Re: Using ubuntu24.4 system qemu-system-aarch64 +gdb-multiarch to debug the kernel, setting breakpoints cannot be stopped

On Mon, 2024-09-23 at 22:36 +0800, jie ren wrote:
> Hi, I have a question for help
>     I recently  Using ubuntu24.4 system qemu-system-aarch64 +gdb-
> multiarch to debug the kernel, setting breakpoints cannot be stopped.
>    system information:
>         ubuntu version: 22.04
>         Debug kernel version:  5.0.0
>         qemu version:  
> · qemu-system-aarch64 --version
> · QEMU emulator version 8.2.2 (Debian 1:8.2.2+ds-0ubuntu1.2)
> · Copyright (c) 2003-2023 Fabrice Bellard and the QEMU Project
> developers
>  
> 
>  
> gdb version:
> · gdb-multiarch --version
> · GNU gdb (Ubuntu 15.0.50.20240403-0ubuntu1) 15.0.50.20240403-git
> · Copyright (C) 2024 Free Software Foundation, Inc.
> · License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> · This is free software: you are free to change and redistribute it.
> · There is NO WARRANTY, to the extent permitted by law.
> 
> Steps to reproduce:
>     1. Boot the system using qemu:   
> 1. qemu-system-aarch64 -machine virt -cpu cortex-a57 -machine
> type=virt -m 1024 -smp 4 -kernel arch/arm64/boot/Image --append
> "noinitrd root=/dev/vda rw console=ttyAMA0 loglevel=8" -nographic -
> drive if=none,file=rootfs_ext4.img,id=hd0 -device virtio-blk-
> device,drive=hd0 --fsdev
> local,id=kmod_dev,path=$PWD/kmodules,security_model=none -device
> virtio-9p-device,fsdev=kmod_dev,mount_tag=kmod_mount -S -s
>  
> 
> Use gdb-multiarch to connect and debug:
> 
>  
> gdb-multiarch vmlinux
> (gdb) target remote localhost:1234
> Remote debugging using localhost:1234
> 0x0000000040000000 in ?? ()
> (gdb) b start_kernel
> Breakpoint 1 at 0xffff2000126704ec: file init/main.c, line 538.
> (gdb) c
> Continuing.

I would try using the "nokaslr" kernel option:

$ qemu-system-aarch64 -kernel ./Image.custom -M virt -cpu cortex-a57 -
append "console=ttyAMA0 nokaslr" -s -S -nographic

$ gdb-multiarch -ex 'target remote :1234' vmlinux

Remote debugging using :1234
0x0000000040000000 in ?? ()
(gdb) b start_kernel
Breakpoint 1 at 0xffff8000811e0968: file init/main.c, line 905.
(gdb) c
Continuing.

Breakpoint 1, start_kernel () at init/main.c:905
905             char *command_line;