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

[Dave Hansen]

On 5/28/26 22:20, Jari Ruusu wrote:
> 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.

Just out of curiosity, what operation is that? How often do you do that
operation in a day or a month?

>> 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

Just like Brian asked, I'm confused why this needs the 32-bit Linux
distro in the mix.

But, if I were you, I'd just keep the 32-bit distro image around, off
the Internet, and never update it. Just like the version of DOS you have
and WordPerfect. The 32-bit distro doesn't need a mainline kernel. It
just gets frozen in place with a 2026 kernel, just like your 1994
version of WordPerfect and DOS are frozen.

As I'm sure you know, that 32-bit distro is getting harder and harder to
keep updated. I've jumped around distros for 32-bit testing a few times
in the last decade as folks retired their 32-bit x86 ports. With Debian
gone, I'd expect its derivatives to die off in the next few years,
making this whole thing even harder.