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<think>
Okay, I need to figure out whether this QEMU error is a user-mode or system-mode issue. The user is trying to run a Cortex-M binary using qemu-arm 8.1.0 and getting an "Error mapping file: Operation not permitted" message.
First, let's look at what they did step by step. They wrote a simple C program, compiled it with arm-none-eabi-gcc targeting Cortex-M55, and then tried to run it with QEMU. The error occurs when QEMU tries to map the file into memory.
I remember that in user-mode emulation, QEMU runs programs as if they were on the host's CPU but under a different architecture. For ARM targets like Cortex-M, which is a microcontroller profile, sometimes special handling is needed because these are not full OS environments.
The error message suggests a permissions issue when mapping the file. Maybe there's something wrong with how QEMU handles Cortex-M binaries in newer versions. Since version 8.0.4 worked, it's possible that a change between 8.0.4 and 8.1.0 caused this problem.
Looking into QEMU's behavior, user-mode emulation typically deals with running executables directly without an OS. For Cortex-M, sometimes you need to specify the entry point or use specific arguments. Maybe in 8.1.0, there are new security measures that prevent certain mappings unless specific flags are set.
I also consider whether this is a system-mode issue, but system-mode usually involves emulating hardware and peripherals, which doesn't seem directly related here. The error is about mapping the file, which sounds more like user-mode where QEMU is trying to load the executable into its memory space.
So, putting it all together, the bug seems to be in how QEMU's user-mode emulation handles Cortex-M binaries in version 8.1.0, possibly a regression from 8.0.4.
</think>
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