Rockchip RK3588 - uboot引导方式介绍
本帖最后由 ZXjsy 于 2025-3-5 17:48 编辑开发板 ：RK3588 EVB开发板
eMMC ：256GB
LPDDR4 ：16GB
显示屏 ：10.1英寸HDMI接口显示屏
u-boot ：2017.09
linux ：6.1
在前面的文章我们对Rockhip Linux SDK进行了深入分析，其中涉及到了SDK编译过程、编译源码，具体可以参考：Rockchip RK3588 - Rockchip Linux SDK编译；（如需要此文档的可以联系博主获取）Rockchip RK3588 - Rockchip Linux SDK Buildroot文件系统构建；（如需要此文档的可以联系博主获取）Rockchip RK3588 - Rockchip Linux SDK脚本分析。（如需要此文档的可以联系博主获取）此外，我们还是深入分析了Recovery模式下的系统升级功能，具体可参考：Rockchip RK3588 - Rockchip Linux Recovery updateEngine源码分析；（如需要此文档的可以联系博主获取）Rockchip RK3588 - Rockchip Linux Recovery updateEngine测试。 （如需要此文档的可以联系博主获取）接下来我们将尝试在RK3588开发板实现系统升级功能，当然我们还期望当根文件系统损坏时，开发板能够通过按住GPIO口进入到recovery系统恢复正常系统。一、uboot启动方式既然要实现在开发板实现系统升级功能，我们就需要了解uboot启动内核的方式，并制作以下分区镜像；misc.img：misc分区是一个没有文件系统的分区，用于存放一些引导配置参数；recovery.img：由kernel + dtb + ramdisk组成，主要用于升级操作；uboot会根据misc分区存放的字段来判断将要引导的系统是normal系统还是recovery系统。1.1 系统固件我们使用的是RK3588开发板，这里我们就去下载官方提供的固件这里我们选择debian-bullseye-desktop-arm64-images.tgz作为测试使用的镜像文件，将debian-bullseye-desktop-arm64-images.tgz（位于"�3_分区镜像文件"目录下，以实际下载的文件为准）拷贝到/work/sambashare/rk3588/friendly/sd-fuse_rk3588目录下；root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# ll debian*-rwxrw-rw- 1 root root 1590466719 Dec3 01:49 debian-bullseye-desktop-arm64-images.tgz*-rwxrw-rw- 1 root root 75 Nov 18 19:05 debian-bullseye-desktop-arm64-images.tgz.hash.md5*root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# tar -xvzf debian-bullseye-desktop-arm64-images.tgz解压得到debian-bullseye-desktop-arm64文件夹；root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# ll debian-bullseye-desktop-arm64-rw-r--r--1 root root 8072140 May 282023 boot.img-rw-r--r--1 root root 1424 May 282023 dtbo.img-rw-r--r--1 root root 307200 Sep8 23:33 idbloader.img-rw-r--r--1 root root 64 Nov 17 10:03 info.conf-rw-r--r--1 root root 35551252 Nov 16 16:17 kernel.img-rw-r--r--1 root root 471488 Sep8 23:33 MiniLoaderAll.bin-rw-r--r--1 root root 49152 May 282023 misc.img-rw-r--r--1 root root 470 Nov 17 10:03 parameter.txt-rw-r--r--1 root root 6227456 Nov 16 16:17 resource.img-rw-r--r--1 root root 3992675220 Nov 17 10:03 rootfs.img-rw-r--r--1 root root 4194304 Sep8 23:33 uboot.img-rw-r--r--1 root root 159868 Nov 17 10:03 userdata.img可以看到解压的文件已经包含了misc.img，但是并没有recovery.img。1.1.1 系统分区介绍parameter.txt保存着分区信息：FIRMWARE_VER: 12.0MACHINE_MODEL: RK3588MACHINE_ID: 007MANUFACTURER: RK3588MAGIC: 0x5041524BATAG: 0x00200800MACHINE: NanoPi6CHECK_MASK: 0x80PWR_HLD: 0,0,A,0,1TYPE: GPTCMDLINE: mtdparts=rk29xxnand:0x00002000@0x00004000(uboot),0x00002000@0x00006000(misc),0x00002000@0x00008000(dtbo),0x00008000@0x0000a000(resource),0x00014000@0x00012000(kernel),0x00010000@0x00026000(boot),0x00010000@0x00036000(recovery),0x007c0000@0x00046000(rootfs),-@0x00806000(userdata:grow)解析信息如下：
NumberName镜像文件Start (sector)End (sector)Size
1ubootuboot.img0x4000（16384）0x5FFF4M
2miscmisc.img0x6000（24576）0x7FFF4M
3dtbodtbo.img0x8000（32768）0x9FFF4M
4resourceresource.img0xa000（40960）0x11FFF16MB
5kernelkernel.img0x12000（73728）0x25FFF40MB
6bootboot.img0x26000（155648）0x35FFF32MB
7recoveryrecovery.img0x36000（221184）0x45FFF32MB
8rootfsrootfs.img0x46000（286720）0x804FFF3.968GB
9userdatauserdata.img0x806000（8413184）-
其中：uboot分区：供uboot编译出来的uboot.img；misc分区：引导参数分区，供misc.img，给recovery使用；dtbo：：供kernel编译出来的dtbo.img；resource：资源分区，由设备树、图片资源文件组成，不包含内核；boot：供kernel编译出来的boot.img（可能是FIT uImage镜像格式，也有可能是Android bootimg镜像格式）；kernel：供kernel编译出来的kernel.img（由tools/mkkrnlimg工具编译内核镜像Image文件得到）；recovery分区：供recovery编译出的recovery.img（kernel + dtb + ramdisk）；rootfs分区：供buildroot、debian或yocto编出来的rootfs.img；userdata分区：供APP临时生成文件或给最终用户使用，挂载在/userdata目录下。从上面我们可以看到这里有两个分区时存放了内核镜像，分别是boot和kernel，那问题来了，uboot启动到底使用的是哪个内核呢？1.1.2 生成统一固件将debian-bullseye-desktop-arm64目录下的镜像文件重新打包成SD卡固件：root@@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# sudo ./mk-sd-image.sh debian-bullseye-desktop-arm64/Creating RAW image: out/rk3588-sd-debian-bullseye-desktop-6.1-arm64-20240714.img (7800 MB)---------------------------------记录了0+0 的读入记录了0+0 的写出0字节已复制，0.0001181 s，0.0 kB/s---------------------------------------------------------------- capacity = 7438MB, 7799999488 bytescurrent out/rk3588-sd-debian-bullseye-desktop-6.1-arm64-20240714.img partition:----------------------------------------------------------------parsing ./debian-bullseye-desktop-arm64//parameter.txt:create new GPT 9:----------------------------------------------------------------copy from: ./debian-bullseye-desktop-arm64 to out/rk3588-sd-debian-bullseye-desktop-6.1-arm64-20240714.img : 300 KB | ./debian-bullseye-desktop-arm64/idbloader.img> 100% : done. : 4096 KB | ./debian-bullseye-desktop-arm64/uboot.img > 100% : done. : 48 KB | ./debian-bullseye-desktop-arm64/misc.img > 100% : done. : 1 KB | ./debian-bullseye-desktop-arm64/dtbo.img > 100% : done. : 2518 KB | ./debian-bullseye-desktop-arm64/resource.img > 100% : done. : 34590 KB | ./debian-bullseye-desktop-arm64/kernel.img > 100% : done. : 7882 KB | ./debian-bullseye-desktop-arm64/boot.img > 100% : done. :3907280 KB | ./debian-bullseye-desktop-arm64/rootfs.img > 100% : done. : 156 KB | ./debian-bullseye-desktop-arm64/userdata.img > 100% : done.-------------------------------------------------------------------------------------------------RAW image successfully created (21:09:10).-rw-r--r-- 1 root root 77999994887月 14 21:09 该sh脚本内部调用了Rockchip官方提供的打包工具sd_update生成的统一固件，由于打包工具并不开源，所以无法研究源码。不过我们大致可以猜测出应该就是做了一个镜像文件，然后按照parameter.txt进行划分分区，并将各个分区镜像依次烧录进去。View Code1.1.3 制作SD启动卡我们将SD卡插入PC上，在虚拟机ubuntu中运行demsg查看新接入的设备； usb 2-1: USB disconnect, device number 2 usb 2-1: new high-speed USB device number 3 using ehci-pci usb 2-1: New USB device found, idVendor=14cd, idProduct=1212, bcdDevice= 1.00 usb 2-1: New USB device strings: Mfr=1, Product=3, SerialNumber=2 usb 2-1: Product: Mass Storage Device usb 2-1: Manufacturer: Generic usb 2-1: SerialNumber: 121220160204 usb-storage 2-1:1.0: USB Mass Storage device detected scsi host33: usb-storage 2-1:1.0 scsi 33:0:0:0: Direct-Access Mass Storage Device 1.00 PQ: 0 ANSI: 0 CCS sd 33:0:0:0: Attached scsi generic sg2 type 0 sd 33:0:0:0: 62333952 512-byte logical blocks: (31.9 GB/29.7 GiB) sd 33:0:0:0: Write Protect is off sd 33:0:0:0: Mode Sense: 03 00 00 00 sd 33:0:0:0: No Caching mode page found sd 33:0:0:0: Assuming drive cache: write throughsdb: sdb1 sd 33:0:0:0: Attached SCSI removable disk可以看到SD卡对应的设备节点为/dev/sdb，对应1个分区sdb1；root@@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# sudo ls /dev/sdb*/dev/sdb/dev/sdb1root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# df -hT文件系统 类型 容量已用可用 已用% 挂载点udev devtmpfs3.9G 03.9G 0% /devtmpfs tmpfs 791M3.6M787M 1% /run/dev/sda5 ext4 98G 69G 24G 75% /tmpfs tmpfs 3.9G 03.9G 0% /dev/shmtmpfs tmpfs 5.0M4.0K5.0M 1% /run/locktmpfs tmpfs 3.9G 03.9G 0% /sys/fs/cgroup/dev/sda1 vfat 511M4.0K511M 1% /boot/efi/dev/loop15 squashfs497M497M 0100% /snap/gnome-42-2204/132tmpfs tmpfs 791M 0791M 0% /run/user/0tmpfs tmpfs 791M 36K791M 1% /run/user/1000/dev/sdc2 ext4 11G311M9.8G 4% /media/zhengyang/userdata/dev/sdc1 ext4 4.5G4.4G 35M100% /media/zhengyang/rootfs开始制作SD启动卡：root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# sudo dd if=out/rk3588-sd-debian-bullseye-desktop-6.1-arm64-20240714.img of=/dev/sdb bs=4M status=progress1.2 uboot环境变量将SD卡插入到开发板，并使用准备好的USB转串口适配器和连接线(需另购)，连接开发板，给开发板上电。在启动过程中按下CTRL+C进入uboot命令行模式；View Code1.2.1 启动命令行查看内核启动命令；=> print bootcmdbootcmd=boot_fit;boot_android ${devtype} ${devnum};bootrkp;run distro_bootcmd;1.2.2 启动参数查看内核启动参数：=> pri bootargsbootargs=storagemedia=sd androidboot.storagemedia=sd androidboot.mode=normal androidboot.dtbo_idx=11.2.3 资源文件uboot查看资源文件：# 切换到SD卡所属设备==> mmc dev 1switch to partitions #0, OKmmc1 is current device
==> mmc infoDevice: mmc@fe2c0000Manufacturer ID: 3OEM: 5344Name: SD32GTiming Interface: LegacyTran Speed: 52000000Rd Block Len: 512SD version 3.0High Capacity: YesCapacity: 29.7 GiBBus Width: 4-bitErase Group Size: 512 Bytes
# 从resource分区读取20个扇区数据==> mmc read 0x100000000xa000 20MMC read: dev # 1, block # 40960, count 32 ... 32 blocks read: OK
# 查看前两个扇区数据==> md.b 0x10000000 0x40010000000: 52 53 43 45 00 00 00 00 01 01 01 00 18 00 00 00 RSCE............10000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ......................10000200: 45 4e 54 52 72 6b 33 33 39 39 2d 6e 61 6e 6f 70 ENTRrk3399-nanop10000210: 69 34 2d 72 65 76 30 30 2e 64 74 62 00 00 00 00 i4-rev00.dtb....10000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ......................100002e0: 02 8a cd 4f a8 69 32 dd d0 bd de 09 34 59 ad 6e ...O.i2.....4Y.n100002f0: 7d 42 d6 ac 00 00 00 00 00 00 00 00 00 00 00 00 }B....................这里我们读取resource分区的数据，也就是resource.img镜像，可以看到以上输出内容中包含了设备树文件的数据。1.2.4 设备树查看设备树：=> print dtb_namedtb_name=rk3588-nano0pi6-rev01.dtb1.3 启动内核当我们在uboot命令行执行了boot命令时，uboot会获取bootcmd环境变量的内容，然后执行bootcmd中保存的启动命令。接下来我们来分析一下bootcmd默认配置，在默认环境变量default_environment（位于uboot-rockchip/include/env_default.h）中定义有，其内容大致如下：const uchar default_environment[] = { "bootcmd=" CONFIG_BOOTCOMMAND "�" "bootdelay=" __stringify(CONFIG_BOOTDELAY) "�" "baudrate=" __stringify(CONFIG_BAUDRATE) "�" "ipaddr=" __stringify(CONFIG_IPADDR) "�" "serverip=" __stringify(CONFIG_SERVERIP) "�" "netmask=" __stringify(CONFIG_NETMASK) "�" ......#ifdefCONFIG_EXTRA_ENV_SETTINGS CONFIG_EXTRA_ENV_SETTINGS#endif "�"};默认启动命令CONFIG_BOOTCOMMAND定义在uboot-rockchip/include/configs/nanopi6.h，该文件存放着开发板配置信息，被uboot-rockchip/include/config.h文件引入。#include < configs/rk3588_common.h >
/* Remove or override few declarations from rk3588-common.h */#undef CONFIG_BOOTCOMMAND#undef CONFIG_DISPLAY_BOARDINFO_LATE#undef RKIMG_DET_BOOTDEV#undef RKIMG_BOOTCOMMAND
#define CONFIG_SYS_MMC_ENV_DEV 0#define CONFIG_SYS_MMC_MAX_BLK_COUNT 32768
#define CONFIG_MISC_INIT_R#define CONFIG_SERIAL_TAG
#ifndef CONFIG_SPL_BUILD
#define ROCKCHIP_DEVICE_SETTINGS "stdout=serial,vidconsole�" "stderr=serial,vidconsole�"
#define RKIMG_DET_BOOTDEV "rkimg_bootdev=" "if mmc dev 1 && rkimgtest mmc 1; then " "setenv devtype mmc; setenv devnum 1; echo Boot from SDcard;" "elif mmc dev 0; then " "setenv devtype mmc; setenv devnum 0;" "elif rksfc dev 1; then " "setenv devtype spinor; setenv devnum 1;" "fi; �"
#define RKIMG_BOOTCOMMAND "boot_fit;" "boot_android ${devtype} ${devnum};" "bootrkp;" "run distro_bootcmd;"
#define CONFIG_BOOTCOMMAND RKIMG_BOOTCOMMAND
#endif这里引入了uboot-rockchip/include/configs/rk3588_common.h，而该文件又引入了uboot-rockchip/include/configs/rockchip-common.h。这里支持了内核的4种引导方式：boot_fit：从eMMC中boot/recovery分区（如果进入的是normal系统，则为boot分区；如果进入的是recovery系统，则为recovery分区）加载FIT uImage镜像文件（通常由kernel + dtb + ramdisk组成）到内存，然后启动内核 ；boot_android：启动Android内核镜像；bootrkp：通常用于Rockchip平台上的特定启动操作，可能用于启动特定的固件或者特殊的操作模式；distro_bootcmd：运行uboot环境中定义的 distro_bootcmd，这是一个uboot环境变量，通常包含了一系列的启动命令，比如尝试从网络引导、从存储设备引导等；其中boot_fit、distro_bootcmd启动方式我们在《 Rockchip RK3399 - 移植linux 5.2.8》中有过介绍。1.3.1 内核启动日志输入boot命令启动内核：=> boot## Booting FIT Image FIT: No fit blob # 命令boot_fitFIT: No FIT imageANDROID: reboot reason: "(none)" # 命令boot_androidNot AVB images, AVB skipNo valid android hdrAndroid image load failedAndroid boot failed, error -1.
## Booting Rockchip Format Image # 命令bootrkp fdt @ 0x08300000 (0x000421b2) # fdt加载到内存的地址kernel @ 0x00400000 (0x021c7808) # kernel加载到内存的地址ramdisk@ 0x0a200000 (0x007b2bc0) # ramdisk加载到内存的地址Fdt Ramdisk skip relocation## Flattened Device Tree blob at 0x08300000 Booting using the fdt blob at 0x08300000 Using Device Tree in place at 0000000008300000, end 00000000083451b1## reserved-memory:cma: addr=10000000 size=8000000drm-**@00000000: addr=edf00000 size=468000vendor-storage-rm@00000000: addr=ebcd3000 size=10000ramoops@110000: addr=110000 size=e0000Adding bank: 0x00200000 - 0x08400000 (size: 0x08200000)Adding bank: 0x09400000 - 0xf0000000 (size: 0xe6c00000)Adding bank: 0x100000000 - 0x3fc000000 (size: 0x2fc000000)Adding bank: 0x3fc500000 - 0x3fff00000 (size: 0x03a00000)Adding bank: 0x4f0000000 - 0x500000000 (size: 0x10000000)Total: 10246.299/11135.828 ms
Starting kernel ...
[ 11.146608] Booting Linux on physical CPU 0x0000000000 [ 11.146631] Linux version 6.1.25 (root@ubuntu) (aarch64-linux-gnu-gcc (Ubuntu 10.5.0-1ubuntu1~20.04) 10.5.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #1 SMP Wed Dec 27 21:53:18 CST 2023[ 11.153743] Machine model: FriendlyElec NanoPC-T6......[ 11.510154] Kernel command line: storagemedia=sd androidboot.storagemedia=sd androidboot.mode=normal androidboot.dtbo_idx=1 androidboot.verifiedbootstate=orange earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 coherent_pool=1m irqchip.gicv3_pseudo_nmi=0 rw root=/dev/mmcblk0p8 rootfstype=ext4 data=/dev/mmcblk0p9 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1......Debian GNU/Linux 11 NanoPC-T6 ttyFIQ0
NanoPC-T6 login: [ 20.885195] systemd-journald: File /var/log/journal/b9164042f80842f6968af54e1d15c9af/user-1000.journal corrupted or uncleanly shut down, renaming and replacing.[ 21.783657] rk_hdmirx fdee0000.hdmirx-controller: hdmirx_audio_startup: device is no connected or audio is off[ 26.433687] platform mtd_vendor_storage: deferred probe pending
NanoPC-T6 login:(1) 首先执行boot_fit命令，对于FIT uImage，其中地址范围0x00000000~0x00000027表示的是fdt_header结构体的成员信息。因此会调用fit_get_blob函数获取boot/recovery分区（如果进入的是normal系统，则获取boot分区；如果进入的是recovery系统，则获取recovery分区）第一个扇区数据，并对fdt_header结构体进行校验判断是不是FIT uImage。由于正常情况下我们进入的是normal系统，则从boot分区加载boot.img数据，从输出的日志信息可以看出我们烧录的boot.img并不是FIT uIamge。(2) 接着执行boot_android命令，从输出日志可以看到应该也是引导失败了。(3) 执行bootrkp命令。(4) 执行distro_bootcmd命令。有关bootrkp和distro_bootcmd启动方式，我们接下来详细介绍。1.3.2 加载命令行不知道你有没有留意内核启动输出命令行信息；[ 11.510154] Kernel command line: storagemedia=sd androidboot.storagemedia=sd androidboot.mode=normal androidboot.dtbo_idx=1 androidboot.verifiedbootstate=orange earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 coherent_pool=1m irqchip.gicv3_pseudo_nmi=0 rw root=/dev/mmcblk0p8 rootfstype=ext4 data=/dev/mmcblk0p9 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1这里输出的信息为啥和bootargs环境变量以及arch/arm64/boot/dts/rockchip/rk3588-nanopi6-common.dtsi内容不一样呢？=> pri bootargsbootargs=storagemedia=sd androidboot.storagemedia=sd androidboot.mode=normal androidboot.dtbo_idx=1
# 设备树设备节点内容chosen: chosen { bootargs = "earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 coherent_pool=1m irqchip.gicv3_pseudo_nmi=0";};那么我们不得不介绍内核启动后是如何获取到启动参数。对于ARM64来说，uboot在启动内核时会将r2设置为dtb文件的开始地址。1.3.2.1 内核bootargs来源对于开发板开发板而言，r2设置为了rk3588-nanopi6-rev01.dtb加载到内存的地址。这里我们直接从内核start_kernel函数开始说起，其位于init/main.c文件，函数调用栈如下；#char __initdata boot_command_line; // 全局变量，定义在init/main.c
start_kernel()// init/main.c char *command_line; ....... setup_arch(&command_line);// arch/arm64/kernel/setup.c ...... *cmdline_p = boot_command_line; ...... // __fdt_pointer:dtb所在的物理地址，由bootloader通过x0寄存器传递过来 setup_machine_fdt(__fdt_pointer); // arch/arm64/kernel/setup.c // 返回dtb所在的虚拟地址dt_virt void *dt_virt = fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL) if (!dt_virt || !early_init_dt_scan(dt_virt)) { ........ } name = of_flat_dt_get_machine_name(); pr_info("Machine model: %sn", name);machine_desc = mdesc; ......