIP=m
CONFIG_SND_SOC_ROCKCHIP_SPDIF=m
CONFIG_SND_SOC_ROCKCHIP_RT5645=m
CONFIG_SND_SOC_RK3399_GRU_SOUND=m
CONFIG_SND_SOC_SAMSUNG=y
CONFIG_SND_SOC_RCAR=m
CONFIG_SND_SOC_AK4613=m
CONFIG_SND_SOC_ES7134=m
CONFIG_SND_SOC_ES7241=m
CONFIG_SND_SOC_PCM3168A_I2C=m
CONFIG_SND_SOC_TAS571X=m
CONFIG_SND_SIMPLE_CARD=m
CONFIG_SND_AUDIO_GRAPH_CARD=m
CONFIG_I2C_HID=m
CONFIG_USB=y
CONFIG_USB_OTG=y
CONFIG_USB_XHCI_HCD=y
CONFIG_USB_XHCI_TEGRA=y
CONFIG_USB_EHCI_HCD=y
CONFIG_USB_EHCI_EXYNOS=y
CONFIG_USB_EHCI_HCD_PLATFORM=y
CONFIG_USB_OHCI_HCD=y
CONFIG_USB_OHCI_EXYNOS=y
CONFIG_USB_OHCI_HCD_PLATFORM=y
CONFIG_USB_RENESAS_USBHS=m
CONFIG_USB_STORAGE=y
CONFIG_USB_MUSB_HDRC=y
CONFIG_USB_MUSB_SUNXI=y
CONFIG_USB_DWC3=y
CONFIG_USB_DWC2=y
CONFIG_USB_CHIPIDEA=y
CONFIG_USB_CHIPIDEA_UDC=y
CONFIG_USB_CHIPIDEA_HOST=y
CONFIG_USB_ISP1760=y
CONFIG_USB_HSIC_USB3503=y
CONFIG_NOP_USB_XCEIV=y
CONFIG_USB_ULPI=y
CONFIG_USB_GADGET=y
CONFIG_USB_RENESAS_USBHS_UDC=m
CONFIG_USB_RENESAS_USB3=m
CONFIG_MMC=y
CONFIG_MMC_BLOCK_MINORS=32
CONFIG_MMC_ARMMMCI=y
CONFIG_MMC_SDHCI=y
CONFIG_MMC_SDHCI_ACPI=y
CONFIG_MMC_SDHCI_PLTFM=y
CONFIG_MMC_SDHCI_OF_ARASAN=y
CONFIG_MMC_SDHCI_OF_ESDHC=y
CONFIG_MMC_SDHCI_CADENCE=y
CONFIG_MMC_SDHCI_ESDHC_IMX=y
CONFIG_MMC_SDHCI_TEGRA=y
CONFIG_MMC_SDHCI_F_SDH30=y
CONFIG_MMC_MESON_GX=y
CONFIG_MMC_SDHCI_MSM=y
CONFIG_MMC_SPI=y
CONFIG_MMC_SDHI=y
CONFIG_MMC_UNIPHIER=y
CONFIG_MMC_DW=y
CONFIG_MMC_DW_EXYNOS=y
CONFIG_MMC_DW_HI3798CV200=y
CONFIG_MMC_DW_K3=y
CONFIG_MMC_DW_ROCKCHIP=y
CONFIG_MMC_SUNXI=y
CONFIG_MMC_BCM2835=y
CONFIG_MMC_SDHCI_XENON=y
CONFIG_NEW_LEDS=y
CONFIG_LEDS_CLASS=y
CONFIG_LEDS_GPIO=y
CONFIG_LEDS_PWM=y
CONFIG_LEDS_SYSCON=y
CONFIG_LEDS_TRIGGER_DISK=y
CONFIG_LEDS_TRIGGER_HEARTBEAT=y
CONFIG_LEDS_TRIGGER_CPU=y
CONFIG_LEDS_TRIGGER_DEFAULT_ON=y
CONFIG_LEDS_TRIGGER_PANIC=y
CONFIG_EDAC=y
CONFIG_EDAC_GHES=y
CONFIG_RTC_CLASS=y
CONFIG_RTC_DRV_MAX77686=y
CONFIG_RTC_DRV_RK808=m
CONFIG_RTC_DRV_RX8581=m
CONFIG_RTC_DRV_S5M=y
CONFIG_RTC_DRV_DS3232=y
CONFIG_RTC_DRV_EFI=y
CONFIG_RTC_DRV_CROS_EC=y
CONFIG_RTC_DRV_S3C=y
CONFIG_RTC_DRV_PL031=y
CONFIG_RTC_DRV_SUN6I=y
CONFIG_RTC_DRV_ARMADA38X=y
CONFIG_RTC_DRV_TEGRA=y
CONFIG_RTC_DRV_IMX_SC=m
CONFIG_RTC_DRV_XGENE=y
CONFIG_DMADEVICES=y
CONFIG_FSL_EDMA=y
CONFIG_DMA_BCM2835=m
CONFIG_K3_DMA=y
CONFIG_MV_XOR=y
CONFIG_MV_XOR_V2=y
CONFIG_PL330_DMA=y
CONFIG_TEGRA20_APB_DMA=y
CONFIG_QCOM_BAM_DMA=y
CONFIG_QCOM_HIDMA_MGMT=y
CONFIG_QCOM_HIDMA=y
CONFIG_RCAR_DMAC=y
CONFIG_RENESAS_USB_DMAC=m
CONFIG_VFIO=y
CONFIG_VFIO_PCI=y
CONFIG_VIRTIO_PCI=y
CONFIG_VIRTIO_BALLOON=y
CONFIG_VIRTIO_MMIO=y
CONFIG_XEN_GNTDEV=y
CONFIG_XEN_GRANT_DEV_ALLOC=y
CONFIG_CROS_EC_I2C=y
CONFIG_CROS_EC_SPI=y
CONFIG_COMMON_CLK_RK808=y
CONFIG_COMMON_CLK_SCPI=y
CONFIG_COMMON_CLK_CS2000_CP=y
CONFIG_COMMON_CLK_S2MPS11=y
CONFIG_CLK_QORIQ=y
CONFIG_COMMON_CLK_PWM=y
CONFIG_CLK_IMX8MQ=y
CONFIG_CLK_IMX8QXP=y
CONFIG_TI_SCI_CLK=y
CONFIG_COMMON_CLK_QCOM=y
CONFIG_QCOM_CLK_SMD_RPM=y
CONFIG_QCOM_CLK_RPMH=y
CONFIG_IPQ_GCC_8074=y
CONFIG_MSM_GCC_8916=y
CONFIG_MSM_GCC_8994=y
CONFIG_MSM_MMCC_8996=y
CONFIG_MSM_GCC_8998=y
CONFIG_QCS_GCC_404=y
CONFIG_SDM_GCC_845=y
CONFIG_HWSPINLOCK=y
CONFIG_HWSPINLOCK_QCOM=y
CONFIG_ARM_MHU=y
CONFIG_IMX_MBOX=y
CONFIG_PLATFORM_MHU=y
CONFIG_BCM2835_MBOX=y
CONFIG_TI_MESSAGE_MANAGER=y
CONFIG_QCOM_APCS_IPC=y
CONFIG_ROCKCHIP_IOMMU=y
CONFIG_TEGRA_IOMMU_SMMU=y
CONFIG_ARM_SMMU=y
CONFIG_ARM_SMMU_V3=y
CONFIG_QCOM_IOMMU=y
CONFIG_REMOTEPROC=m
CONFIG_QCOM_Q6V5_MSS=m
CONFIG_QCOM_Q6V5_PAS=m
CONFIG_QCOM_SYSMON=m
CONFIG_RPMSG_QCOM_GLINK_RPM=y
CONFIG_RPMSG_QCOM_GLINK_SMEM=m
CONFIG_RPMSG_QCOM_SMD=y
CONFIG_RASPBERRYPI_POWER=y
CONFIG_QCOM_COMMAND_DB=y
CONFIG_QCOM_GENI_SE=y
CONFIG_QCOM_GLINK_SSR=m
CONFIG_QCOM_RPMH=y
CONFIG_QCOM_SMEM=y
CONFIG_QCOM_SMD_RPM=y
CONFIG_QCOM_SMP2P=y
CONFIG_QCOM_SMSM=y
CONFIG_ARCH_R8A774A1=y
CONFIG_ARCH_R8A774C0=y
CONFIG_ARCH_R8A7795=y
CONFIG_ARCH_R8A7796=y
CONFIG_ARCH_R8A77965=y
CONFIG_ARCH_R8A77970=y
CONFIG_ARCH_R8A77980=y
CONFIG_ARCH_R8A77990=y
CONFIG_ARCH_R8A77995=y
CONFIG_ROCKCHIP_PM_DOMAINS=y
CONFIG_ARCH_TEGRA_132_SOC=y
CONFIG_ARCH_TEGRA_210_SOC=y
CONFIG_ARCH_TEGRA_186_SOC=y
CONFIG_ARCH_TEGRA_194_SOC=y
CONFIG_ARCH_K3_AM6_SOC=y
CONFIG_SOC_TI=y
CONFIG_TI_SCI_PM_DOMAINS=y
CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND=y
CONFIG_EXTCON_USB_GPIO=y
CONFIG_EXTCON_USBC_CROS_EC=y
CONFIG_MEMORY=y
CONFIG_IIO=y
CONFIG_EXYNOS_ADC=y
CONFIG_ROCKCHIP_SARADC=m
CONFIG_IIO_CROS_EC_SENSORS_CORE=m
CONFIG_IIO_CROS_EC_SENSORS=m
CONFIG_IIO_CROS_EC_LIGHT_PROX=m
CONFIG_IIO_CROS_EC_BARO=m
CONFIG_PWM=y
CONFIG_PWM_BCM2835=m
CONFIG_PWM_CROS_EC=m
CONFIG_PWM_MESON=m
CONFIG_PWM_RCAR=m
CONFIG_PWM_ROCKCHIP=y
CONFIG_PWM_SAMSUNG=y
CONFIG_PWM_SUN4I=m
CONFIG_PWM_TEGRA=m
CONFIG_RESET_TI_SCI=y
CONFIG_PHY_XGENE=y
CONFIG_PHY_SUN4I_USB=y
CONFIG_PHY_HI6220_USB=y
CONFIG_PHY_HISTB_COMBPHY=y
CONFIG_PHY_HISI_INNO_USB2=y
CONFIG_PHY_MVEBU_CP110_COMPHY=y
CONFIG_PHY_QCOM_QMP=m
