Windows for Workgroups 3.11 fails to start with AMD PCNET device in qemu > 7.1.0 on Apple M1 hosts

Host environment

• Operating system: macOS Sequoia 15.5 (24F74)
• OS/kernel version: Darwin proton.ldx.ca 24.5.0 Darwin Kernel Version 24.5.0: Tue Apr 22 19:54:49 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6000 arm64
• Architecture: arm64
• QEMU flavor: qemu-system-i386
• QEMU version: 7.2.0 through qemu.git master
• QEMU command line:

  qemu-system-i386 -cpu 486 -m 16m \
       -rtc base=localtime \
       -hda wfw311-pcnet.qcow2 \
       -netdev user,id=n0 \
       -device pcnet,romfile=,netdev=n0,mac=52:54:00:61:6d:64 \
       -device vmware-svga

Emulated/Virtualized environment

• Operating system: Windows for Workgroups 3.11
• OS/kernel version: 3.11
• Architecture: i386 (-cpu 486)

Description of problem

I have two host systems: (1) an Apple M1 Pro (2021), and (2) an Apple MacBook Pro (Retina, Late 2013). I am using the same qemu command and disk image on both systems. I am using TCG on both systems.

On the M1 Pro (arm64) host, with an AMD PCNET device configured and its driver installed, when I launch win.com, the Windows 3.11 splash screen appears briefly, but then switches to the text mode console with a blinking cursor and nothing else happens. The system appears unresponsive (Ctrl-Alt-Del doesn’t work).

But the same qemu command on my MacBook Pro (x86_64) host works as expected: Windows launches, I can ping things, etc.

Steps to reproduce

1. On an Apple M1 system, launch qemu > 7.1.0 with a -device pcnet attached.
2. Install Windows for Workgroups 3.11, and install the AMD PCNET driver.
3. Reboot.
4. Launch win.com and notice that it hangs after the splash screen.

Additional information

I mention AMD PCNET, but it seems that any NIC I tried is affected. So far I tried ne2k_isa, ne2k_pci, rtl8139, pcnet.

On my M1 Pro, I compiled every minor qemu version from 6.2.0 to 10.0.2, plus the qemu.git master from today (9 June 2025), and tested.

• Working versions: 6.2.0, 7.0.0, 7.1.0
• Non-working versions: 7.2.0, 8.0.0, 8.1.0, 8.2.0, 9.0.0, 9.1.0, 9.2.0, 10.0.0, 10.0.2, qemu.git master

I didn’t test as extensively on my (working) MacBook Pro, but I can confirm that at least 9.2.0 works.

The changelog for 7.2.0 suggests some TCG changes were made which could be implicated, but I don’t know enough to understand whether it’s really the cause.

A working example from 7.1.0 (ignore the SVGA artifacting, I think it’s already fixed in some later release):

A non-working example:

I’m happy to do any other testing/diagnostics as required. And I can provide the qcow2 image if that would cut down on testing time.

(And yes, while this is a bit “niche”, affecting an ancient version of Windows, I figured it was still worth reporting in case it impacted anything else negatively, especially as it’s easy to reproduce.)