这里我们重点关注early_init_dt_scan函数，early_init_dt_scan主要是对dtb进行早期的扫描工作，下面是简要介绍函数的调用流程和实现细节:early_init_dt_scan(dt_virt) // drivers/of/fdt.c // 对dtb头进行检查 early_init_dt_verify(dt_virt) early_init_dt_scan_nodes() // 遍历设备树的节点，解析出重要的信息用于内核启动 /* Retrieve various information from the /chosen node */ of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line); /* Initialize {size,address}-cells info */ of_scan_flat_dt(early_init_dt_scan_root, NULL); /* Setup memory, calling early_init_dt_add_memory_arch */ of_scan_flat_dt(early_init_dt_scan_memory, NULL);of_scan_flat_dt对dtb里面的所有节点进行扫描，用提供的回调函数循环处理节点信息，回调函数返回0继续扫描，返回非0结束扫描，当扫描到最后一个节点也会结束扫描；/** * of_scan_flat_dt - scan flattened tree blob and call callback on each. * @it: callback function * @data: context data pointer * * This function is used to scan the flattened device-tree, it is * used to extract the memory information at boot before we can * unflatten the tree */int __init of_scan_flat_dt(int (*it)(unsigned long node, const char *uname, int depth, void *data), void *data){ //dtb数据的地址，也就是根节点的地址 const void *blob = initial_boot_params; const char *pathp; int offset, rc = 0, depth = -1;
if (!blob) return 0;
// 从根节点遍历dtb中每个节点，返回的offset就是每个节点的地址 // offset：表示节点的地址相对于根节点的偏移量，也是节点数据所在地址 // depth：代表节点相对于根节点的深度，比如根节点深度是0，/chosen节点是1 for (offset = fdt_next_node(blob, -1, &depth); offset >= 0 && depth >= 0 && !rc; offset = fdt_next_node(blob, offset, &depth)) {
// 解析出节点名称 pathp = fdt_get_name(blob, offset, NULL); if (*pathp == '/') pathp = kbasename(pathp); // 回调函数解析节点，it是传递进来的设备树节点的解析函数，需要解析什么消息就传递进来相应的节点解析函数 rc = it(offset, pathp, depth, data); } return rc;}early_init_dt_scan_chosen用于扫描chosen节点，并把bootargs属性值拷贝到boot_command_line中，如果内核定义了CONFIG_CMDLINE这个宏，则把配置的命令行参数也拷贝到boot_command_line；/* * Convert configs to something easy to use in C code */#if defined(CONFIG_CMDLINE_FORCE)static const int overwrite_incoming_cmdline = 1;static const int read_dt_cmdline;static const int concat_cmdline;#elif defined(CONFIG_CMDLINE_EXTEND)static const int overwrite_incoming_cmdline;static const int read_dt_cmdline = 1;static const int concat_cmdline = 1;#else /* CMDLINE_FROM_BOOTLOADER */ // 走这里static const int overwrite_incoming_cmdline;static const int read_dt_cmdline = 1;static const int concat_cmdline;#endif
#ifdef CONFIG_CMDLINEstatic const char *config_cmdline = CONFIG_CMDLINE;#elsestatic const char *config_cmdline = "";#endif
int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, int depth, void *data){ int l = 0; const char *p = NULL; char *cmdline = data; // 即boot_command_line const void *rng_seed;
pr_debug("search "chosen", depth: %d, uname: %sn", depth, uname);
// 节点的深度要为1，数据不能使NULL，同时节点名字是"chosen"或者"chosen@0" if (depth != 1 || !cmdline || (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0)) return 0;
// 解析initrd相关 early_init_dt_check_for_initrd(node);
/* Put CONFIG_CMDLINE in if forced or if data had nothing in it to start */ if (overwrite_incoming_cmdline || !cmdline)// 进入 strlcpy(cmdline, config_cmdline, COMMAND_LINE_SIZE);
/* Retrieve command line unless forcing */ if (read_dt_cmdline) // 从chosen节点中解析出bootargs属性 p = of_get_flat_dt_prop(node, "bootargs", &l);
if (p != NULL && l > 0) { if (concat_cmdline) { int cmdline_len; int copy_len; strlcat(cmdline, " ", COMMAND_LINE_SIZE); cmdline_len = strlen(cmdline); copy_len = COMMAND_LINE_SIZE - cmdline_len - 1; copy_len = min((int)l, copy_len); strncpy(cmdline + cmdline_len, p, copy_len); cmdline = '�'; } else { // 追加bootargs参数到boot_command_line strlcpy(cmdline, p, min((int)l, COMMAND_LINE_SIZE)); } }
pr_debug("Command line is: %sn", (char*)data);
rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l); if (rng_seed && l > 0) { add_bootloader_randomness(rng_seed, l);
/* try to clear seed so it won't be found. */ fdt_nop_property(initial_boot_params, node, "rng-seed");
/* update CRC check value */ of_fdt_crc32 = crc32_be(~0, initial_boot_params, fdt_totalsize(initial_boot_params)); }
/* break now */ return 1;}如果想查看内核debug级别日志可以配置：# arch/arm64/configs/nanopi6_linux_defconfigKernel hacking---> printk and dmesg options---> (8) Default console loglevel (1-15) # CONFIG_CONSOLE_LOGLEVEL_DEFAULT
