Re: [PATCH v2] x86/vm86: Remove deprecated VM86 support

[Brian Gerst]

On Fri, May 29, 2026 at 1:21 AM Jari Ruusu <jariruusu@xxxxxxxxxxxxxx> wrote:
>
> Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> > I'm really curious what software this is and what kind
> > of performance boost you see.
>
> I am more or less "stuck" with old DOS version of WordPerfect
> for opening/editing/saving/printing some really old long-term
> industrial project documentations that were originally created
> more than 30 years ago. All attempts to open such files with
> other tools will always result in complete mess. Choices are:
> (1) re-do all those old project documentations with some other
> tool, or (2) start old DOS version of WordPerfect.
>
> With CONFIG_X86_LEGACY_VM86=y set in 32-bit Linux kernel,
> currently running linux-6.12.91, one memory+CPU intensive
> operation in DOS version of WordPerfect takes less than 0.5
> seconds. With CONFIG_X86_LEGACY_VM86 not set, same operation
> takes about 2 seconds.
>
> > I'm also curious why modern virtualization hardware
> > doesn't help either.
>
> My current setup uses virtualization:
>
> 64-bit x86 host + 64-bit Linux kernel/distro + Qemu/KVM
>   --> boots 32-bit Linux kernel/distro ( X86_LEGACY_VM86=y )
>     --> boots dosemu + FreeDOS
>       --> runs DOS version of WordPerfect

Can you run FreeDOS on Qemu/KVM directly, without the 32-bit Linux
guest in between?