And the (SeaBIOS) winner is...
4a6dbcea3e412fe12effa2f812f50dd7eae90955 is the first bad commit
commit 4a6dbcea3e412fe12effa2f812f50dd7eae90955
Author: Nikolay Nikolov <nick...@users.sourceforge.net>
Date: Sun Feb 4 17:27:01 2018 +0200
floppy: Use timer_check() in floppy_wait_irq()
Use timer_check() instead of using floppy_motor_counter in BDA for the
timeout check in floppy_wait_irq().
The problem with using floppy_motor_counter was that, after it reaches
0, it immediately stops the floppy motors, which is not what is
supposed to happen on real hardware. Instead, after a timeout (like in
the end of every floppy operation, regardless of the result - success,
timeout or error), the floppy motors must be kept spinning for
additional 2 seconds (the FLOPPY_MOTOR_TICKS). So, now the
floppy_motor_counter is initialized to 255 (the max value) in the
beginning of the floppy operation. For IRQ timeouts, a different
timeout is used, specified by the new FLOPPY_IRQ_TIMEOUT constant
(currently set to 5 seconds - a fairly conservative value, but should
work reliably on most floppies).
After the floppy operation, floppy_drive_pio() resets the
floppy_motor_counter to 2 seconds (FLOPPY_MOTOR_TICKS).
This is also consistent with what other PC BIOSes do.
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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
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