In kgdb, I cannot set the breakpoint

Question

I'm using kgdb to debug the kernel.

I'm using qemu 2.11.0, and ubuntu 16.04.3 server version for guest.

I installed the kernel 4.16.0-rc6(mainline) and boot the guest os with this kernel with kgdb options(kgdbwait kgdboc=ttyS0,115200).

The gdb can connect to guest successfully.

However, setting a break point is fail with below error message.

Cannot access memory at address 0xffffffff8124b170

Actually, I used to debug the kernel with kgdb, and version of kernel is 4.8 below.

The kernel is in raw format virtual disk.

I compiled and installed this kernel in guest by mounting raw format virtual disk to guest, and open the vmlinux file with gdb by mounting raw format virtual disk to host.

Is there any fault?

Answer 1

I solved this problem.

It was because of KASLR.

This is solution.