uboot的相关知识，可以参考：uboot基本概念。
一、环境配置
WSL: ubutu20.04
模拟开发板：vexpress-a9
uboot版本：u-boot-2023.10
二、安装QEMU
- 2.1、安装
sudo apt install qemu - 2.2、查看支持哪些开发板
结果如下：qemu-system-arm -M helpSupported machines are: akita Sharp SL-C1000 (Akita) PDA (PXA270) ast2500-evb Aspeed AST2500 EVB (ARM1176) ast2600-evb Aspeed AST2600 EVB (Cortex A7) borzoi Sharp SL-C3100 (Borzoi) PDA (PXA270) canon-a1100 Canon PowerShot A1100 IS cheetah Palm Tungsten|E aka. Cheetah PDA (OMAP310) collie Sharp SL-5500 (Collie) PDA (SA-1110) connex Gumstix Connex (PXA255) cubieboard cubietech cubieboard (Cortex-A8) emcraft-sf2 SmartFusion2 SOM kit from Emcraft (M2S010) highbank Calxeda Highbank (ECX-1000) imx25-pdk ARM i.MX25 PDK board (ARM926) integratorcp ARM Integrator/CP (ARM926EJ-S) kzm ARM KZM Emulation Baseboard (ARM1136) lm3s6965evb Stellaris LM3S6965EVB lm3s811evb Stellaris LM3S811EVB mainstone Mainstone II (PXA27x) mcimx6ul-evk Freescale i.MX6UL Evaluation Kit (Cortex A7) mcimx7d-sabre Freescale i.MX7 DUAL SABRE (Cortex A7) microbit BBC micro:bit midway Calxeda Midway (ECX-2000) mps2-an385 ARM MPS2 with AN385 FPGA image for Cortex-M3 mps2-an505 ARM MPS2 with AN505 FPGA image for Cortex-M33 mps2-an511 ARM MPS2 with AN511 DesignStart FPGA image for Cortex-M3 mps2-an521 ARM MPS2 with AN521 FPGA image for dual Cortex-M33 musca-a ARM Musca-A board (dual Cortex-M33) musca-b1 ARM Musca-B1 board (dual Cortex-M33) musicpal Marvell 88w8618 / MusicPal (ARM926EJ-S) n800 Nokia N800 tablet aka. RX-34 (OMAP2420) n810 Nokia N810 tablet aka. RX-44 (OMAP2420) netduino2 Netduino 2 Machine none empty machine nuri Samsung NURI board (Exynos4210) palmetto-bmc OpenPOWER Palmetto BMC (ARM926EJ-S) raspi2 Raspberry Pi 2 realview-eb ARM RealView Emulation Baseboard (ARM926EJ-S) realview-eb-mpcore ARM RealView Emulation Baseboard (ARM11MPCore) realview-pb-a8 ARM RealView Platform Baseboard for Cortex-A8 realview-pbx-a9 ARM RealView Platform Baseboard Explore for Cortex-A9 romulus-bmc OpenPOWER Romulus BMC (ARM1176) sabrelite Freescale i.MX6 Quad SABRE Lite Board (Cortex A9) smdkc210 Samsung SMDKC210 board (Exynos4210) spitz Sharp SL-C3000 (Spitz) PDA (PXA270) swift-bmc OpenPOWER Swift BMC (ARM1176) sx1 Siemens SX1 (OMAP310) V2 sx1-v1 Siemens SX1 (OMAP310) V1 terrier Sharp SL-C3200 (Terrier) PDA (PXA270) tosa Sharp SL-6000 (Tosa) PDA (PXA255) verdex Gumstix Verdex (PXA270) versatileab ARM Versatile/AB (ARM926EJ-S) versatilepb ARM Versatile/PB (ARM926EJ-S) vexpress-a15 ARM Versatile Express for Cortex-A15 vexpress-a9 ARM Versatile Express for Cortex-A9 virt-2.10 QEMU 2.10 ARM Virtual Machine virt-2.11 QEMU 2.11 ARM Virtual Machine virt-2.12 QEMU 2.12 ARM Virtual Machine virt-2.6 QEMU 2.6 ARM Virtual Machine virt-2.7 QEMU 