id = 2794
title = "qemu-system-m68k virt machine doesn't boot Linux kernels using 68020, 68030 and 68060 CPUs"
state = "opened"
created_at = "2025-01-27T14:02:52.503Z"
closed_at = "n/a"
labels = ["target: m68k"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2794"
host-os = "FreeBSD"
host-arch = "amd64"
qemu-version = "QEMU emulator version 9.2.0"
guest-os = "Linux"
guest-arch = "m68k"
description = """QEMU doesn't seem to be able to start Linux kernels using a CPU other than a 68040 (which does work fine)

To rule out host issues, the issue is reproductible on Debian Unstable amd64 (with version QEMU emulator version 9.2.0)(Debian 1:9.2.0+ds-5))

To rule out cross-compilation issues, the kernel has been rebuild inside a virt machine (using a 68040 CPU), running Debian Unstable 

Each CPU model below gets stuck early before kernel boot during the ABCGHIJK thing. The Kernel doesn't seem to boot and QEMU process eat 100% of a CPU physical core

**68020**
```
qemu-system-m68k -M virt -cpu m68060 -m 1G -nographic -kernel /home/demik/tmp/vmlinux
ABCGH
```

**68030**
```
qemu-system-m68k -M virt -cpu m68060 -m 1G -nographic -kernel /home/demik/tmp/vmlinux
ABC
```

**68060**
```
qemu-system-m68k -M virt -cpu m68060 -m 1G -nographic -kernel /home/demik/tmp/vmlinux
ABC
```"""
reproduce = """1. build a kernel with 68020/030/060 support (using virt_defconfig as base)
2. start QEMU with the command line above"""
additional = """68020 is understandable as it may need some sort of 68851 emulation.

Relevant Kernel config Processor configuration:
```
#
# Processor Type
#
CONFIG_M68KCLASSIC=y
# CONFIG_COLDFIRE is not set
CONFIG_M68020=y
CONFIG_M68030=y
CONFIG_M68040=y
CONFIG_M68060=y
```

This may be related to the following issues (but I don't have the skillset to confirm that)
- https://gitlab.com/qemu-project/qemu/-/issues/2091
- https://gitlab.com/qemu-project/qemu/-/issues/2500"""