Okay, so I'm trying to classify this bug report into one of the given categories: instruction, syscall, or runtime. Let's see what each category means. The problem is about the fmopa instruction in AArch64 not generating default NaNs correctly when using the 32-bit variant. The user provided code snippets showing that instead of getting a default NaN (0x7fc00000), they're getting 0xffffffff, which isn't the standard NaN. Looking at the code, there's an issue in the helper function for SME instructions. Specifically, the float_status pointer is being passed incorrectly to the multiplication function. The comment says that &fpst should be used instead of vst. So it looks like a bug in how the instruction is handled during execution. Since this is about the implementation and handling of an ARM instruction (fmopa) within QEMU's emulator, I think it falls under the "instruction" category. It's not related to syscalls or runtime errors but rather incorrect processing of a specific instruction. instruction