Re: [Qemu-devel] Re: Suggestion - trap window-close of VM

[Ryan Rempel <rgrempel@gmail.com>]

On Tue, 29 Mar 2005 23:52:19 +0100, Paul Brook <paul@codesourcery.com> wrote:
> > This isn't working quite right for me with a Windows 98 guest -- it
> > traps the attempt to close the window all right, but it doesn't let
> > the window close even when Window 98 has in fact shut down.
> 
> As far as qemu is concerned there's nothing special about windows being "shut
> down". ie. it's not possible to tell if windows is doing something useful, or
> just sitting there waiting for you to turn it off.

Just to clarify, I was commenting on Struan's patch, which does try to
determine whether windows is "shut down" -- his patch seems to work
with a Windows 2000 guest, but not a Windows 98 guest (he reported the
former, I was reporting the latter).
 
> > I wonder
> > whether this is related to the "Windows 98 doesn't use the HLT
> > instruction" problem that is noted elsewhere (since that apparently
> > doesn't affect Windows 2000).
> 
> No. the HLT thing is just windows 9x being crap. It also happens on real
> hardware.
> 
> In theory windows should be able to "turn off" qemu using APM, like it does on
> real machines. However there seem to be bugs in the qemu implementation that
> stop this working.

Again to clarify, qemu does ordinarily quit as expected when I shut
down a Windows 98 guest -- I was commenting specifically on Struan's
patch, rather than qemu's normal behaviour. I was speculating that the
HLT instruction might have an impact on Struan's method to detect
whether windows had shut down (since it was a known difference between
Windows 98 and 2000), but I may well be barking up the wrong tree
there.