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<think>
Okay, I need to classify this bug report as either user-mode or system-mode related. Let me read through the details carefully.
The problem occurs when running an x86_64 emulation on an aarch64 host using QEMU. The error messages mention issues in `cpu_exec` and `rcu_read_unlock`, which are parts of QEMU's code. The user is using systemd-nspawn to create an Ubuntu container and runs qemu-x86_64-static via binfmt.
The crash happens when executing commands like apt-get, but not ls. This suggests that it's related to more complex operations rather than simple file listings. The issue specifically doesn't occur on VMs under macOS, even with the same binaries and setup.
Asahi Linux is mentioned, which runs on an M1 Macbook Pro. These are big.LITTLE chips with a 16K page size, known to cause issues for some programs. However, qemu-arm-static works fine, implying that the problem isn't with ARM emulation but specifically x86_64.
Looking at the error messages:
- The first is an assertion failure in `cpu_exec` which checks if `cpu == current_cpu`. This suggests a concurrency or scheduling issue within QEMU's execution loop.
- The second error, when recompiling with clang, is about RCU (Read-Copy-Update) read unlock. It asserts that the depth isn't zero, indicating improper use of RCU primitives.
These errors point to internal issues in QEMU's user-mode emulation rather than system-level problems like hardware access or device drivers. Since it's happening during CPU execution and RCU handling, which are part of the emulator's core logic, it's likely a user-mode issue.
Additionally, since the problem occurs when running under binfmt (which typically uses user-mode QEMU) and not in a VM environment where system-level virtualization is handled differently, this supports that it's a user-mode bug.
</think>
user
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