Add README.md

README.md

+# QUICK HACK: Virtme for kernel developers
+
+Our first [blog post about virtme](https://www.collabora.com/news-and-blog/blog/2018/09/18/virtme-the-kernel-developers-best-friend/ ) showed how to use virtme for kernel development in general.
+
+Virtme is very convenient for testing the kernel inside a virtual machine (QEMU) without the need to install and maintain a full distro other then your host machine.
+
+In this post, we'll show you some quick hacks to use virtme in some specific usecases for your tests.
+
+# Qemu options - avoid "Out of memory" error
+
+Virtme doesn't select memory or number of CPUs to be used by QEMU, which sometimes causes out of memory error on boot.
+
+Lets use a variable to pass this resources to Virtme.
+Feel free to adjust the number of ram and cpu cores to be used.
+
+```
+export MEM_CPU="-m 2G -smp 2"
+```
+
+# Running Weston on virtme
+
+## Install weston in your host machine
+
+```
+sudo apt install weston
+```
+
+## Launch virtme
+
+This following command will launch virtme with a display, keeping the serial in the current console for convenience.
+
+```
+# NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
+$(host) virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+```
+
+Where $KDIR is the path of your kernel directory.
+
+## Launch weston
+
+```
+$(virtme) export XDG_RUNTIME_DIR=/tmp/${UID}-runtime-dir
+$(virtme) mkdir -p "${XDG_RUNTIME_DIR}"
+$(virtme) chmod 0700 "${XDG_RUNTIME_DIR}"
+$(virtme) weston --tty 1
+```
+
+[ image https://people.collabora.com/~koike/weston-virtme.png ]
+
+# Running vimc + libcamera on virtme
+
+To use vimc, remember to enable `CONFIG_VIDEO_VIMC=y` in kernel config.
+
+## Install libcamera and its dependencies
+
+```
+$(host) git clone git://linuxtv.org/libcamera.git
+$(host) cd libcamera
+
+# Check README.rst for updated dependency list and install instructions
+$(host) sudo apt install libgnutls28-dev openssl qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5
+
+$(host) meson build
+$(host) ninja -C build install
+```
+
+## Launch virtme + cam
+
+To run `cam` for capturing frames by command line, we don't need a display:
+
+```
+$(host) virtme-run --rwdir /tmp --kdir $KDIR --qemu-opts $MEM_CPU
+```
+
+Option `--rwdir /tmp` allows to read and write from the `/tmp/` folder in the host machine, so we can store the captured frames.
+
+```
+$(virtme) /usr/local/bin/cam -c 1 -C --file="/tmp/libcamframe#.data" -s width=1920,height=1080
+```
+
+To view the image in your host machine:
+
+```
+$(host) ffplay  -f rawvideo -pixel_format rgb24 -video_size "1920x1080" /tmp/libcamframestream0-000005.data
+```
+
+## Launch virtme + qcam
+
+To ran `qcam` you need to launch virtme with a display:
+
+```
+# NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
+$(host) virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+```
+
+Note: Nor weston or any other compositor need to be launched before qcam.
+
+```
+$(virtme) QT_QPA_PLATFORM=linuxfb /usr/local/bin/qcam -s width=1920,height=1080
+```
+
+// TODO: I had to make this change to make qcam work http://ix.io/2jqZ , since the pipeline advertises BGR24, but vimc doesn't support it.
+
+[image https://people.collabora.com/~koike/qcam-vimc.png ]
+
+
+# Running IGT graphics tests on virtme
+
+## Install IGT tests and its dependencies
+
+```
+$(host) git clone https://gitlab.freedesktop.org/drm/igt-gpu-tools.git
+$(host) cd igt-gpu-tools
+
+# Check README.rst for updated dependency list and install instructions
+
+$(host) sudo apt-get install \
+                        piglit \
+                        gcc \
+                        flex \
+                        bison \
+                        pkg-config \
+                        libatomic1 \
+                        libpciaccess-dev \
+                        libkmod-dev \
+                        libprocps-dev \
+                        libdw-dev \
+                        zlib1g-dev \
+                        liblzma-dev \
+                        libcairo-dev \
+                        libpixman-1-dev \
+                        libudev-dev \
+                        libxrandr-dev \
+                        libxv-dev \
+                        x11proto-dri2-dev \
+                        meson \
+                        libdrm-dev^C
+
+$(host) meson -Drunner=enabled build
+$(host) ninja -C build
+```
+
+## Running IGT on virtio-gpu
+
+Start virtme:
+
+```
+# NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
+$(host) virtme-run --rwdir /tmp --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+```
+
+And run the tests:
+
+```
+$(virtme) cd path/to/igt-gpu-tools
+
+# Running specific test
+$(virtme) ./build/tests/kms_flip --run-subtest wf_vblank-ts-check
+
+# Or running a set of tests, and generating html summary
+$(virtme) ./scripts/run-tests.sh -s -t "kms_*" -r /tmp/results
+$(host) see /tmp/results/html/index.html
+```
+
+[image https://people.collabora.com/~koike/igt-qemu.png ]
+
+## Running IGT on vKMS
+
+Running tests on vKMS is essencially the same thing, with the advantage you don't need the display in virtme, since vKMS is virtual.
+
+Disable all other displays and leave vKMS only in the kernel:
+
+```
+CONFIG_DRM_VIRTIO_GPU=n
+CONFIG_DRM_VKMS=y
+```
+
+Launch virtme:
+
+```
+$(host) virtme-run --rwdir /tmp --kdir $KDIR --qemu-opts $MEM_CPU
+```
+
+And you can run tests as usuall.
+
+# Running kmscube on virtme
+
+## Install kmscube and its dependencies
+
+```
+$(host) git clone https://gitlab.freedesktop.org/mesa/kmscube.git
+$(host) cd kmscube
+
+# Check .gitlab-ci.yml for updated dependency list
+$(host) sudo apt install \
+                    build-essential \
+                    pkg-config \
+                    libdrm-dev \
+                    libgbm-dev \
+                    libegl1-mesa-dev \
+                    libgles2-mesa-dev \
+                    libgstreamer1.0-dev \
+                    libgstreamer-plugins-base1.0-dev \
+                    gstreamer1.0-plugins-base \
+                    gstreamer1.0-plugins-base-apps \
+                    ninja-build \
+                    python3 python3-pip \
+                    libpng-dev
+
+$(host) meson build
+$(host) ninja -C build
+```
+
+## Launch virtme + kmscube
+
+```
+# NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
+$(host) virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+
+$(virtme) cd path/to/kmscube
+$(virtme) ./build/kmscube
+```
+
+[ Image https://people.collabora.com/~koike/kmscube.png ]
+
+# Running kms-quads on virtme
+
+## Install kms-quads and its dependencies
+
+```
+$(host) git clone https://gitlab.freedesktop.org/daniels/kms-quads.git
+$(host) cd kms-quads
+$(host) meson build
+$(host) ninja -C build
+
+## Launch virtme + kms-quads
+
+```
+# NOTE: `CONFIG_DRM_VIRTIO_GPU=y` must be enabled in the kernel config.
+$(host) virtme-run --graphics --kdir $KDIR --kopt="console=ttyS0" --qemu-opts $MEM_CPU -vga virtio -serial mon:stdio
+
+$(virtme) cd path/to/kms-quads
+$(virtme) TTYNO=1 ./build/kms-quads
+```
+
+[ Image https://people.collabora.com/~koike/kms-quads.png ]
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