I'd have to agree here--for the most part. A good example of this is how
old DOS programs did curses-style GUI in DOS-MODE (no windows yet--XTREEPRO
for instance I think does this). Many people here know about the IAPx
screen character buffer. This is MMIO by most definitions--although it
isn't handled directly (the IO part is done by hardware), but it is still IO
that plex86 needs to catch and redirect.
Drew Northup, N1XIM
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf
> Of Ulrich Weigand
> Sent: Saturday, December 16, 2000 10:54 AM
> To: [EMAIL PROTECTED]
> Subject: Re: [plex86] Performance enhancement: elminiating mode and
> context
>
>
>
> Ramon van Handel wrote:
>
> > On Fri, 15 Dec 2000, Kevin Lawton wrote:
> > > Running guest ring0 code at ring0 open memory access to
> PTE.P==1 pages,
> > > which includes the monitor interrupt handlers, and monitor data
> > > structures. Thus, all memory access instructions would be dangerous.
> > > We'd have to move to the concept of 'shortening' guest kernel
> segments,
> > > so we leave our selves a safe hole to put the monitor in.
> >
> > You need to prescan memory accesses anyway in order to catch MMIO.
>
> Eh? Whether a memory access is MMIO or not depends not on the
> instruction stream, but on the *address* that is used. You cannot
> know from just looking at the instructions (which is what prescanning
> does), what values the registers used for address generation will have
> when the code is executed ...
>
> The only way to catch memory accesses without hardware assistance
> is full emulation, which I don't think you want to advocate ;-)
>
> Bye,
> Ulrich
>
> --
> Dr. Ulrich Weigand
> [EMAIL PROTECTED]
>