# 修改drivers/of/fdt.c即在需要输出debug级别日志的文件头部定义如下宏#define DEBUG通过追加日志，我们重新编译并烧录会发现启动命令行的确是如下这个内容：[ 0.000000] OF: fdt: search "chosen", depth: 1, uname: chosen[ 0.000000] OF: fdt: Looking for initrd properties...[ 0.000000] OF: fdt: initrd_start=0xa200000initrd_end=0xa9b2bc0[ 0.000000] OF: fdt: Command line is: storagemedia=sd androidboot.storagemedia=sd androidboot.mode=normal androidboot.dtbo_idx=1 androidboot.verifiedbootstate=orange earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 coherent_pool=1m irqchip.gicv3_pseudo_nmi=0 rw root=/dev/mmcblk0p8 rootfstype=ext4 data=/dev/mmcblk0p9 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=11.3.2.2dtb中bootargs来源实际上dtb中的bootargs的来源有如下几种；内核启动参数bootargs保存在dts的chosen节点的bootargs属性，这里就是arch/arm64/boot/dts/rockchip/rk3588-nanopi6-common.dtsi这个设备树源文件；bootargs数据可以是在dts源文件中定义，也可以是uboot启动内核时传递给内核；其中uboot传递的bootargs参数优先级高于设备树中定义的bootargs，如果是uboot传递的bootargs，在内核启动阶段就会调用fdt_chosen函数将环境变量中的bootargs参数写进dtb数据中；既然uboot传递了bootargs参数，那么内核将会使用uboot传递过来的bootargs参数，不过该参数为何和内核启动输出的不太一样呢？为此我们不得不去研究bootrkp启动是否追加了启动参数；boot_rockchip_image(dev_desc, &part) // bootrkp启动方式 ...... // 设置内核加载地址（Image镜像） images.ep = kernel_addr_r; images.initrd_start = ramdisk_addr_r; images.initrd_end = ramdisk_addr_r + ramdisk_size; // 设置设备树加载地址 images.ft_addr = (void *)fdt_addr_r; // 设备树长度 images.ft_len = fdt_totalsize(fdt_addr_r); do_bootm_linux(0, 0, NULL, &images); // arch/arm/lib/bootm.cboot_prep_linux(images); // arch/arm/lib/bootm.c image_setup_linux(images) // common/image.c ulong of_size = images->ft_len; char **of_flat_tree = &images->ft_addr; struct lmb *lmb = &images->lmb; boot_fdt_add_mem_rsv_regions(lmb, *of_flat_tree); boot_get_cmdline(lmb, &images->cmdline_start, &images->cmdline_end); boot_relocate_fdt(lmb, of_flat_tree, &of_size); image_setup_libfdt(images, *of_flat_tree, of_size, lmb); // common/image-fdt.c ...... ......
# 可以通过如下代码输出启动参数char *commandline = env_get("bootargs");printf("%s %d:%sn", __func__, __LINE__, commandline);重点关注image_setup_libfdt，定义在common/image-fdt.c；int image_setup_libfdt(bootm_headers_t *images, void *blob, int of_size, struct lmb *lmb){ ulong *initrd_start = &images->initrd_start; ulong *initrd_end = &images->initrd_end; int ret = -EPERM; int fdt_ret;
// 进行架构特定的设备树修正 if (arch_fixup_fdt(blob) < 0) { printf("ERROR: arch-specific fdt fixup failedn"); goto err; }
#if defined(CONFIG_PASS_DEVICE_SERIAL_BY_FDT) // 定义 // 配置根节点 if (fdt_root(blob) < 0) { printf("ERROR: root node setup failedn"); goto err; }#endif // 创建/chosen节点 if (fdt_chosen(blob) < 0) { printf("ERROR: /chosen node create failedn"); goto err; }
/* Update ethernet nodes */ fdt_fixup_ethernet(blob); if (IMAGE_OF_BOARD_SETUP) { fdt_ret = ft_board_setup(blob, gd- >bd); if (fdt_ret) { printf("ERROR: board-specific fdt fixup failed: %sn", fdt_strerror(fdt_ret)); goto err; } } if (IMAGE_OF_SYSTEM_SETUP) { fdt_ret = ft_system_setup(blob, gd->bd); if (fdt_ret) { printf("ERROR: system-specific fdt fixup failed: %sn", fdt_strerror(fdt_ret)); goto err; } }
/* Delete the old LMB reservation */ if (lmb) lmb_free(lmb, (phys_addr_t)(u32)(uintptr_t)blob, (phys_size_t)fdt_totalsize(blob));
ret = fdt_shrink_to_minimum(blob, 0); if (ret < 0) goto err; of_size = ret;
if (*initrd_start && *initrd_end) { of_size += FDT_RAMDISK_OVERHEAD; fdt_set_totalsize(blob, of_size); } /* Create a new LMB reservation */ if (lmb) lmb_reserve(lmb, (ulong)blob, of_size);
fdt_initrd(blob, *initrd_start, *initrd_end); if (!ft_verify_fdt(blob)) goto err;#if defined(CONFIG_SOC_KEYSTONE) if (IMAGE_OF_BOARD_SETUP) ft_board_setup_ex(blob, gd- >bd);#endif
return 0;err: printf(" - must RESET the board to recover.nn");
return ret;}这里我们只需要关注fdt_chosen函数，定义在common/fdt_support.c；其中rk3399和rk3588 SDK的u-boot源码是不一样的；以rk3588为例：int fdt_chosen(void *fdt){ int nodeoffset; int err; char*str; /* used to set string properties */
// 检查设备树头部是否有效 err = fdt_check_header(fdt); if (err < 0) { printf("fdt_chosen: %sn", fdt_strerror(err)); return err; }
/* find or create "/chosen" node.查找或创建/chosen节点 */ nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen"); if (nodeoffset < 0) return nodeoffset;
// 获取环境变量bootargs的值 str = board_fdt_chosen_bootargs(fdt); if (str) { // 设置设备树中的bootargs属性 err = fdt_setprop(fdt, nodeoffset, "bootargs", str, strlen(str) + 1); if (err < 0) { printf("WARNING: could not set bootargs %s.n", fdt_strerror(err)); return err; } }
