-----Original Message----- From: dri-devel [mailto:dri-devel-bounces@lists.freedesktop.org] On Behalf Of Daniel Vetter Sent: Thursday, August 04, 2016 1:23 PM To: Alex Deucher Cc: Deng, Emily; amd-gfx list; Maling list - DRI developers Subject: Re: [PATCH 00/13] drm/amdgpu: Add virtual display feature.
On Thu, Aug 04, 2016 at 12:53:04PM -0400, Alex Deucher wrote:
On Thu, Aug 4, 2016 at 12:24 PM, Daniel Vetter daniel@ffwll.ch wrote:
On Thu, Aug 04, 2016 at 10:59:38AM -0400, Alex Deucher wrote:
Adding dri-devel.
This patch set basically adds a driver option to enable virtual display hw if the user needs it (e.g., virtualization environments, headless cards, pre-silicon environments, etc.). It looks like a regular KMS crtc/encoder/connector and works with existing userspace unchanged.
We autodetect this already for virtualized envirnments and pre-silicon.
What do you mean? What do you do in those cases?
So virtualized (xengt) I think just fakes one display/connector, I didn't really check the details tbh. We had code floating around (but not merged) for the management console on servers, which injected a special config into iirc the VGA port. So a mix of kernel driver and hw/firmware tricks.
Pre-silicon just has a bunch of things to fake enough of a display since not all environments have the full display block simulated.
Anyway just wanted to say that we have piles of precendence for faking semi- virtual outputs.
Not so sure about headless cards, on those we don't bother to expose anything if there's nothing connected (i.e. no crtc/encoder/plane or connector objects at all). Why do you want fake outputs in that case?
We have some customers that want to run X or other desktops on hardware without display connectors or even chips without display hw at all.
Hm, for that I'd say virtual output/screen in X. Adding a fake output in the kernel where there really is nothing at all feels a bit wrong. All the examples above mean that the output is actually connected to something on the other side (screen on the management console, host OS for xengt or pre-silicon simulations).
Anyway, if this is just a modparam and disabled by default I don't see any issue really at all.
Yes, this is controlled by a module option and is intended to only be enabled by the user for specific use cases.
Another option for entirely fake outputs would be vkms.ko, similar to vgem.ko. With the simple display driver it should be fairly easy to a simple fake kms driver with just 1 crtc/encoder/connector/plane, all virtual, up&running. Needs a few lines to implement dumb mmap on top of shmem (but nothing else, since the driver never reads the buffer), plus prime import/export scaffolding. One module option (could even adjust at runtime) to configure how many drm_device instance there should be. Output configuration could be done by injecting a suitable EDID plus forcing the connector state (we have interfaces for that already, and iirc even patches to expose them all in sysfs).
I'd say if you really want entirely fake/virtual outputs that go exactly nowhere at all, vkms.ko would be the cleanest approach. And that would have lots of use-cases outputs of just what you need, for e.g. testing kms helpers/ioctls and other nice things.
FWIW I don't think we ever plan to have virtual outputs that go nowhere - the display content just might go out via VNC or a compressed streaming interface rather than through a local display controller.
-Daniel
Alex
-Daniel
Alex
On Thu, Aug 4, 2016 at 3:04 AM, Emily Deng Emily.Deng@amd.com
wrote:
The Virtual Display feature is to fake a display engine in amdgpu kernel
driver, which allows any other kernel modules or user mode components to work as expected even without real display HW. User can get the desktop/primary surface through remote desktop tools instead of displaying HW associated with the GPU.
The virtual display feature is designed for following cases: 1)Headless GPU, which has no display engine, while for some reason the X server is required to initialize in this GPU; 2)GPU with head (display engine) but Video BIOS disables display capability for
some reason. For example, SR-IOV virtualization enabled Video BIOS often disables display connector. Some S-series Pro-Graphics designed for headless computer also disable display capability in Video BIOS; 3)For whatever reason, end user wants to enable a virtual display (don’t need HW display capability).
Emily Deng (13): drm/amdgpu: Add virtual connector and encoder macros. drm/amdgpu: Initialize dce_virtual_ip_funcs drm/amdgpu: Initialize dce_virtual_display_funcs. drm/amdgpu: Initialize crtc, pageflip irq funcs drm/amdgpu: Initialize dce_virtual_crtc_helper_funcs drm/amdgpu: Initialize dce_virtual_crtc_funcs. drm/amdgpu: Disable VGA render and crtc when init GMC. drm/amdgpu: Use software timer to generate vsync interrupt. drm/amdgpu: Call pageflip irq funtion when receiced vsync interrupt. drm/amdgpu: Add DRM_MODE_CONNECTOR_VIRTUAL connector in amdgpu_connector_add. drm/amdgpu: Define vitual display ip blocks. drm/amdgpu: Define one variable for virtual display. drm/amdgpu: Set ip_blocks according variable
amdgpu_virtual_display.
drivers/gpu/drm/amd/amdgpu/Makefile | 3 +- drivers/gpu/drm/amd/amdgpu/ObjectID.h | 7 + drivers/gpu/drm/amd/amdgpu/amdgpu.h | 3 + drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c | 27 + drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.h | 2 + drivers/gpu/drm/amd/amdgpu/amdgpu_connectors.c | 95 +++ drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 5 + drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 5 +- drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 4 + drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h | 9 +- drivers/gpu/drm/amd/amdgpu/cik.c | 445 +++++++++++-- drivers/gpu/drm/amd/amdgpu/dce_v10_0.c | 75 +++ drivers/gpu/drm/amd/amdgpu/dce_v10_0.h | 2 + drivers/gpu/drm/amd/amdgpu/dce_v11_0.c | 83 +++ drivers/gpu/drm/amd/amdgpu/dce_v11_0.h | 2 + drivers/gpu/drm/amd/amdgpu/dce_v8_0.c | 82 +++ drivers/gpu/drm/amd/amdgpu/dce_v8_0.h | 2 + drivers/gpu/drm/amd/amdgpu/dce_virtual.c | 855
+++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/dce_virtual.h | 31 + drivers/gpu/drm/amd/amdgpu/vi.c | 416 ++++++++++-- 20 files changed, 2062 insertions(+), 91 deletions(-) create mode 100644 drivers/gpu/drm/amd/amdgpu/dce_virtual.c create mode 100644 drivers/gpu/drm/amd/amdgpu/dce_virtual.h
-- 1.9.1
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-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel