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List:       qemu-discuss
Subject:    Re: Windows 9x - which graphic?
From:       Narcis Garcia <narcisgarcia () gilug ! org>
Date:       2021-12-03 19:33:35
Message-ID: 6a938ee9-6dfc-9312-1843-3839d5e303a3 () gilug ! org
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Thanks.
Thank you for detailed report.


Narcis Garcia

El 3/12/21 a les 16:44, Maxim Levitsky ha escrit:
> On Mon, 2021-06-07 at 18:15 +0000, Philipp Ammann wrote:
> > Am 07.06.21 um 16:27 schrieb Simon Becherer:
> > > I tried minport vbe driver
> > > (https://web.archive.org/web/20191129030225/https://bearwindows.zcm.com.au/vbe9x.htm#2)
> > >  with cirrus/vga/vmga card
> > > and cirrus driver with cirrus card - but without sucess.
> > > Both 95 and 98 hangs during shutting down :(
> > > 
> > > Any hints?
> > 
> > Cirrus should work fine with the stock drivers included in Windows.
> > Personally I'm using vmware with the official VMware driver. You can
> > extract the driver for Win9x from preWin2k.iso shipped with VMware.
> > 
> > Bonus: set vmport=on (may be default) an install the vmmouse driver from
> > said ISO, and try vmxnet3 if you need networking.
> > 
> 
> I have a win98 VM with qemu/kvm and  I play with it once a while,
> because win98 was my first and last windows I used as a primary OS before
> I discovered and switched to Linux.
> 
> Many will disagree with me but I still think that win98 was the last windows \
> version that didn't suck at least from user perspective.
> Even despite the crashes/etc.
> 
> Here are few tips I know of running win98 on KVM/Qemu:
> 
> * Cirrus works (and it was my GPU back when I used win98 on real hardware),
> and is the most accurate, but is *slow* and very resolution limited.
> 
> (I can't understand how I could use 800x600 for so many years, and then I remember \
> I finally updated to 1024x768, that was awesome and then when I switched to \
> 1280x1024, it felt like I have infinite space. These days I use 41 inch 4K monitor \
> for my work, and I'll say it is about the amount of space I would like to have. 
> For the win98 VM I use a standard VGA and found a universal VGA driver for it.
> 
> I think I use the one from https://bearwindows.zcm.com.au/vbe9x.htm.
> 
> The downsides of VGA driver I think are that if you attempt to open DOS prompt,
> the screen fills with garbage, I think that DOS gets direct access to VGA registers \
> or something, and messes something up. It does work on cirrus though.
> 
> * That hang on shutdown I have seen too. Seems if you open a full screen DOS window \
> once, then it works (full screen window doesn't garbage the screen).
> I setup a dummy PIF file in the autostart folder that does that for me.
> It also smells like some bug in Qemu VGA implementaiton.
> 
> * KVM also used to make windows hang on boot when its logo is shown, but it got \
> fixed some kernels ago, so logo=0 in msdos.sys is no longer needed to boot it.
> 
> 
> * Mouse. If you use win98 SE, then you have support for USB, and qemu's tablet \
> works and works very well. You do need to manually install driver for PnP BIOS \
> though, but I guess you already did that. 
> 
> * Storage: I enabled DMA on IDE controller, seemed to be disabled by default, and \
> helped a lot with speed. 
> 
> * Sound: the SB16 works, but causes the mouse to freeze while sound playing. It is \
> also very inefficient, as it uses PIO.
> 
> I use AC97 driver for which I found very old win95 drivers which seems to work \
> (win98 drivers crash) It might be this driver: \
> https://archive.org/details/ac97-win95 
> 
> * Usage on any AMD processor (or at least Ryzen):
> 
> Sadly win98 contains a TLB flush bug, such as it doesn't flush TLB after it \
> modifies a page table entry, with invtlb.
> Ryzen's TLB is more speculative that Intel's and it just makes the guest show error \
> messages, all the time, and be mostly unusable, while in Intel's cpus for which it \
> was developed, it seems to "work" 
> What partially helps is to disable swap file in the guest but doesn't fully \
> eliminate it of course. 
> What is even funnier is that when you use KVM's shadow MMU (use kvm_amd kernel \
> module with npt=0), the bug is still present because well KVM's shadow MMU also \
> speculates. I do  have a patch which I use locally sometimes to make it strict and \
> then win98 works relatively fine. (I still see some crashes and hangs once in a \
> while, but they might be even because the OS itself isn't that stable). 
> To use the attached patch you need to add 'strict_mmu=1' option to the kvm module \
> (note, not kvm_amd), and load kvm_amd module with npt=0.
> Of course the sad part is that in this configuration you can't really run any other \
> VMs, as they are just too slow, so I have to reload kvm kernel modules when I like \
> to play with win98 VM. 
> Also on Ryzen 1, there was something related to VME extension, but I think that AMD \
> fixed it. 
> 
> No luck so far with VFIO. I have a very old nvidia card (7600GS I think) and once I \
> was able to pass it through to winxp VM on KVM, and recently I was able to make it \
> at least show something on screen with a eGPU box, but alas I think that the card \
> died. I don't think that this card supports win98 though. Since I still have that \
> eGPU box, I might as well one day buy an older card and try to pass it through.
> 
> 
> And last thing, something curious. Every time I see win98 desktop in a window, I \
> think that sides of the window are curved inside, like a kind of pincushion \
> distortion. The only explanation I can have is that my brain still applies \
> geometric correction to flatten the CRT image. OK, enough nostalgia from me!
> 
> Best regards,
> 	Maxim Levitsky
> 
> 
> 
> 


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