CONFIG_PHY_QCOM_USB_HS=y
CONFIG_PHY_RCAR_GEN3_PCIE=y
CONFIG_PHY_RCAR_GEN3_USB2=y
CONFIG_PHY_RCAR_GEN3_USB3=m
CONFIG_PHY_ROCKCHIP_EMMC=y
CONFIG_PHY_ROCKCHIP_INNO_HDMI=m
CONFIG_PHY_ROCKCHIP_INNO_USB2=y
CONFIG_PHY_ROCKCHIP_PCIE=m
CONFIG_PHY_ROCKCHIP_TYPEC=y
CONFIG_PHY_UNIPHIER_USB2=y
CONFIG_PHY_UNIPHIER_USB3=y
CONFIG_PHY_TEGRA_XUSB=y
CONFIG_HISI_PMU=y
CONFIG_QCOM_L2_PMU=y
CONFIG_QCOM_L3_PMU=y
CONFIG_QCOM_QFPROM=y
CONFIG_ROCKCHIP_EFUSE=y
CONFIG_UNIPHIER_EFUSE=y
CONFIG_MESON_EFUSE=m
CONFIG_FPGA=y
CONFIG_FPGA_MGR_STRATIX10_SOC=m
CONFIG_FPGA_BRIDGE=m
CONFIG_ALTERA_FREEZE_BRIDGE=m
CONFIG_FPGA_REGION=m
CONFIG_OF_FPGA_REGION=m
CONFIG_TEE=y
CONFIG_OPTEE=y
CONFIG_EXT2_FS=y
CONFIG_EXT3_FS=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_BTRFS_FS=m
CONFIG_BTRFS_FS_POSIX_ACL=y
CONFIG_FANOTIFY=y
CONFIG_FANOTIFY_ACCESS_PERMISSIONS=y
CONFIG_QUOTA=y
CONFIG_AUTOFS4_FS=y
CONFIG_FUSE_FS=m
CONFIG_CUSE=m
CONFIG_OVERLAY_FS=m
CONFIG_VFAT_FS=y
CONFIG_HUGETLBFS=y
CONFIG_CONFIGFS_FS=y
CONFIG_EFIVAR_FS=y
CONFIG_SQUASHFS=y
CONFIG_NFS_FS=y
CONFIG_NFS_V4=y
CONFIG_NFS_V4_1=y
CONFIG_NFS_V4_2=y
CONFIG_ROOT_NFS=y
CONFIG_9P_FS=y
CONFIG_NLS_CODEPAGE_437=y
CONFIG_NLS_ISO8859_1=y
CONFIG_SECURITY=y
CONFIG_CRYPTO_ECHAINIV=y
CONFIG_CRYPTO_ANSI_CPRNG=y
CONFIG_DMA_CMA=y
CONFIG_CMA_SIZE_MBYTES=32
CONFIG_PRINTK_TIME=y
CONFIG_DEBUG_INFO=y
CONFIG_DEBUG_FS=y
CONFIG_MAGIC_SYSRQ=y
CONFIG_DEBUG_KERNEL=y
# CONFIG_SCHED_DEBUG is not set
# CONFIG_DEBUG_PREEMPT is not set
# CONFIG_FTRACE is not set
CONFIG_MEMTEST=y
在linux内核根目录下执行如下命令，执行完之后会在内核根目录下生成默认配置文件.config：
root@zhengyang:/work/sambashare/rk3399/linux-5.2.8# make defconfig
HOSTCC scripts/basic/fixdep
HOSTCC scripts/kconfig/conf.o
HOSTCC scripts/kconfig/confdata.o
HOSTCC scripts/kconfig/expr.o
LEX scripts/kconfig/lexer.lex.c
YACC scripts/kconfig/parser.tab.h
HOSTCC scripts/kconfig/lexer.lex.o
YACC scripts/kconfig/parser.tab.c
HOSTCC scripts/kconfig/parser.tab.o
HOSTCC scripts/kconfig/preprocess.o
HOSTCC scripts/kconfig/symbol.o
HOSTLD scripts/kconfig/conf
*** Default configuration is based on 'defconfig'
#
# configuration written to .config
#
1.4 内核裁切
我们可以通过make menuconfig配置内核支持的功能：
root@zhengyang:/work/sambashare/rk3399/linux-5.2.8# make menuconfig
打开如下页面：
1.4.1 支持设备树
实际上在linux 5.2.8版本内核已经把设备树作为默认配置项了，因此也不需要我们配置了。
内核在启动时，会执行setup_arch函数，该函数用于在内核启动期间对硬件进行初始化，包括设置 CPU、内存、设备树等等。该函数的实现是针对特定架构的，因此不同的架构会有不同的 setup_arch实现。以ARM(非ARM64)为例：
