Re: [PATCH v2] x86/vm86: Remove deprecated VM86 support
From: Jari Ruusu
Date: Thu May 28 2026 - 03:53:33 EST
Ashwin Gundarapu <linuxuser509@xxxxxxxxxxx> wrote:
> VM86 support allows 16-bit DOS programs to run in virtual 8086 mode
> on 32-bit x86 kernels. This feature has been deprecated and the Kconfig
> help text itself states that any recent software works without it.
>
> Remove the vm86 subsystem entirely including the main driver source,
> Kconfig options, header file, and all references in thread_info,
> processor, and processor-flags headers.
[SNIP]
> -config X86_LEGACY_VM86
> - bool "Legacy VM86 support"
> - depends on X86_32
> - help
> - This option allows user programs to put the CPU into V8086
> - mode, which is an 80286-era approximation of 16-bit real mode.
> -
> - Some very old versions of X and/or vbetool require this option
> - for user mode setting. Similarly, DOSEMU will use it if
> - available to accelerate real mode DOS programs. However, any
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> - recent version of DOSEMU, X, or vbetool should be fully
> - functional even without kernel VM86 support, as they will all
> - fall back to software emulation. Nevertheless, if you are using
> - a 16-bit DOS program where 16-bit performance matters, vm86
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> - mode might be faster than emulation and you might want to
> - enable this option.
There are still people using this who need that performance boost.
I am one of those weird ones who still occasionally run real mode
DOS programs under 32-bit x86 Linux + dosemu + FreeDOS.
I understand that my vote here does not count at all, but my vote is
still to keep X86_LEGACY_VM86 as it is, at least until year-2038
32-bit x86 time_t apocalypse kicks in, or X86_LEGACY_VM86 turns out
to be a security disaster or unreasonable maintenance burden.
--
Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189