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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 03 Feb 2016 10:29:28 +0100
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Subject: Re: [Qemu-devel] [RFC PATCH v2 7/7] vfio/pci: Find and expose Intel
	IGD OpRegion
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To: Alex Williamson <alex.williamson@redhat.com>
Cc: qemu-devel@nongnu.org

On Di, 2016-02-02 at 13:09 -0700, Alex Williamson wrote:
> This is provided via a device specific region, look for it on Intel
> VGA class devices.  Our default mechanism to expose this to the BIOS
> is via fw_cfg where it's expected that the BIOS will copy the data
> into a reserved RAM area and update the ASL Storage register to
> reference the GPA of that buffer.

>   We also support directly mapping
> the OpRegion through to the host in response to the ASL Storage
> register write, which makes the data "live" and potentially provides
> write access should the underlying vfio region support writes.

This should better be splitted into a separate patch.

> This
> option is automatically enabled if we somehow don't support fw_cfg (is
> this a good idea?).

I think this can't happen.  And even in case it can: we have bigger
problems than the opregion then.

cheers,
  Gerd