setup_arch(&command_line); // arch/arm/kernel/setup.c
mdesc = setup_machine_fdt(__atags_pointer); // arch/arm/kernel/devtree.c
// 检验设备树头部，判断设备树有效性
early_init_dt_verify(phys_to_virt(dt_phys) // drivers/of/fdt.c
initial_boot_params = params;
// 找到最匹配的machine_desc
mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach); // drivers/of/fdt.c
early_init_dt_scan_nodes() // drivers/of/fdt.c
// 从dtb文件中读取chosen节点的信息,包括命令行boot_command_line,initrd location及size
of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line)
// 得到根节点的 #address-cells 和 #size-cells属性信息
of_scan_flat_dt(early_init_dt_scan_root, NULL)
// 得到/memory节点的reg属性
of_scan_flat_dt(early_init_dt_scan_memory, NULL)
machine_desc = mdesc;
......
of_flat_dt_match_machine函数通过遍历所有的machine_desc，找到与设备树中compatible最匹配的一个machine_desc(每一个开发板都对应一个machine_desc，通过它定义开发板相关的一些属性及函数，比如机器类型ID、中断初始化函数、I/O映射函数、machine初始化函数等；这些函数会在内核启动阶段被回调，在较早的版本中，init_machine会包含大量的平台设备注册的代码)。
然而在ARM64中，其实现发生了改变：
setup_arch(&command_line); // arch/arm64/kernel/setup.c
// 参数为dtb在内存的首地址
setup_machine_fdt(__fdt_pointer) // arch/arm64/kernel/setup.c
// 为fdt建立地址映射，在该函数的最后，顺便就调用memblock_reserve保留了该段内存
void *dt_virt = fixmap_remap_fdt(dt_phys)
// 校验并解析dtb文件
early_init_dt_scan(dt_virt) // drivers/of/fdt.c
// 检验设备树头部，判断设备树有效性
early_init_dt_verify()
early_init_dt_scan_nodes() // drivers/of/fdt.c
// 从dtb文件中读取chosen节点的信息,包括命令行boot_command_line,initrd location及size
of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line)
// 得到根节点的 #address-cells 和 #size-cells属性信息
of_scan_flat_dt(early_init_dt_scan_root, NULL)
// 得到/memory节点的reg属性
of_scan_flat_dt(early_init_dt_scan_memory, NULL)
// 获取machine名称
name = of_flat_dt_get_machine_name(); // drivers/of/fdt.c
// 获取设备树的根节点
unsigned long dt_root = of_get_flat_dt_root()
// 这里直接获取设备树的model属性
name = of_get_flat_dt_prop(dt_root, "model", NULL)
parse_early_param();
......
arm64_memblock_init()
......
// 解析dtb文件，转换成节点是device_node的树状结构, 其中设备节点会被转换为device_node结构
unflatten_device_tree()
......
可以看到这里没有了设备树和machine_desc的匹配过程了，也就是说ARM64已经完全抛弃了machine_desc，全部采用设备树的实现方式，关于为什么要采用设备树我在设备树章节已经具体介绍过。
1.4.2 支持NFS文件系统
使用NFS作为根文件系统，因为文件系统在宿主机中，这样在修改文件系统就非常方便，主要用于开发阶段使用。
File systems --->
[*] Network File Systems --->
<*> NFS client support for NFS version 4
勾选NFS client support for NFS version 4。
1.4.3 配置uevent helper
配置Support for uevent helper；
Device Drivers --->
Generic Driver Options --->
[*] Support for uevent helper
(/sbin/mdev) pa