seems I finally found what upset kqemu on amd64 SMP... shared gdt! (please test patch :)

[Bakul Shah]

On Wed, 07 May 2008 15:54:56 +1000 Bruce Evans <brde at optusnet.com.au>  wrote:
> On Tue, 6 May 2008, Bakul Shah wrote:
> 
> > On Tue, 06 May 2008 22:02:28 +0200 Teufel <bsd at kuehlbox.de>  wrote:
> >> Bakul Shah wrote:
> >>>> at needs to be done to fix that?
> >>>
> >>> Comment it out in amd64/amd64/trap.c!
> 
> Bletch.
> 
> >> getting rid of the message, yes.. but without further issues?
> >
> > The message is there "because you are not supposed to do it"
> 
> s/you/kqemu/ (or interpret what you are not supposed to do as "running kqemu"
> .
> 
> > See for instance
> >
> > http://docs.freebsd.org/cgi/getmsg.cgi?fetch=100953+0+archive/2007/freebsd-
> emulation/20070415.freebsd-emulation
> >
> > This seems to have not caused any problem in practice.  And
> > any way taking out the message doesn't change the essential
> > behavior (the invariant is still broken) but it can speed up
> > your emulation considerably.
> 
> I should have changed it to a panic long ago.  That would give the correct
> number of messages (1) :-).

Too late now for you to go fundamentalist :-)

> i386 still doesn't even print a message (perhaps it never did).  The
> bug would probably never have existed in any FreeBSD version of kqemu if
> i386 had had enough invariant checking.

It does (in isa/npx.c) and I've disabled it!

I seem to recall it is not just qemu but also some ndis
drivers that trigger this fpudna/npxdna message?  Didn't
someone (Attilio?) has ported dragonfly code to allow FPU
register use in kernel mode?  Whatever happened to it?