Qemu simulates gdb debugging of ARM

Qemu simulates gdb debugging of ARM

System: Ubuntu16.04.4 32bit
Cross Compiler: arm-linux-gnueabihf-gcc
VMware: VMware Workstation 14 Pro
u-boot: u-boot-2018.03
linux: linux-4.16.2

1. Debug uboot

qemu-system-arm -M vexpress-a9 -m 256M -nographic -kernel u-boot -gdb tcp::2233 -S

Stuck here waiting to connect
Host gdb connection

arm-linux-gnueabihf-gdb u-boot

Enter the command to connect to remote debugging

(gdb) target remote : 2233

2. Debug linux

The operation is the same as debugging uboot

qemu-system-arm -M vexpress-a9 -m 256M -nographic -kernel vmlinux -gdb tcp::2233 -S

arm-linux-gnueabihf-gdb vmlinux 

(gdb) target remote : 2233

3. gdb simple debugging command

next(n): the next part

step(s): step into

bt List function stack frames

print to view the value of a variable or memory

break line number or function name: next breakpoint

info breakpoints View current breakpoint information

delete clears all breakpoints

continue (c) run to the next breakpoint

print /x var hexadecimal display (var) value
print can specify the display format, where '/x' is used to represent the hexadecimal format.
The supported variable display formats are:
x Displays the variable in hexadecimal format.
d Displays variables in decimal format.
u Displays unsigned integers in hexadecimal format.
o Display variables in octal format.
t Display variables in binary format.
a Displays the variable in hexadecimal format.
c Displays variables in character format.
f Displays variables in floating-point format.

print x=4 Modify the variable value at runtime