ARM cpu emulation regression on QEMU 4.2.0
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
QEMU |
Expired
|
Undecided
|
Unassigned |
Bug Description
[*] Summary
Latest QEMU has an ARM CPU emulation regression.
Regression is reproducible by building any C# project with .NET Core SDK 3.1.300 on Debian 10 armhf guest OS.
Releases affected: QEMU 4.2.0, 5.0.0
Releases not affected: QEMU 4.1.0, QEMU 4.1.1
[*] Detail
.NET Core SDK 3.1 fails to run on Debian 10 emulated by qemu-system-arm.
I occasionally test my C# projects on the virtual armhf/arm64 system emulated by QEMU. MSBuild, a build engine of the .NET Core SDK, crashes on QEMU 4.2.0 or later. The crash only happens when MSBuild tries to do any JIT compiling (dotnet build / dotnet test).
I attached the MSBuild crash logs. MSBuild always crashes with SEHException, which means it tried to call C binary from .NET binary.
I think the ARM CPU emulation regression happened between QEMU 4.1.1 ~ 4.2.0. The issue affects QEMU 4.2.0 and 5.0.0. QEMU 4.1.0, 4.1.1, and real Raspberry Pi 2 are not affected by this issue, and .NET Core SDK works completely fine.
[*] Environment
[Host OS]
Distribution: Linux Mint 19.3 amd64
CPU: AMD Ryzen 5 3600
Kernel: Ubuntu 5.3.0-51-generic
[QEMU Guest OS]
Distribution: Debian 10 Buster armhf
Kernel: Debian 4.19.0-9-armmp-lpae
.NET Core SDK: 3.1.300
[Raspberry Pi 2]
Distribution: Raspberry Pi OS Buster armhf
Kernel: 4.19.118-v7+
[Tested C# Projects]
This is a list of C# projects I have tested on QEMU and RPI2.
- https:/
- https:/
- https:/
[QEMU Launch Arguments]
qemu-system-arm \
-smp 3 -M virt -m 4096 \
-kernel vmlinuz-
-initrd initrd.
-append "root=/dev/vda2" \
-drive if=none,
-device virtio-
-netdev user,id=
-device virtio-
-device virtio-rng-device
[QEMU Configure Arguments]
./configure --enable-spice --enable-gtk --enable-vnc-jpeg --enable-vnc-png --enable-avx2 --enable-libusb --enable-opengl --enable-
description: | updated |
description: | updated |
Changed in qemu: | |
status: | New → Confirmed |
I have tested 4.2.0 release candidate versions to pinpoint which commit caused the regression.
- 4.2.0-rc2: Same with 4.2.0, dotnet command crashes with SEHException.
- 4.2.0-rc0, 4.2.0-rc1: Launching dotnet command with any argument crashes with illegal hardware instruction message.
$ dotnet build
[1] 658 illegal hardware instruction dotnet build
$ dotnet --version
[1] 689 illegal hardware instruction dotnet --version
So the issue is affected by some commits pushed between 4.1.0 ~ 4.2.0-rc0 and 4.2.0-rc1 ~ 4.2.0-rc2 period.