[Qemu-devel] Re: [PATCH] QEMU - provide e820 reserve through qemu_cfg

[Anthony Liguori]

On 01/25/2010 02:04 PM, Alexander Graf wrote:
> On 25.01.2010, at 18:46, Jes Sorensen wrote:
>
>    
> > On 01/25/10 18:28, Alexander Graf wrote:
> >      
> > > > > That way we'd get 2 entries and the chance to enhance them later on.
> > > > > In fact, it might even make sense to pass the whole table in such a
> > > > > form. That way qemu generates all of the e820 tables and we can
> > > > > declare whatever we want. Just add a type field in the table.
> > > > >            
> > > > I am fine with having QEMU build the e820 tables completely if there is
> > > > a consensus to take that path.
> > > >          
> > > I agree. We better get this right :-). I don't want to maintain 5
> > > versions of an 380 fw_cfg interface.
> > >        
> > Looking at the internals, some of the e820 entries are based on compile
> > time constants for the BIOS, so it will be hard to pass those from
> > QEMU, but we could do it in a way so we pass a number of additional
> > e820 entries. Ie. address, length, and type.
> >      
> Yes, sounds good. Should be fairly extensible then. What about memory holes? Do 
> we need to take care of them?
>    

It would be nice for QEMU to be able to add additional e820 regions that 
don't necessarily fit the standard layout model.

For instance, I've thought a number of times about using a large 
reserved region as a shared memory mechanism.

But we certainly need to allow the BIOS to define the regions it needs 
to know about.

Regards,

Anthony Liguori