[PATCH 00/13] drm/amdgpu: Add virtual display feature.
Daniel Vetter
daniel at ffwll.ch
Thu Aug 4 17:23:19 UTC 2016
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 at 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.
-Daniel
>
> Alex
>
> > -Daniel
> >
> >>
> >> Alex
> >>
> >> On Thu, Aug 4, 2016 at 3:04 AM, Emily Deng <Emily.Deng at 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
> >> >
> >> > _______________________________________________
> >> > amd-gfx mailing list
> >> > amd-gfx at lists.freedesktop.org
> >> > https://lists.freedesktop.org/mailman/listinfo/amd-gfx
> >> _______________________________________________
> >> dri-devel mailing list
> >> dri-devel at lists.freedesktop.org
> >> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
More information about the dri-devel
mailing list