start fuchsia in an emulator
usage: fx emu [-a <mode>] [-c <text>] [-N [-I <ifname>]] [-u <path>] [-v <build_variant>] [-g <port> [-r <fps>] [-t <cmd>]] [-x <port> [-X <directory>]] [-e <directory>] [-w <size>] [-s <cpus>] [-m <mb>] [-k <authorized_keys_file>] [-K <kernel_image>] [-z <zbi_image>] [-f <fvm_image>] [-p mouse|touch] [-H|--headless] [--audio] [--hidpi-scaling] [--software-gpu] [--debugger]
-a <mode> acceleration mode (auto, off, kvm, hvf, hax), default is auto
-c <text> append item to kernel command line
-ds <size> extends the fvm image size to <size> bytes. Default is twice the original size
-N run with emulated nic via tun/tap
-I <ifname> uses the tun/tap interface named ifname
-u <path> execute emu if-up script, default: linux: no script, macos: tap ifup script.
-v <build_variant> uses the build system variant to modify the total memory.
-e <directory> location of emulator, defaults to looking in prebuilt/third_party/aemu/PLATFORM
-g <port> enable gRPC service on port to control the emulator, default is 5556 when WebRTC service is enabled
-r <fps> webrtc frame rate when using gRPC service, default is 30
-t <cmd> execute the given command to obtain turn configuration
-x <port> enable WebRTC HTTP service on port
-X <directory> location of grpcwebproxy, defaults to looking in prebuilt/third_party/grpcwebproxy
-w <size> window size, default is 1280x800
-s <cpus> number of cpus, 1 for uniprocessor
-m <mb> total memory, in MB
-k <authorized_keys_file> SSH authorized keys file, otherwise defaults to ~/.ssh/fuchsia_authorized_keys
-K <kernel_image> path to image to use as kernel, defaults to kernel generated by the current build.
-z <zbi_image> path to image to use as ZBI, defaults to zircon-a generated by the current build.
-Z <zbi tool> path to a version of the `zbi` tool to use; defaults to the one in the current build directory.
-f <fvm_image> path to full FVM image, defaults to image generated by the current build.
-F <fvm tool> path to a version of the `fvm` tool to use; defaults to the one in the current build directory.
-A <arch> architecture of images (x64, arm64), default is the current build.
-p mouse|touch set pointing device used on emulator: mouse or multitouch screen; defaults to mouse.
-H|--headless run in headless mode
--audio run with audio hardware added to the virtual machine
--hidpi-scaling enable pixel scaling on HiDPI devices
--host-gpu run with host GPU acceleration
--software-gpu run without host GPU acceleration
--debugger pause on launch and wait for a debugger process to attach before resuming
--no-build do not attempt to build the fvm and zbi tools and the zbi image