How do I catch the cause of my x86 CPU reset?

I'm running Linux on QEMU emulating an x86_64 CPU. I'm attempting to Kexec into an elf32-format kernel, but after executing the the kernel, the system reboots and I'm not sure how to figure out why.

I attach GDB and can confirm that the new kernel is loaded properly and begins executing. I set a HW breakpoint after the new kernel sets up a new IDT and I put breakpoints on all the vectors to try and catch whatever exception might be getting raised (triple-fault reset) but nothing seems to hit.

Apart from deliberate reboot techniques (FAR JMP 0xFFFF:0000 ...etc), is there anything else that could be causing the CPU to reset that I'm missing?

Thanks.

Solution

The main way to do this would be to at the following flags to your QEMU call

-d int causes QEMU to display interrupts on error
-no-reboot will make it so that your machine won’t reboot
-no-shutdown same as -no-reboot

Also, the reason that your QEMU is rebooting is probably a Segmentation Fault.