zircon/docs/getting_started.md - fuchsia - Git at Google

 # Quick Start Recipes

 ## Checking out the Zircon source code

 *** note
 NOTE: The Fuchsia source includes Zircon. See Fuchsia's
 [Getting Started](https://fuchsia.googlesource.com/fuchsia/+/master/docs/getting_started.md)
 doc. Follow this doc to work on only Zircon.
 ***

 The Zircon Git repository is located
 at: https://fuchsia.googlesource.com/zircon

 To clone the repository, assuming you setup the $SRC variable
 in your environment:
 ```shell
 git clone https://fuchsia.googlesource.com/zircon $SRC/zircon
 ```

 For the purpose of this document, we will assume that Zircon is checked
 out in $SRC/zircon and that we will build toolchains, QEMU, etc alongside
 that.  Various ninja invocations are presented with a "-j32" option for
 parallelization.  If that's excessive for the machine you're building on,
 try -j16 or -j8.

 ## Preparing the build environment

 ### Ubuntu

 On Ubuntu this should obtain the necessary pre-reqs:
 ```
 sudo apt-get install texinfo libglib2.0-dev autoconf libtool bison libsdl-dev build-essential
 ```

 ### macOS
 Install the Xcode Command Line Tools:
 ```
 xcode-select --install
 ```

 Install the other pre-reqs:

 * Using Homebrew:
 ```
 brew install wget pkg-config glib autoconf automake libtool
 ```

 * Using MacPorts:
 ```
 port install autoconf automake libtool libpixman pkgconfig glib2
 ```

 ## Install Toolchains and Prebuilts

 If you're developing on Linux or macOS, there are prebuilt toolchain binaries available.
 Just run this script from your Zircon working directory:

 ```
 ./scripts/download-prebuilt
 ```

 If you would like to build the toolchains yourself, follow the instructions later
 in the document.

 ## Build Zircon

 Build results will be in $SRC/zircon/build-zircon.

 ```
 cd $SRC/zircon
 gn gen build-zircon

 # for both aarch64 and x64
 ninja -C build-zircon

 # for aarch64
 ninja -C build-zircon arm64

 # for x64
 ninja -C build-zircon x64
 ```

 ### Using Clang

 To build Zircon using Clang as the target toolchain, set the
 `variants = [ "clang" ]` build argument when invoking GN.

 ```
 cd $SRC/zircon
 gn gen build-zircon --args='variants = [ "clang" ]'

 # for both aarch64 and x64
 ninja -C build-zircon

 # for aarch64
 ninja -C build-zircon arm64

 # for x64
 ninja -C build-zircon x64
 ```

 ## Building Zircon for all targets

 ```
 # The -r enables release builds as well
 ./scripts/buildall -r
 ```

 Please build for all targets before submitting to ensure builds work
 on all architectures.

 ## QEMU

 You can skip this if you're only testing on actual hardware, but the emulator
 is handy for quick local tests and generally worth having around.

 See [QEMU](qemu.md) for information on building and using QEMU with zircon.


 ## Build Toolchains (Optional)

 If the prebuilt toolchain binaries do not work for you, you can build your
 own from vanilla upstream sources.

  * The GCC toolchain is used to build Zircon by default.
  * The Clang toolchain is used to build Zircon if you build with
    `variants = [ "clang" ]` or `variants = [ "asan" ]`.
  * The Clang toolchain is also used by default to build host-side code, but
    any C++14-capable toolchain for your build host should work fine.

 Build one or the other or both, as needed for how you want build Zircon.

 ### GCC Toolchain

 We use GNU `binutils` 2.30(`*`) and GCC 8.2(`**`), configured with
 `--enable-initfini-array --enable-gold`, and with `--target=x86_64-elf
 --enable-targets=x86_64-pep` for x86-64 or `--target=aarch64-elf` for ARM64.

