Hi,
I consider adding EDID support to qemu, for display configuration.
qemu patches are here:
https://git.kraxel.org/cgit/qemu/log/?h=sirius/edid
linux kernel patches are here:
https://git.kraxel.org/cgit/linux/log/?h=edid
Current (experimental) patches have support for the stdvga and
virtio-vga.
I think it would be quite useful for vgpu too. Unlike emulated devices
vgpu's do not have a paravirtual display configuration path, because the
standard way to configure the display is to simply read the edid from
the monitor.
Intel has two hard-coded edid blobs for that (depending on vgpu type).
Not sure how nvidia handles this, but probably simliar. With qemu
passing a edid blob for the virtual display instead of using the
hardcoded blob we could make the display configuration much more
flexible.
Ideally qemu would also be able to update the edid blob at any time, and
the vgpu will notify the guest about it (probably by emulating a monitor
hotplug event). The guest can react on qemu window resizing then and
adapt automatically, simliar to how it works with qxl and virtio-gpu.
The guest and the vgpu should be able to handle "odd" non-standard
display resolutions like this (coming from random window resizing):
Detailed mode: Clock 106.620 MHz, 477 mm x 330 mm
1212 1515 1551 1636 hborder 0
840 844 848 869 vborder 0
-hsync -vsync
VertFreq: 74 Hz, HorFreq: 65171 Hz
RfC patch for the vfio interface is below.
Comments?
cheers,
Gerd
=================== cut here ===================
>From 556299e8c6280b1c4061fdae15491a013c22be98 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Date: Thu, 6 Sep 2018 16:17:17 +0200
Subject: [PATCH] [RfC] vfio: edid interface
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
include/uapi/linux/vfio.h | 42 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 1aa7b82e81..9ac7dfb7c1 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -602,6 +602,48 @@ struct vfio_device_ioeventfd {
#define VFIO_DEVICE_IOEVENTFD _IO(VFIO_TYPE, VFIO_BASE + 16)
+/**
+ * VFIO_DEVICE_GFX_EDID_CAPS - _IOW(VFIO_TYPE, VFIO_BASE + 17,
+ * struct vfio_device_gfx_edid_caps)
+ *
+ * Get edid capabilities.
+ *
+ * Drivers must support either none or both GFX_EDID ioctls,
+ * so the CAPS ioctl can also be used to probe for edid support.
+ *
+ * max_xres, max_yres - maximum display resolution supported.
+ * value "0" means no restriction.
+ *
+ */
+struct vfio_device_gfx_edid_caps {
+ __u32 argsz;
+ __u32 flags;
+ /* out */
+ __u32 max_xres;
+ __u32 max_yres;
+};
+
+#define VFIO_DEVICE_GFX_EDID_CAPS _IO(VFIO_TYPE, VFIO_BASE + 17)
+
+/**
+ * VFIO_DEVICE_GFX_EDID_SET - _IOW(VFIO_TYPE, VFIO_BASE + 18,
+ * struct vfio_device_gfx_edid_set)
+ *
+ * Set edid blob.
+ *
+ * Should trigger monitor hotplug emulation, to notifiy the guest os
+ * that the edid has changed.
+ *
+ */
+struct vfio_device_gfx_edid_set {
+ __u32 argsz;
+ __u32 flags;
+ /* in */
+ __u8 edid[256];
+};
+
+#define VFIO_DEVICE_GFX_EDID_SET _IO(VFIO_TYPE, VFIO_BASE + 18)
+
/* -------- API for Type1 VFIO IOMMU -------- */
/**
--
2.9.3
