Hello and thank you for letting me write in those forums!
I am currently using version 6.1 of VirtualBox on a Linux host with the QT5 frontend. I just installed a vm and deactivated VT-x (using Intel). However, even if I uncheck it from the virtualization tab, it keeps using it. Tried to deactivate virtualization acceleration from the BIOS, but all I get is an error stating that VT-x is deactivated from the host but virtualization is enabled (the option now appears unchecked and greyed off).
I never had this problem with previous versions, so I am quite sure it is a bug: The process is the same and I have done it hundreds of times in the past. Is there any way of FORCING to deactivate VT-x without the GUI if needed?
Thanks in advance
[FIXED] Option to uncheck VT-x acceleration is ignored. W9x guest
[FIXED] Option to uncheck VT-x acceleration is ignored. W9x guest
Last edited by vlad86 on 3. May 2020, 12:02, edited 3 times in total.
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Re: (possible bug) Option to uncheck VT-x acceleration is ignored
Actually it's not a bug but a new requirement: Virtualbox 6.1.x requires the host to have VT-x/AMD-V/SVM turned on in the BIOS for all guests regardless of previous need, and the ability to turn off VT-x et al for the guest environment was removed.
If there is some guest requirement that needs no VT-x in the guest (in other words you need that little checkbox that isn't there anymore) you need to downgrade to 6.0.x or earlier. You may be able to re-upgrade to 6.1.x after the step requiring no VT-x is complete. (There may be a particular need to not have VT-x on in the guest when installing Windows 95/98/ME, which were unsupported guests anyway. There may be other scenarios.)
If there is some guest requirement that needs no VT-x in the guest (in other words you need that little checkbox that isn't there anymore) you need to downgrade to 6.0.x or earlier. You may be able to re-upgrade to 6.1.x after the step requiring no VT-x is complete. (There may be a particular need to not have VT-x on in the guest when installing Windows 95/98/ME, which were unsupported guests anyway. There may be other scenarios.)
Re: (possible bug) Option to uncheck VT-x acceleration is ignored
scottgus1 wrote:Actually it's not a bug but a new requirement: Virtualbox 6.1.x requires the host to have VT-x/AMD-V/SVM turned on in the BIOS for all guests regardless of previous need, and the ability to turn off VT-x et al for the guest environment was removed.
If there is some guest requirement that needs no VT-x in the guest (in other words you need that little checkbox that isn't there anymore) you need to downgrade to 6.0.x or earlier. You may be able to re-upgrade to 6.1.x after the step requiring no VT-x is complete. (There may be a particular need to not have VT-x on in the guest when installing Windows 95/98/ME, which were unsupported guests anyway. There may be other scenarios.)
Tank you for the reply! true, I was trying to use Windows 95. What you say is quite disturbing, considering there isn't any other option that lets you decently emulate a DOS/W9x guest. It is true that I could downgrade for the moment, but that would be impossible to do in the future, as older versions get pulled down and/or libraries become too incompatible to run 6.0 or downwards, so that would be just a temporal solution.
How come that was decision was taken? Do you know any other VM software that would work? Basically I NEED to be able to run w9x, Those have been my pitfalls:
VMware: Paid software, recent versions doesn't even properly support OPL3 and bugs out the MIDI sound.
Qemu: Slow, sb16 has been broken for years now and freezes every few seconds with sound. AC97 drivers won't work as they used in virualbox
PCEm: Too slow to be practical My 8th gen Intel CPU runs the emulation at a 286 speed.
DosBox: Apart of never being able to install, if it worked for me it would lack the ability to mount and dismount ISO images on the fly.
I am running out of ideas here...
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Re: (possible bug) Option to uncheck VT-x acceleration is ignored
It's quite disturbing to me that this nonsense is still being proliferated many years after it was investigated and debunked. You do not need to turn off VT-x for a Win9x guest, and you never needed to do that. Win95 was always completely oblivious to VT-x being on or off, it doesn't use any of the features affected by it. OTOH with VT-x enabled it will benefit from the improved ability to catch nasty errors, such as running corrupted driver code.vlad86 wrote:What you say is quite disturbing, considering there isn't any other option that lets you decently emulate a DOS/W9x guest.
