Okay, so I'm trying to figure out whether this bug report is related to user-mode or system-mode in QEMU. Let me go through the information provided. The user is running AIX 7.2 TL4 SP1 using QEMU, specifically with ppc64-softmmu. They tried different versions of QEMU: version 4.2.93 (which is newer) and version 2.11.2 (older). The issue seems to be that when they use QEMU versions higher than 2.11.2, the system doesn't IPL (Initial Program Load), which means it can't boot properly. Looking at the commands provided, I see that when using QEMU 4.2.93 with either POWER8 or POWER9 CPUs, there's an error message about a failed assertion in cpus.c, specifically "qemu_tcg_cpu_thread_fn: assertion failed: (cpu->halted)". This indicates a problem during CPU initialization or execution. In the case of QEMU 2.11.2, they could successfully boot into AIX and log in as root. But with newer versions, it fails. The error message when using POWER9 shows some kernel panic logs and ends up halting. For POWER8, the system doesn't even reach the login prompt. I know that QEMU's ppc64 target involves emulating PowerPC processors, which is part of the hardware-level emulation. Issues during booting usually relate to lower-level functions like device initialization, CPU setup, or how the virtualized hardware interacts with the guest OS. The fact that older versions work but newer ones don't suggests a regression in QEMU's handling of certain features or configurations. Since AIX is an operating system that tightly integrates with hardware (especially on PowerPC), any changes in how QEMU emulates the CPU, memory management, or device drivers could cause such issues. The error message about "hcall-multi-tce detected but overridden" and subsequent kernel panic logs point towards problems in handling hypercalls or transactional consistency extensions (TCEs). These are low-level functions that affect how the guest OS interacts with virtualized hardware. The assertion failure in cpus.c is a critical issue during CPU thread function execution, which is definitely a system-mode problem. Considering all this, the bug is related to how QEMU emulates the PowerPC architecture at a low level, affecting the ability of the AIX kernel to boot correctly. This involves device handling, CPU state management, and possibly memory emulation—elements that are part of the system-mode operations in QEMU. system