2.7 ARM Virtual Machine virt-2.8 QEMU 2.8 ARM Virtual Machine virt-2.9 QEMU 2.9 ARM Virtual Machine virt-3.0 QEMU 3.0 ARM Virtual Machine virt-3.1 QEMU 3.1 ARM Virtual Machine virt-4.0 QEMU 4.0 ARM Virtual Machine virt-4.1 QEMU 4.1 ARM Virtual Machine virt QEMU 4.2 ARM Virtual Machine (alias of virt-4.2) virt-4.2 QEMU 4.2 ARM Virtual Machine witherspoon-bmc OpenPOWER Witherspoon BMC (ARM1176) xilinx-zynq-a9 Xilinx Zynq Platform Baseboard for Cortex-A9 z2 Zipit Z2 (PXA27x)
三、安装交叉编译链
sudo apt install arm-linux-gnueabi-gcc
注：此步非必须，也可自己从Arm GNU Toolchain下载，解压后添加到环境变量即可。
四、编译uboot
- 4.1、解压
tar -vxjf u-boot-2023.10.tar.bz2
- 4.2、编译
cd u-boot-2023.10/make ARCH=arm CROSS_COMPLIE=arm-none-linux-gnueabihf- vexpress_ca9x4_defconfig
make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabihf- -j`nproc`
- 4.3、生成的u-boot.bin文件
五、使用qemu工具运行uboot
- 5.1、启动uboot
qemu-system-arm -M vexpress-a9 -m 512M -kernel ./u-boot -nographic -no-reboot
运行结果如下：
U-Boot 2023.10 (Nov 02 2023 - 10:17:15 +0800)DRAM: 512 MiB
WARNING: Caches not enabled
Core: 18 devices, 10 uclasses, devicetree: embed
Flash: 64 MiB
MMC: mmci@5000: 0
Loading Environment from Flash... *** Warning - bad CRC, using default environmentIn: serial
Out: serial
Err: serial
Net: eth0: ethernet@3,02000000
Hit any key to stop autoboot: 0
MMC Device 1 not found
no mmc device at slot 1
Card did not respond to voltage select! : -110
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
BOOTP broadcast 1
DHCP client bound to address 10.0.2.15 (2 ms)
*** Warning: no boot file name; using '0A00020F.img'
Using ethernet@3,02000000 device
TFTP from server 10.0.2.2; our IP address is 10.0.2.15
Filename '0A00020F.img'.
Load address: 0x60100000
Loading: *
TFTP error: 'Access violation' (2)
Not retrying...
smc911x: MAC 52:54:00:12:34:56
missing environment variable: pxefile_addr_r
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
BOOTP broadcast 1
DHCP client bound to address 10.0.2.15 (0 ms)
Using ethernet@3,02000000 device
TFTP from server 10.0.2.2; our IP address is 10.0.2.15
Filename 'boot.scr.uimg'.
Load address: 0x60100000
Loading: *
TFTP error: 'Access violation' (2)
Not retrying...
smc911x: MAC 52:54:00:12:34:56
smc911x: detected LAN9118 controller
smc911x: phy initialized
smc911x: MAC 52:54:00:12:34:56
BOOTP broadcast 1
DHCP client bound to address 10.0.2.15 (0 ms)
Using ethernet@3,02000000 device
TFTP from server 10.0.2.2; our IP address is 10.0.2.15
Filename 'boot.scr.uimg'.
Load address: 0x60100000
Loading: *
TFTP error: 'Access violation' (2)
Not retrying...
smc911x: MAC 52:54:00:12:34:56
cp - memory copyUsage:
cp [.b, .w, .l, .q] source target count
Wrong Image Format for bootm command
ERROR: can't get kernel image!
