Re: [RFC PATCH v4] fw/pci: Add support for mapping Intel IGD via QEMU

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 23 Feb 2016 10:22:33 -0500
"Kevin O'Connor" <kevin@koconnor.net> wrote:

> On Tue, Feb 16, 2016 at 02:39:27PM -0700, Alex Williamson wrote:
> > QEMU provides two fw_cfg files to support IGD.  The first holds the
> > OpRegion data which holds the Video BIOS Table (VBT).  This needs to
> > be copied into reserved memory and the address stored in the ASL
> > Storage register of the device at 0xFC offset in PCI config space.
> > The OpRegion is generally 8KB.  This file is named "etc/igd-opregion".
> > 
> > The second file tells us the required size of the stolen memory space
> > for the device.  This is a dummy file, it has no backing so we only
> > allocate the space without copying anything into it.  This space
> > requires 1MB alignment and is generally either 1MB or 2MB, depending
> > on the hardware config.  If the user has opted in QEMU to expose
> > additional stolen memory beyond the GTT (GGMS), the GMS may add an
> > additional 32MB to 512MB.  The base address of the reserved memory
> > allocated for this is written back to the Base Data of Stolen Memory
> > register (BDSM) at PCI config offset 0x5C on the device.  This file is
> > named "etc/igd-bdsm".  
> 
> Thanks.  I'd be interested in seeing how the discussion with Michael
> and Igor works out (wrt using a standardized interface for
> communicating addresses between qemu and firmware) before adopting
> this interface in SeaBIOS.

Apologies if I missed it, but I haven't seen any work in this
direction, please point me to it if I'm wrong.  Now that QEMU 2.6 is
wrapping up, I'd like to get IGD assignment support in for 2.7, but we
can't do that without BIOS support.  How shall we proceed?  Thanks,

Alex