Re: [SeaBIOS] [RFC PATCH v3 0/3] Add segment limit checks to emulator

[Kevin O'Connor]

On Sun, Jul 25, 2010 at 09:34:38PM +0300, Avi Kivity wrote:
> On 07/25/2010 08:19 PM, Kevin O'Connor wrote:
> > Only the ljmpw is in big real mode with a code address>64K - the
> > "Disable protected mode" code is technically in 16bit protected mode.
> > I'm not sure if that helps explain why it works.
>
> What happens is kvm enters real  mode with cs.limit=0xffff, the
> guest #GPs due to segment limit violation, and enters the emulator,
> which emulates the far jump correctly.
>
> So this works, and will continue to work even after we fix limit
> checking.  It's still cleaner IMO to use normal code segments.

Makes sense.  I committed the patch that avoids this behavior to
SeaBIOS git.

-Kevin