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([2400:4050:a840:1e00:78d2:b862:10a7:d486]) by smtp.gmail.com with ESMTPSA id w5-20020a1709029a8500b001b03cda6389sm11545338plp.10.2023.08.01.23.37.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 01 Aug 2023 23:38:01 -0700 (PDT) Message-ID: <90b57a8f-e117-b95e-66c1-41c6c93a91f9@gmail.com> Date: Wed, 2 Aug 2023 15:37:58 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 9/9] docs/system: add basic virtio-gpu documentation Content-Language: en-US To: Gurchetan Singh , qemu-devel@nongnu.org Cc: kraxel@redhat.com, marcandre.lureau@redhat.com, dmitry.osipenko@collabora.com, ray.huang@amd.com, alex.bennee@linaro.org, shentey@gmail.com, hi@alyssa.is References: <20230801011723.627-1-gurchetansingh@chromium.org> <20230801011723.627-10-gurchetansingh@chromium.org> From: Akihiko Odaki In-Reply-To: <20230801011723.627-10-gurchetansingh@chromium.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::62e; envelope-from=akihiko.odaki@gmail.com; helo=mail-pl1-x62e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2023/08/01 10:17, Gurchetan Singh wrote: > This adds basic documentation for virtio-gpu. > > Suggested-by: Akihiko Odaki > Signed-off-by: Gurchetan Singh > > --- > v2: - Incorporated suggestions by Akihiko Odaki > - Listed the currently supported capset_names (Bernard) > > docs/system/device-emulation.rst | 1 + > docs/system/devices/virtio-gpu.rst | 98 ++++++++++++++++++++++++++++++ > 2 files changed, 99 insertions(+) > create mode 100644 docs/system/devices/virtio-gpu.rst > > diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst > index 4491c4cbf7..1167f3a9f2 100644 > --- a/docs/system/device-emulation.rst > +++ b/docs/system/device-emulation.rst > @@ -91,6 +91,7 @@ Emulated Devices > devices/nvme.rst > devices/usb.rst > devices/vhost-user.rst > + devices/virtio-gpu.rst > devices/virtio-pmem.rst > devices/vhost-user-rng.rst > devices/canokey.rst > diff --git a/docs/system/devices/virtio-gpu.rst b/docs/system/devices/virtio-gpu.rst > new file mode 100644 > index 0000000000..f359584033 > --- /dev/null > +++ b/docs/system/devices/virtio-gpu.rst > @@ -0,0 +1,98 @@ > +.. > + SPDX-License-Identifier: GPL-2.0 > + > +virtio-gpu > +========== > + > +This document explains the setup and usage of the virtio-gpu device. > +The virtio-gpu device paravirtualizes the GPU and display controller. > + > +Linux kernel support > +-------------------- > + > +virtio-gpu requires a guest Linux kernel built with the > +``CONFIG_DRM_VIRTIO_GPU`` option. > + > +QEMU virtio-gpu variants > +------------------------ > + > +QEMU provides a 2D virtio-gpu backend, and two accelerated backends: > +virglrenderer ('gl' device label) and rutabaga_gfx ('rutabaga' device > +label). There is a vhost-user backend that runs the graphics stack in > +a separate process for improved isolation. > + > +Theses backends can be further classified into VGA and non-VGA variants. It's a bit unsound wording. virglrenderer and rutabaga_gfx are certainly backends, but "VGA" is not; it describes an interface exposed to the guest > +The VGA ones are prefixed with virtio-vga or vhost-user-vga while the > +non-VGA ones are prefixed with virtio-gpu or vhost-user-gpu. > + > +The VGA ones always use PCI interface, but for the non-VGA ones, you can > +further pick simple MMIO or PCI. For MMIO, you can suffix the device > +name with -device though vhost-user-gpu apparently does not support You don't need the word "apparently" in the documentation. > +MMIO. For PCI, you can suffix it with -pci. Without these suffixes, the > +platform default will be chosen. The syntax of available combinations Duplicate whitespaces between "of" and "available". > +is listed below. > + > + * ``virtio-vga[-BACKEND]`` > + * ``virtio-gpu[-BACKEND][-INTERFACE]`` > + * ``vhost-user-vga`` > + * ``vhost-user-pci`` Probably this list should come first. > + > +This document uses the PCI variant in examples. > + > +virtio-gpu 2d > +------------- > + > +The default 2D backend only performs 2D operations. The guest needs to > +employ a software renderer for 3D graphics. > + > +Typically, the software renderer is provided by `Mesa`_ or `SwiftShader`_. > +Mesa's implementations (LLVMpipe, Lavapipe and virgl below) work out of box > +on typical modern Linux distributions. > + > +.. parsed-literal:: > + -device virtio-gpu-pci > + > +.. _Mesa: https://www.mesa3d.org/ > +.. _SwiftShader: https://github.com/google/swiftshader > + > +virtio-gpu virglrenderer > +------------------------ > + > +When using virgl accelerated graphics mode, OpenGL API calls are translated > +into an intermediate representation (see `Gallium3D`_). The intermediate Add "on the guest" to the first sentence for clarification. > +representation is communicated to the host and the `virglrenderer`_ library > +on the host translates the intermediate representation back to OpenGL API > +calls. > + > +.. parsed-literal:: > + -device virtio-gpu-gl-pci > + > +.. _Gallium3D: https://www.freedesktop.org/wiki/Software/gallium/ > +.. _virglrenderer: https://gitlab.freedesktop.org/virgl/virglrenderer/ > + > +virtio-gpu rutabaga > +------------------- > + > +virtio-gpu can also leverage `rutabaga_gfx`_ to provide `gfxstream`_ rendering > +and `Wayland display passthrough`_. With the gfxstream rendering mode, GLES > +and Vulkan calls are forwarded directly to the host with minimal modification. Nitpick: remove "directly". We already say "with minimal modification". > + > +The crosvm book provides directions on how to build a `gfxstream-enabled > +rutabaga`_ and launch a `guest Wayland compositor`_. It should be clarified it's not a conventional compositor but it's a proxy. > + > +This device does require host blob support (``hostmem`` field below), but not > +all capsets (``capset_names`` below) have to enabled when starting the device. > + > +The currently supported ``capset_names`` are ``gfxstream-vulkan`` and > +``cross-domain`` on Linux guests. For Android guests, ``gfxstream-gles`` is > +also supported. > + > +.. parsed-literal:: > + -device virtio-gpu-rutabaga-pci,capset_names=gfxstream-vulkan:cross-domain,\\ > + hostmem=8G,wayland_socket_path="$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY" > + > +.. _rutabaga_gfx: https://github.com/google/crosvm/blob/main/rutabaga_gfx/ffi/src/include/rutabaga_gfx_ffi.h > +.. _gfxstream: https://android.googlesource.com/platform/hardware/google/gfxstream/ > +.. _Wayland display passthrough: https://www.youtube.com/watch?v=OZJiHMtIQ2M > +.. _gfxstream-enabled rutabaga: https://crosvm.dev/book/appendix/rutabaga_gfx.html > +.. _guest Wayland compositor: https://crosvm.dev/book/devices/wayland.html