return fdt_fixup_stdout(fdt, nodeoffset);}其中board_fdt_chosen_bootargs定义在arch/arm/mach-rockchip/board.c：char *board_fdt_chosen_bootargs(void *fdt){ /* bootargs_ext is used when dtbo is applied. */ const char *arr_bootargs[] = { "bootargs", "bootargs_ext" }; const char *bootargs; int nodeoffset; int i, dump; char *msg = "kernel";
/* debug */ hotkey_run(HK_INITCALL); dump = is_hotkey(HK_CMDLINE); if (dump) printf("## bootargs(u-boot): %snn", env_get("bootargs"));
/* find or create "/chosen" node. */ nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen"); if (nodeoffset < 0) return NULL;
// 遍历arr_bootargs，检查设备树中是否已有相关的bootargs for (i = 0; i < ARRAY_SIZE(arr_bootargs); i++) { // 获取/chosen节点的bootargs、bootargs_ext属性值 bootargs = fdt_getprop(fdt, nodeoffset, arr_bootargs, NULL); if (!bootargs) continue; if (dump) printf("## bootargs(%s-%s): %snn", msg, arr_bootargs, bootargs); /* * Append kernel bootargs * If use AB system, delete default "root=" which route * to rootfs. Then the ab bootctl will choose the * high priority system to boot and add its UUID * to cmdline. The format is "roo=PARTUUID=xxxx...". */#ifdef CONFIG_ANDROID_AB env_update_filter("bootargs", bootargs, "root=");#else // 进入，更新bootargs环境变量，追加设备树中配置的bootargs env_update("bootargs", bootargs);#endif }#ifdef CONFIG_VENDOR_FRIENDLYELEC // 针对FriendlyELEC板卡的处理，进入 char *panel = board_get_panel_name(); // 如果设置了panel，更新bootargs环境变量，比如追加lcd=HD702E,213dpi if (panel) { char lcdinfo = { 0 }; strcpy(lcdinfo, "lcd="); strncat(lcdinfo, panel, sizeof(lcdinfo) - 5); env_update("bootargs", lcdinfo); }#endif#if defined(CONFIG_ENVF) || defined(CONFIG_ENV_PARTITION) ......#endif#ifdef CONFIG_MTD_BLK ......#endif#ifdef CONFIG_ANDROID_AB ab_update_root_partition();#endif /* * Initrd fixup: remove unused "initrd=0x...,0x...", * this for compatible with legacy parameter.txt */ env_delete("bootargs", "initrd=", 0); /* * If uart is required to be disabled during * power on, it would be not initialized by * any pre-loader and U-Boot. * * If we don't remove earlycon from commandline, * kernel hangs while using earlycon to putc/getc * which may dead loop for waiting uart status. * (It seems the root cause is baundrate is not * initilalized) * * So let's remove earlycon from commandline. */ if (gd- >flags & GD_**_DISABLE_CONSOLE) env_delete("bootargs", "earlycon=", 0); /* Android header v4+ need this handle */#ifdef CONFIG_ANDROID_BOOT_IMAGE struct andr_img_hdr *hdr; hdr = (void *)env_get_ulong("android_addr_r", 16, 0); if (hdr && !android_image_check_header(hdr) && hdr->header_version >= 4) { if (env_update_extract_subset("bootargs", "andr_bootargs", "androidboot.")) printf("extract androidboot.xxx errorn"); if (dump) printf("## bootargs(android): %snn", env_get("andr_bootargs")); }#endif bootargs = env_get("bootargs"); if (dump) printf("## bootargs(merged): %snn", bootargs); return (char *)bootargs;}以rk3399为例：int fdt_chosen(void *fdt){ /* * "bootargs_ext" is used when dtbo is applied. */ const char *arr_bootargs[] = { "bootargs", "bootargs_ext" }; int nodeoffset; int err; int i; char*str; /* used to set string properties */ int dump; // 判断HK_CMDLINE是否是热键，返回false dump = is_hotkey(HK_CMDLINE); // 检查设备树头部是否有效 err = fdt_check_header(fdt); if (err < 0) { printf("fdt_chosen: %sn", fdt_strerror(err)); return err; } /* find or create "/chosen" node.查找或创建/chosen节点 */ nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen"); if (nodeoffset < 0) return nodeoffset; // 获取环境变量bootargs的值 str = env_get("bootargs"); if (str) {// 如果环境变量配置了bootargs#ifdef CONFIG_ARCH_ROCKCHIP // 针对Rockchip架构的处理 const char *bootargs; if (dump) printf("## U-Boot bootargs: %sn", str); // 遍历arr_bootargs，检查设备树中是否已有相关的bootargs for (i = 0; i < ARRAY_SIZE(arr_bootargs); i++) { // 获取/chosen节点的bootargs、bootargs_ext属性值 bootargs = fdt_getprop(fdt, nodeoffset, arr_bootargs, NULL); // 1. fdt_chosen 389:earlycon=uart8250,mmio32,0xff1a0000 swiotlb=1 coherent_pool=1m // 2. fdt_chosen 389:root=/dev/mmcblk2p8 rw rootfstype=ext4 