Re: [Qemu-devel] [SeaBIOS] [RFC PATCH 0/2] Allow RedHat PCI bridges reserve more buses than necessary during init

[Marcel Apfelbaum]

On 21/07/2017 15:42, Gerd Hoffmann wrote:
> On Fri, 2017-07-21 at 15:15 +0300, Marcel Apfelbaum wrote:
> > On 21/07/2017 13:04, Gerd Hoffmann wrote:
> > >     Hi,
> > >
> > > > > What about window sizes?  IIRC there was a plan to provide
> > > > > allocation
> > > > > hints for them too ...
> > > >
> > > > Yes, is in my TODO list, however not as part of Aleksandr's
> > > > series
> > > > which aims to provide PCIe-PCI bridge hotplug support.
> > >
> > > I'd prefer to have a single vendor capability for all resource
> > > allocation hints provided by qemu.
> >
> > [Adding Laszlo]
> >
> >
> > Sure, the capability looking something like:
> >
> >      [flags: reserve-buses|reserve-IO|reserve-MEM|...]
> >      [extra-buses][IO-size][MEM-size]
> >
> >      if reserve-buses -> use 'extra-buses' value and so on
>
> Do we need the flags?  We can use "value == 0 -> no hint for you".

Maybe we don't want to allocate IO at all,
So value 0 would say do not allocate.

But we can disable IO by other means.

> Also what about prefetchable vs. non-prefetchable memory?  I guess we
> want a size hint for both memory windows?


Good point, thanks!
Marcel

> cheers,
>    Gerd