=>
说明uboot已经启动成功。
- 5.2、在uboot中输入help，查看uboot中的支持的命令：
=>
=> help
? - alias for 'help'
base - print or set address offset
bdinfo - print Board Info structure
blkcache - block cache diagnostics and control
bootefi - Boots an EFI payload from memory
bootelf - Boot from an ELF image in memory
bootflow - Boot flows
bootm - boot application image from memory
bootp - boot image via network using BOOTP/TFTP protocol
bootvx - Boot vxWorks from an ELF image
bootz - boot Linux zImage image from memory
cmp - memory compare
cp - memory copy
crc32 - checksum calculation
dhcp - boot image via network using DHCP/TFTP protocol
echo - echo args to console
eficonfig - provide menu-driven UEFI variable maintenance interface
env - environment handling commands
erase - erase FLASH memory
exit - exit script
ext2load - load binary file from a Ext2 filesystem
ext2ls - list files in a directory (default /)
ext4load - load binary file from a Ext4 filesystem
ext4ls - list files in a directory (default /)
ext4size - determine a file's size
false - do nothing, unsuccessfully
fatinfo - print information about filesystem
fatload - load binary file from a dos filesystem
fatls - list files in a directory (default /)
fatmkdir - create a directory
fatrm - delete a file
fatsize - determine a file's size
fatwrite - write file into a dos filesystem
fdt - flattened device tree utility commands
flinfo - print FLASH memory information
fstype - Look up a filesystem type
fstypes - List supported filesystem types
go - start application at address 'addr'
help - print command description/usage
iminfo - print header information for application image
ln - Create a symbolic link
load - load binary file from a filesystem
loop - infinite loop on address range
ls - list files in a directory (default /)
md - memory display
mii - MII utility commands
mm - memory modify (auto-incrementing address)
mmc - MMC sub system
mmcinfo - display MMC info
mw - memory write (fill)
net - NET sub-system
nm - memory modify (constant address)
panic - Panic with optional message
part - disk partition related commands
ping - send ICMP ECHO_REQUEST to network host
printenv - print environment variables
protect - enable or disable FLASH write protection
pxe - commands to get and boot from pxe files
To use IPv6 add -ipv6 parameter
random - fill memory with random pattern
reset - Perform RESET of the CPU
run - run commands in an environment variable
save - save file to a filesystem
saveenv - save environment variables to persistent storage
setenv - set environment variables
showvar - print local hushshell variables
size - determine a file's size
source - run script from memory
sysboot - command to get and boot from syslinux files
test - minimal test like /bin/sh
tftpboot - load file via network using TFTP protocol
true - do nothing, successfully
ubi - ubi commands
ubifsload - load file from an UBIFS filesystem
ubifsls - list files in a directory
ubifsmount- mount UBIFS volume
ubifsumount- unmount UBIFS volume
version - print monitor, compiler and linker version
=>
六、使用gdb调试uboot
- 6.1、输入如下启动命令：
qemu-system-arm -M vexpress-a9 -m 512M -kernel ./u-boot -nographic -no-reboot -S -s
其中：
-S 表示QEMU虚拟机会冻结CPU，直到远程的GDB输入相应的控制命令。
-s 表示在1234端口接收GDB调试连接。
- 6.2、gdb调试
重新打开一个终端，进入到u-boot文件的目录下，输入以下命令开始gdb调试：
cd u-boot-2023.10
gdb-multiarch --tui u-boot
如下：
- 6.3、开始调试
在gdb中输入以下命令，开始调试：
(gdb) set architecture arm
(gdb) target remote localhost:1234
以上，设置架构为arm架构，通过远程端口1234连接QEMU虚拟机。如下图：
上图显示，已经进入vectors.S文件中的_start程序入口。
接下来就可以单步跟踪调试了：
