This file will show the use of gdb to debugging binary kernel file.
Add -s -S flag along with Qemu Run i.e.
Open a ubuntu terminal and run
qemu-system-x86_64 -cdrom build/KeblaOS-0.11-image.iso -m 4096 -serial file:debug/serial_output.log -d guest_errors,int,cpu_reset -D debug/qemu.log -vga std -machine ubuntu -s -S
Now open another Ubuntu Terminal tab and run
gdb build/kernel.bin
Now in 2nd terminal tab run target remote:1234.
layout asm for see asm layout
break kmain to enter inside of kmain function
stepi to increase step inside of kmain function.
Suppos your kmain is look follow
void kmain(){
fun1();
fun2();
fun3();
}
You want to look inside of fun3() after running fun1() and fun2() then you need to run below commands
break fun3();
run
Now see below code to look inside of a specific address
(gdb) break *0x1000 # Break at address 0x1000
(gdb) break isr_common_stub # Break at the ISR common stub
(gdb) continue
(gdb) info registers
(gdb) next # step over function
(gdb) disassemble main
Set up rax with 0x1234 value
(gdb) set $rax = 0x1234
Setting 0x1000 pointer with value 0xdeadbeef
(gdb) set *(int*)0x1000 = 0xdeadbeef
To see the 0x1000 address
(gdb) x/4x 0x1000