qemu-system-i386 no longer boots NetBSD

Host environment

• Operating system: Debian 12
• OS/kernel version: Linux gumbo 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 (2024-02-01) x86_64 GNU/Linux
• Architecture: amd64
• QEMU flavor: qemu-system-i386
• QEMU version: QEMU emulator version 9.1.50 (v9.1.0-1334-gdaaf51001a)
• QEMU command line: qemu-system-i386 -cdrom NetBSD-10.0-i386.iso

Emulated/Virtualized environment

• Operating system: NetBSD
• OS/kernel version: 10.0
• Architecture: i386

Description of problem

Since qemu commit b56617bb, qemu-system-i386 can no longer boot NetBSD.

Steps to reproduce

wget https://cdn.netbsd.org/pub/NetBSD/NetBSD-10.0/images/NetBSD-10.0-i386.iso
qemu-system-i386 -cdrom NetBSD-10.0-i386.iso

Expected behavior: Boots into the NetBSD installer

Observed incorrect behavior: Boot hangs with a black screen

Additional information

This regression is a critical issue to the NetBSD project as its automated testing infrastructure is heavily dependent on qemu-system-i386.