So finally, the commit that introduced this regression is not directly related to QEMU:
0b8f74488e50f98b04e63157f85fde8a13f8d6aa is the first bad commit commit 0b8f74488e50f98b04e63157f85fde8a13f8d6aa Author: Gerd Hoffmann <kra...@redhat.com> Date: Tue Nov 6 12:23:53 2018 +0100 update seabios to master snapshot seabios 1.12 release is planned for november. update seabios to a master branch snapshot so it gets more testing and to make the delta smaller when updating to -final during freeze. -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1840719 Title: win98se floppy fails to boot with isapc machine Status in QEMU: New Bug description: QEMU emulator version 4.1.50 (commit 50d69ee0d) floppy image from: https://winworldpc.com/download/417d71c2-ae18-c39a-11c3-a4e284a2c3a5 $ qemu-system-i386 -M isapc -fda Windows\ 98\ Second\ Edition\ Boot.img SeaBIOS (version rel-1.12.1-0...) Booting from Floppy... Boot failed: could not read the boot disk To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1840719/+subscriptions