rootflags=discard data=/dev/mmcblk2p9 console=ttyFIQ0 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 printf("%s %d:%sn", __func__, __LINE__, bootargs); // 如果存在，更新环境变量bootargs if (bootargs) { if (dump) printf("## Kernel %s: %sn", arr_bootargs, bootargs); /* * Append kernel bootargs * If use AB system, delete default "root=" which route * to rootfs. Then the ab bootctl will choose the * high priority system to boot and add its UUID * to cmdline. The format is "roo=PARTUUID=xxxx...". */ hotkey_run(HK_INITCALL);#ifdef CONFIG_ANDROID_AB // 未定义 env_update_filter("bootargs", bootargs, "root=");#else // 进入，更新bootargs环境变量，追加设备树中配置的bootargs env_update("bootargs", bootargs);#endif#ifdef CONFIG_MTD_BLK // 未定义 char *mtd_par_info = mtd_part_parse();
if (mtd_par_info) { if (memcmp(env_get("devtype"), "mtd", 3) == 0) env_update("bootargs", mtd_par_info); }#endif /* * Initrd fixup: remove unused "initrd=0x...,0x...", * this for compatible with legacy parameter.txt */ env_delete("bootargs", "initrd=", 0);
/* * If uart is required to be disabled during * power on, it would be not initialized by * any pre-loader and U-Boot. * * If we don't remove earlycon from commandline, * kernel hangs while using earlycon to putc/getc * which may dead loop for waiting uart status. * (It seems the root cause is baundrate is not * initilalized) * * So let's remove earlycon from commandline. */ if (gd- >flags & GD_**_DISABLE_CONSOLE) env_delete("bootargs", "earlycon=", 0); } }#endif
#ifdef CONFIG_VENDOR_FRIENDLYELEC // 针对FriendlyELEC板卡的处理，进入 char *panel = board_get_panel_name(); // 如果设置了panel，更新bootargs环境变量，比如追加lcd=HD702E,213dpi if (panel) { char lcdinfo = { 0 }; strcpy(lcdinfo, "lcd="); strncat(lcdinfo, panel, sizeof(lcdinfo) - 5); env_update("bootargs", lcdinfo); }#endif // 获取更新后的bootargs环境变量，并设置设备树中的bootargs属性 str = env_get("bootargs"); // fdt_chosen 451:storagemedia=emmc androidboot.storagemedia=emmc androidboot.mode=normal androidboot.dtbo_idx=0 earlycon=uart8250,mmio32,0xff1a0000 swiotlb=1 coherent_pool=1m rw root=/dev/mmcblk2p8 rootfstype=ext4 rootflags=discard data=/dev/mmcblk2p9 console=ttyFIQ0 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1 lcd=HD702E,213dpi printf("%s %d:%sn", __func__, __LINE__, str); err = fdt_setprop(fdt, nodeoffset, "bootargs", str, strlen(str) + 1); if (err < 0) { printf("WARNING: could not set bootargs %s.n", fdt_strerror(err)); return err; } }
if (dump) printf("## Merged bootargs: %sn", env_get("bootargs"));
return fdt_fixup_stdout(fdt, nodeoffset);}通过分析，可以了解到fdt_chosen 函数主要完成了以下任务：确保设备树的 /chosen 节点存在；从环境变量中获取和处理启动参数 bootargs；根据不同的硬件配置（如Rockchip架构或FriendlyELEC板卡）调整启动参数；更新设备树中的 bootargs 属性，确保内核可以正确获得启动参数；修正标准输出设备配置。在上面代码执行过程中我们输出了/chosen节点的bootargs、bootargs_ext属性值，其中bootargs_ext属性值哪里来的呢？root=/dev/mmcblk2p8 rw rootfstype=ext4 rootflags=discard data=/dev/mmcblk2p9 console=ttyFIQ0 consoleblank=0 cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1这个值实际上配置在dtbo.img镜像中，具体可以参考android_fdt_overlay_apply函数，这个我们在接下来的内容会介绍到。1.4 uboot编译和烧录1.4.1 编译如果我们对uboot源码有改动，执行如下命令进行编译；root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588# UBOOT_SRC=$PWD/uboot-rockchip ./build-uboot.sh debian-bullseye-desktop-arm64编译完成后debian-bullseye-desktop-arm64目录下的uboot.img被更新了。1.4.2dd烧录由于uboot.img占用的分区是uboot分区，假设SD/TF Card设备节点为/dev/mmcblk0。我们在ubuntu开启http下载服务，或者使用scp将镜像文件发送到开发版；root@ubuntu:/work/sambashare/rk3588/friendly/sd-fuse_rk3588/debian-bullseye-desktop-arm64$ python3 -m http.server 8080开发板下载uboot.img，然后使用如下命令烧录；root@linaro-alip:/opt# sudo wget 192.168.0.200:8080/uboot.imgroot@linaro-alip:/opt# sudo dd if=uboot.img of=/dev/mmcblk0p1 bs=1M同样如果我们修改了resource.img，也可以使用如下命令烧录；root@linaro-alip:/opt# sudo wget 192.168.0.200:8080/resource.imgroot@linaro-alip:/opt# sudo dd if=resource.img of=/dev/mmcblk0p4 bs=1M
主要硬件指标
CPUROCKCHIP RK3588 八核 A76+A55
NPU6 TOPS
GPUMali G61 MP4
DDRLPDDR4x 可选配 4G/8G/16G
EMMCEMMC 5.1 标配 8GB 选配 32G/64G/128G
工作电压3.4-5.5V 5A 以上
工作温度-10 到+60 度
连接方式板对板连接器
尺寸60mm 长*50mm 宽*4.2mm 高
寿命连续运行寿命大于 5 年以上
这个确实可以学一学，这种资料可以多分享分享 uboot环境变量的设置和使用在这篇文章中讲解得很清楚。这些环境变量在启动过程中起到了关键作用
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