running 16bit code

[David Laight]

Does wine support running of 16bit windows apps?
If so does it rely on the underlying OS having support
for 'virtual 8086 emulation'?

I'm thinking of removing the VM86 support from NetBSD,
and wine is about the only likley user.

David

[Damjan Jovanovic]

On Tue, May 8, 2012 at 11:40 AM, David Laight  wrote:
> Does wine support running of 16bit windows apps?
> If so does it rely on the underlying OS having support
> for 'virtual 8086 emulation'?
>
> I'm thinking of removing the VM86 support from NetBSD,
> and wine is about the only likley user.
>
> David
>
> --
> David Laight: [e-mail]

16 bit Windows applications are written and compiled to either use
real mode or 16 bit protected mode.
Those that use real mode (mostly MS-DOS and Windows 1 and 2
applications) need virtual 8086 mode.
Those that use protected mode (mostly Windows >= 3.0 applications)
don't need virtual 8086 mode.

You'd break DOSBOX a lot more than Wine. But why do you want to remove
this from NetBSD? I thought compatibility with other operating systems
was one of its major features?

Damjan

[David Laight]

On Tue, May 08, 2012 at 12:03:52PM +0200, Damjan Jovanovic wrote:
> On Tue, May 8, 2012 at 11:40 AM, David Laight  wrote:
> > Does wine support running of 16bit windows apps?
> > If so does it rely on the underlying OS having support
> > for 'virtual 8086 emulation'?
> >
> > I'm thinking of removing the VM86 support from NetBSD,
> > and wine is about the only likely user.
> >
> > ? ? ? ?David
> >
> > --
> > David Laight: [e-mail]
>
> 16 bit Windows applications are written and compiled to either use
> real mode or 16 bit protected mode.
> Those that use real mode (mostly MS-DOS and Windows 1 and 2
> applications) need virtual 8086 mode.
> Those that use protected mode (mostly Windows >= 3.0 applications)
> don't need virtual 8086 mode.

Ok, so wine users would be very unlikely to be affected.
Since most of the 16bit apps post-date windows 3.
> You'd break DOSBOX a lot more than Wine.

Possibly, although some emulators are probably better bets for DOS.
> But why do you want to remove
> this from NetBSD? I thought compatibility with other operating systems
> was one of its major features?

Mainly because it isn't used much, and may well contain security holes.
There are two separate kernel options VM86 (usually enabled) and
KVM86 (usually disabled).
Both change some low level code is obscure ways.

David

[Marcus Meissner]

On Tue, May 08, 2012 at 12:06:23PM +0100, David Laight wrote:
> On Tue, May 08, 2012 at 12:03:52PM +0200, Damjan Jovanovic wrote:
> > On Tue, May 8, 2012 at 11:40 AM, David Laight  wrote:
> > > Does wine support running of 16bit windows apps?
> > > If so does it rely on the underlying OS having support
> > > for 'virtual 8086 emulation'?
> > >
> > > I'm thinking of removing the VM86 support from NetBSD,
> > > and wine is about the only likely user.
> > >
> > > ? ? ? ?David
> > >
> > > --
> > > David Laight: [e-mail]
> >
> > 16 bit Windows applications are written and compiled to either use
> > real mode or 16 bit protected mode.
> > Those that use real mode (mostly MS-DOS and Windows 1 and 2
> > applications) need virtual 8086 mode.
> > Those that use protected mode (mostly Windows >= 3.0 applications)
> > don't need virtual 8086 mode.
>
> Ok, so wine users would be very unlikely to be affected.
> Since most of the 16bit apps post-date windows 3.

Correct.
> > You'd break DOSBOX a lot more than Wine.
>
> Possibly, although some emulators are probably better bets for DOS.
> > But why do you want to remove
> > this from NetBSD? I thought compatibility with other operating systems
> > was one of its major features?
>
> Mainly because it isn't used much, and may well contain security holes.
> There are two separate kernel options VM86 (usually enabled) and
> KVM86 (usually disabled).
> Both change some low level code is obscure ways.

for what it is worth...

DOSBOX and DOSEMU can fall back to full emulation today, so vm86 not
strictly required anymore these days. Speed is probably no longer an
issue ;)

Ciao, Marcus

[Stefan Dösinger]

Am Dienstag, 8. Mai 2012, 13:31:00 schrieb Marcus Meissner:
> DOSBOX and DOSEMU can fall back to full emulation today, so vm86 not
> strictly required anymore these days. Speed is probably no longer an
> issue ;)

No, speed is still an issue. DOSBOX is too slow to run Settlers 2 and Screamer 
2(aka Bleifuß 2) on my Core 2 Duo CPU. Dosemu works for Settlers 2(I estimate 
that it is about 20 times faster), and Screamer 2 works with some 3DFX hacks 
that move the graphics calculations into the GPU.

Ok, I realize that this is borderline off-topic, and both games aren't real 
mode apps strictly speaking, but 32 bit protected mode DOS/4G programs. They 
still need 16 bit real mode to launch though.

[Alexandre Julliard]

David Laight  writes:
> Does wine support running of 16bit windows apps?
> If so does it rely on the underlying OS having support
> for 'virtual 8086 emulation'?
>
> I'm thinking of removing the VM86 support from NetBSD,
> and wine is about the only likley user.

Wine is not going to use vm86 on NetBSD. In fact it will probably stop
using vm86 on Linux in the near future. Note that 16-bit Windows apps
don't need vm86, only DOS apps do.