Re: [PATCH] x86/kconfig/32: Mark CONFIG_VM86 as BROKEN

From: Linus Torvalds
Date: Wed Jul 08 2015 - 13:55:34 EST


On Wed, Jul 8, 2015 at 10:49 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> I don't know how to tell whether something is trying to use real mode,
> but I can play this just fine in DOSEMU on my 64-bit laptop:

So a 64-bit distro obviously will never have used vm86 mode - it
doesn't work there. Never has. There's no sane way to get to vm86 mode
from long mode, that's just how the 64-bit extensions worked.

(64-bit hardware obviously does support vm86 mode, but you have to
play games with mixing long mode and CPL0 32-bit protected mode to get
there, and we never did that).

It's the 32-bit distros I would worry about. The ones that may have
well disabled emulation, because they have vm86 mode enabled.

Linus
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