So you know, I maintain a set of "nostalgia" VMs, which are old DOS, Win 3.1, Win9x, NTx and Vista VMs. I've been running these as tests on every version of VirtualBox since 3.0.x something, which is when I started using it. Also my PC has changed several times in the intervening years. While there has occasionally been a bug that affected one or more VMs, none had anything to do with VT-x, and none lasted beyond the next monthly update.
See below, Windows 3.1 running under VirtualBox 6.1.6 on a Win10-64bit host with VT-x enabled. I showed a Win98SE guest a couple of weeks ago, which was the last time this crap came up, so I'm trying to mix things up a bit here.
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Re: (possible bug) Option to uncheck VT-x acceleration is ignored
Hey. Yeah, I actually think I had back in the day a Win 3.x vm with VT-x, so that is interesting. Haven't tried it for years because I find DosBox fits me much better for my Win 3.x needs. It is Win95 and 98 which gives me grief: (tried to insert an image, I can't as new user)
It gives me a protection error. "While initializing IOS Windows protection error. You need to restart your computer". Same error as if you use Qemu with KVM enabled. You can actually boot in safe mode, and thinking about it I had to start DOS to fdisk, format and start the installation... But win95 just won't start unless I deactivate acceleration or unless I do in safe mode. I have the same issue with Windows 98se: Protection error. You say you managed it, so maybe I need to pass some special parameters into the installer?
It gives me a protection error. "While initializing IOS Windows protection error. You need to restart your computer". Same error as if you use Qemu with KVM enabled. You can actually boot in safe mode, and thinking about it I had to start DOS to fdisk, format and start the installation... But win95 just won't start unless I deactivate acceleration or unless I do in safe mode. I have the same issue with Windows 98se: Protection error. You say you managed it, so maybe I need to pass some special parameters into the installer?
Last edited by mpack on 3. May 2020, 15:17, edited 2 times in total.
Reason: Remove verbatim quote of previous post.
Reason: Remove verbatim quote of previous post.
Re: Option to uncheck VT-x acceleration is ignored. W9x guest
Well, it was fixed! Thanks for the replies. I actually looked at the error after reading that you managed W98 and saw a guy which made a patch for the W95 kernel. Again, I can't post links, but the file is called FIX95CPU_V3_FINAL.ZIP. There is an iso inside and a floppy image. The think is not as much kvm, but the fact that windows95 dies when in a cpu over 1.3 ghz and win98 over 3ghz. I solved by mounting the floppy image and restarting the VM. Then an installer appeared and patched the kernel. Lucky because safe mode in 95 doesn't support a CD drive. I was able to finish installation and I have currently a box open with W95 with all the wonders of KVM and an overeating 100%CPU due to lack of interrupts.
That said, I already had a blue screen and some errors of libraries not found. I don't know how much it is due to the patch, or it is just standard W95 bullshitery, so mind it can be even more unstable.
Thanks for the tips!
That said, I already had a blue screen and some errors of libraries not found. I don't know how much it is due to the patch, or it is just standard W95 bullshitery, so mind it can be even more unstable.
Thanks for the tips!
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Re: [FIXED] Option to uncheck VT-x acceleration is ignored. W9x guest
On CPU usage. If I remember correctly there was a little program called Rain that you could install in Win95/Win98 to force the OS to halt the CPU when idle, instead of sitting in an energy wasting idle loop. Of course this will also reduce apparant CPU use.
Note however that there's a better solution for Win98SE, which is to install it with ACPI support per our own FAQ. That way it supports power (and cpu idle) management directly, and doesn't need third party hacks. This is the variant of Win98SE you would have installed on a laptop back in the day.
Note however that there's a better solution for Win98SE, which is to install it with ACPI support per our own FAQ. That way it supports power (and cpu idle) management directly, and doesn't need third party hacks. This is the variant of Win98SE you would have installed on a laptop back in the day.