Removing vm86 support?

Josh Boyer jwboyer at
Wed Jul 8 13:02:43 UTC 2015

On Tue, Jul 7, 2015 at 7:20 PM, Andrew Lutomirski <luto at> wrote:
> Hi-
> I'm asking here because Fedora seems to one of few distros that
> enables CONFIG_VM86 on 32-bit kernels.

I'm somewhat confused as to how that is to be honest.  We don't
explicitly set it in our config hunks, and we disable CONFIG_EXPERT,
which is what the upstream option appears to require.  So I believe
the only reason it is enabled is because upstream has default y and
some weird Kconfig interaction isn't playing nice and allowing it to
be set even when CONFIG_EXPERT is not.

> Would anyone object if the upstream kernel (and hence Fedora) removed
> vm86 support?  This would break 16-bit real mode programs under
> dosemu.  It would have no effect on 16-bit protected mode programs
> under dosemu (i.e. anything that works on a 64-bit kernel), on dosbox
> (which you should be using instead of dosemu anyway) or on KVM (which
> is also a much better option than dosemu).

I don't think you're going to get anything resembling an authoritative
answer from this list.  Here are a few things that might be helpful to

1) The 32-bit x86 kernels are extremely low priority in general for
the kernel team.  To the point where we announced that they really
need extended community effort for truly 32-bit specific issues.

2) Fedora doesn't ship any code that would hit this that I'm aware of.
Certainly end users might have some, but our community tends to favor
"first and fast" over "historical code".

3) As a start, I'm more than happy to disable CONFIG_VM86 in rawhide
and see if people complain.


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