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Mon, 31 Jul 2023 18:17:44 -0700 (PDT) Received: from gurchetansingh0.mtv.corp.google.com ([2620:15c:a7:2:cb47:8a0d:6476:3e7b]) by smtp.gmail.com with ESMTPSA id v20-20020a17090a899400b00260a5ecd273sm6657722pjn.1.2023.07.31.18.17.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 Jul 2023 18:17:43 -0700 (PDT) From: Gurchetan Singh To: qemu-devel@nongnu.org Cc: kraxel@redhat.com, marcandre.lureau@redhat.com, akihiko.odaki@gmail.com, dmitry.osipenko@collabora.com, ray.huang@amd.com, alex.bennee@linaro.org, shentey@gmail.com, hi@alyssa.is Subject: [PATCH v2 9/9] docs/system: add basic virtio-gpu documentation Date: Mon, 31 Jul 2023 18:17:23 -0700 Message-Id: <20230801011723.627-10-gurchetansingh@chromium.org> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20230801011723.627-1-gurchetansingh@chromium.org> References: <20230801011723.627-1-gurchetansingh@chromium.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::329; envelope-from=gurchetansingh@chromium.org; helo=mail-ot1-x329.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, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org 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. +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 +MMIO. For PCI, you can suffix it with -pci. Without these suffixes, the +platform default will be chosen. The syntax of available combinations +is listed below. + + * ``virtio-vga[-BACKEND]`` + * ``virtio-gpu[-BACKEND][-INTERFACE]`` + * ``vhost-user-vga`` + * ``vhost-user-pci`` + +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 +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. + +The crosvm book provides directions on how to build a `gfxstream-enabled +rutabaga`_ and launch a `guest Wayland compositor`_. + +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