Re: [Qemu-devel] [PATCH 0/2 v2] pc: inform SeaBIOS where 64-bit PCI hole begins

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 29, 2013 at 04:28:25PM +0100, Igor Mammedov wrote:
> On Tue, 29 Oct 2013 17:10:47 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Tue, Oct 29, 2013 at 01:57:33PM +0100, Igor Mammedov wrote:
> > > * simplify PCI address space mapping into system address space,
> > >   replacing code duplication in piix/q53 PCs with a helper function
> > > 
> > > * add fw_cfg 'etc/pcimem64-minimum-address' to allow QEMU reserve
> > >   additional address space before 64-bit PCI hole. Which will be
> > >   need for reserving memory hotplug region in highmem.
> > >   SeaBIOS counterpart: http://patchwork.ozlabs.org/patch/283623/
> > 
> > I'd like to see if we can figure out the migration issue with
> > memory layout.
> It seems that there isn't migration issue here.

Hmm earlier you thought there was - it's ok now?

> > Because if we do, and get rid of the separate 64 bit
> > region as a concept, exposing the start of this non-existent
> > region in FW CFG will make very little sense IMHO.
> Well, BIOS have to know where it could start 64-bit BARs mappings
> and
> telling it explicitly where, looks like a good way to do it.

As far as I can tell, BIOS can start any mappings anywhere it wants to
as long as they don't overlap anything else.
What is has to know is what hardware is there.


> > 
> > > v2:
> > >  *  use negative priority to map PCI address space under RAM memory
> > >     regions which allows simplify code by removing pci_hole &
> > >     pci_hole64 memory region aliases
> > > 
> > > Series depends on:
> > >  "memory: Change MemoryRegion priorities from unsigned to signed:
> > > 
> > > Git tree for testing:
> > >   https://github.com/imammedo/qemu/commits/pcimem64-minimum-address-v2
> > > 
> > > Igor Mammedov (1):
> > >   pc: add 'etc/pcimem64-minimum-address' fw_cfg interface to SeaBIOS
> > > 
> > > Michael S. Tsirkin (1):
> > >   pc: map PCI address space as catchall region for not mapped addresses
> > > 
> > >  hw/i386/pc.c              |   28 ++++++++++++++++------------
> > >  hw/i386/pc_piix.c         |    2 --
> > >  hw/pci-host/piix.c        |   27 +++++----------------------
> > >  hw/pci-host/q35.c         |   28 ++++++----------------------
> > >  include/hw/i386/pc.h      |   15 +++------------
> > >  include/hw/pci-host/q35.h |    2 --
> > >  6 files changed, 30 insertions(+), 72 deletions(-)