Okay, I'm trying to figure out whether this bug report is related to user-mode or system-mode in QEMU. The issue describes a crash when executing `ucomiss` instructions while emulating an x86-64 CPU on an AArch64 host. First, I need to understand what each mode entails. User-mode emulation typically deals with running applications and translating their instructions without involving the full OS or hardware devices. System-mode, on the other hand, involves higher privileges, device emulation, peripherals, and the entire operating system. The `ucomiss` instruction is an x86 floating-point comparison instruction used in user-space applications. Since it's about executing a specific CPU instruction during emulation, this seems to relate more to how QEMU handles user-level instructions rather than system-level operations like OS interactions or device handling. Therefore, the bug is likely related to user-mode. user