On 8/20/19 3:12 PM, John Snow wrote: > On 8/20/19 6:25 AM, Philippe Mathieu-Daudé wrote: >> [cross posting QEMU & SeaBIOS] >> >> Hello, >> >> I'v been looking at a QEMU bug report [1] which bisection resulted in a >> SeaBIOS commit: >> >> 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. >> >> >> This commit improve behavior with real hardware, so maybe QEMU is not >> modelling something or modelling it incorrectly? [...] > > Well, that's unfortunate. > > What version of QEMU shipped the SeaBIOS that caused the regression?
See https://bugs.launchpad.net/qemu/+bug/1840719/comments/3 QEMU commit 0b8f74488e, slighly before QEMU v3.1.0 (previous tag is v3.0.0). But you can use v4.1.0 too, simply change the SeaBIOS bios.bin, i.e.: qemu$ git checkout v4.1.0 qemu$ (cd roms/seabios && git checkout 4a6dbcea3e4~) && \ make -C roms bios Now pc-bios/bios.bin is built using the last commit working, qemu$ (cd roms/seabios && git checkout 4a6dbcea3e4) && \ make -C roms bios And you can reproduce the error. Regards, Phil.