Okay, I need to figure out whether this bug report about QEMU is user-mode or system-mode related. The issue is that when following a tutorial on writing an OS (specifically the "Hello World" OS), it works on Ubuntu but dumps on macOS using QEMU. First, let me understand what's happening. The user is creating their own operating system and testing it with QEMU. On Ubuntu, everything goes fine, but on macOS, there's a crash or dump. So the problem occurs when running in a virtualized environment provided by QEMU on macOS. Now, thinking about QEMU itself. It can run in two main modes: user-mode and system-mode. User-mode emulation is when QEMU runs applications without emulating hardware, translating syscalls from one OS to another. System-mode, on the other hand, emulates an entire computer, including the BIOS, devices, and peripherals, which allows running full operating systems. In this case, since the user is trying to boot their own OS, they must be using QEMU in system-mode. They're likely not just running a single application but rather starting a virtual machine where their OS should run. The fact that it works on Ubuntu suggests that the issue isn't with the OS itself but perhaps how QEMU interacts with macOS. So why would it crash only on macOS? Maybe there are differences in how QEMU is compiled or runs on different host systems. Perhaps certain hardware emulations aren't handled correctly when running on macOS, leading to crashes during boot. Since the problem involves starting an OS and dealing with low-level system operations like booting and initializing hardware, this falls under system-mode. Additionally, since peripherals and device drivers are part of the QEMU setup in system-mode, any issues there would be system-related. The user isn't just running a userspace application; they're emulating a full system, which points towards a system-mode bug. system