Well.. This makes sense actually. At least this sounds true.
On Sat, Nov 15, 2025 at 2:04 PM Ramiro Aceves <[email protected]> wrote: > > > > El 15/11/25 a las 9:52, Vitaly Shevtsov escribió: > > Hello, Ramiro. > > > > I don't know the reason. It looks like FreeDOS uses something that > > other OSes don't use causing QEMU to crash. > > But for me it happens only when FreeDOS is being installed. Once it's > > installed I never face this issue. I'm pretty sure it's a bug in NVMM. > > Maybe it's worth trying dosbox instead? > > Hi Vitaly! > > dosbox works fine but it is a different thing, you know... > I have been several hour fighting with this, Chatgpt says the following > but I cannot trust him ;-) > > "NVMM’s early implementations had — and still have — some rough edges in > handling certain 16-bit BIOS calls or transitions between real mode and > protected mode." > > FreeDOS wants to boot in 16-bit real mode and use old hardware > peripherals (keyboard controller, PIT timer, SB16 sound card). > > QEMU normally emulates all of that correctly. > > NVMM, however, is designed for modern x86-64 virtualization, and it > cannot execute a VCPU correctly while it is in 16-bit real mode. > > Result: > QEMU aborts with “Failed to execute a VCPU.” > > I do not know if it is true or not, many times Chatgpt say silly things ;-) > > > Regards. > Ramiro. > > > > > > On Thu, Nov 13, 2025 at 11:29 PM Ramiro Aceves <[email protected]> wrote: > >> > >> > >> > >> El 13/11/25 a las 19:19, Vitaly Shevtsov escribió: > >>> Hello. I faced the same issue with qemu, nvmm and freedos. Tried to > >>> debug with no luck. I found a workaround - run qemu with no > >>> acceleration, install freedos, then run it with acceleration turned on. > >>> This issue only happens when is it is being installed. > >>> > >>> чт, 13 нояб. 2025 г., 23:15 Ramiro Aceves <[email protected] > >>> <mailto:[email protected]>>: > >>> > >>> > >>> Hello, > >>> > >>> I tried to install FreeDOS under Qemu in NetBSD 10.1 using nvmm > >>> acceleration driver. > >>> > >>> > >>> I get an error like this when almost installed on the virtual disk: > >>> > >>> qemu-system-i386: NVMM: Unexpected VM exit code 0xffffffffffffffff > >>> [hw=0x9] > >>> qemu-system-i386: NVMM: Failed to execute a VCPU. > >>> [1] Abort trap (core dumped) qemu-system-i386 -m 64 -accel nvmm - > >>> smp 1 > >>> -dri... > >>> > >>> > >>> I removed nvmm acceleration and I was able to end the installation > >>> without acceleration but it was painly slow. > >>> > >>> I have been able to virtualize a full Debian GNU/Linux system using > >>> nvmm, no problems at all. Why nvmm fails with FreeDOS? > >>> > >>> Thanks so much. > >>> Ramiro. > >>> > >> > >> Hello Vitaly, > >> > >> I have started the virtual FreeDOS with nvmm, it starts fast and well. > >> > >> > >> c:\dir (file listing works fine) > >> > >> But when I start an editor: > >> > >> > >> c:\EDIT > >> > >> qemu-system-i386: NVMM: Failed to execute a VCPU. > >> [1] Abort trap (core dumped) qemu-system-i386 -m 64 -accel nvmm -smp 1 > >> -dri... > >> netbsd-nuc$ > >> > >> > >> Regards. > >> Ramiro. > >> > >> > >>> > >>> > >> >
