I was trying to debug an embedded OS using QEMU and GDB. The OS required Multiboot, so I was launching it from GRUB.
The problem was that I was unable to setup breakpoins in any of the OS code (either software or hardware breakpoints).
I fixed the problem by removing -enable-kvm from my QEMU command line. I was thinking wiki page should be updated, especially since I couldn't find this solution online.
I can gladly update qemu wiki page, unfortunately registering has been disabled. If somebody can add an account for me (username "neduard" or "eddnicodei") that would be appreciated. Alternatively they can update wiki themselves with something like:
"Please note that you should DISABLE KVM when doing system debugging with QEMU, failure to do so, might cause problems when setting up breakpoints."
"Also note, if debugging early bootup code in x86, you should be aware of the 'set architecture' gdb command".