Re: [Qemu-devel] [PATCH] hw/pci: completed master-abort emulation

[Michael S. Tsirkin]

corrected Anthony's mail.

On Tue, Sep 24, 2013 at 11:44:57AM +0300, Marcel Apfelbaum wrote:
> > Not necessarily. Another bridge can claim it then
> > terminate with MA.
> > 
> > Example:
> > 
> > -[0000:00]-+-00.0
> >            +-02.0
> >            +-16.0
> >            +-16.3
> >            +-19.0
> >            +-1a.0
> >            +-1b.0
> >            +-1c.0-[02]--
> >            +-1c.1-[03]----00.0
> >            +-1c.3-[05-0c]--
> >            +-1c.4-[0d]--+-00.0
> >            |            \-00.3
> > 
> > 
> > 
> > Device 03:00.0 writes to within memory window of 00:1c.4,
> > but outside BARs of both 0d:00.0 and 0d:00.3.
> > 
> > On PCI, I think MA is set in sec status register of 00:1c.4.
> You are right, my code will work only under the assumption
> that the devices do not communicate between them.
> I will state the above in the next version.
> 
> Thanks,
> Marcel

How hard is it to fix properly?
If that's hard, would it be easier to implement express
semantics unconditionally?