 For `binutils`, we recommend `--enable-deterministic-archives` but that switch
 is not necessary to get a working build.

 For GCC, it's necessary to pass `MAKEOVERRIDES=USE_GCC_STDINT=provide` on the
 `make` command line.  This should ensure that the `stdint.h` GCC installs is
 one that works standalone (`stdint-gcc.h` in the source) rather than one that
 uses `#include_next` and expects another `stdint.h` file installed elsewhere.

 Only the C and C++ language support is required and no target libraries other
 than `libgcc` are required, so you can use various `configure` switches to
 disable other things and make your build of GCC itself go more quickly and use
 less storage, e.g. `--enable-languages=c,c++ --disable-libstdcxx
 --disable-libssp --disable-libquadmath`.  See the GCC installation
 documentation for more details.

 You may need various other `configure` switches or other prerequisites to
 build on your particular host system.  See the GNU documentation.

 (`*`) The `binutils` 2.30 release has some harmless `make check` failures in
 the `aarch64-elf` and `x86_64-elf` configurations.  These are fixed on the
 upstream `binutils-2_30-branch` git branch, which is what we actually build.
 But the 2.30 release version works fine for building Zircon; it just has some
 spurious failures in its own test suite.

 (`**`) As of 2008-6-15, GCC 8.2 has not been released yet.  There is no
 released version of GCC that works for building Zircon without backporting
 some fixes.  What we actually use is the upstream `gcc-8-branch` git branch.

 ### Clang/LLVM Toolchain

 We use a trunk snapshot of Clang and update to new snapshots frequently.  Any
 build of recent-enough Clang with support for `x86_64` and `aarch64` compiled
 in should work.  You'll need a toolchain that also includes the runtime
 libraries.  We normally also use the same build of Clang for the host as well
 as for the `*-fuchsia` targets.  See
 [here](https://fuchsia.googlesource.com/fuchsia/+/master/docs/development/build/toolchain.md)
 for details on how we build Clang.

 ### Set up build arguments for toolchains

 If you're using the prebuilt toolchains, you can skip this step, since
 the build will find them automatically.

 Set the build argument that points to where you installed the toolchains:

 ```gn
 # in args.gn or passed to --args
 clang_tool_dir = "<absolute path to>/clang-install/bin/"
 gcc_tool_dir = "<absolute path to>/gcc-install/bin/"
 ```

 Note that `*_tool_dir` should have a trailing slash. If the `clang` or
 `gcc` in your `PATH` works for Zircon, you can just use empty prefixes.

 ## Copying files to and from Zircon

 With local link IPv6 configured, the host tool ./build-ARCH/tools/netcp
 can be used to copy files.

 ```
 # Copy the file myprogram to Zircon
 netcp myprogram :/tmp/myprogram

 # Copy the file myprogram back to the host
 netcp :/tmp/myprogram myprogram
 ```

 ## Including Additional Userspace Files

 The Zircon build creates a bootfs image containing necessary userspace components
 for the system to boot (the device manager, some device drivers, etc).  The kernel
 is capable of including a second bootfs image which is provided by QEMU or the
 bootloader as a ramdisk image.

 To create such a bootfs image, use the zbi tool that's generated as part of
 the build.  It can assemble a bootfs image for either source directories (in which
 case every file in the specified directory and its subdirectories are included) or
 via a manifest file which specifies on a file-by-file basis which files to include.

 ```
 $BUILDDIR/tools/zbi -o extra.bootfs @/path/to/directory

 echo "issue.txt=/etc/issue" > manifest
 echo "etc/hosts=/etc/hosts" >> manifest
 $BUILDDIR/tools/zbi -o extra.bootfs manifest
 ```

 On the booted Zircon system, the files in the bootfs will appear under /boot, so
 in the above manifest example, the "hosts" file would appear at /boot/etc/hosts.

 ## Network Booting

 Network booting is supported via two mechanisms: Gigaboot and Zirconboot.
 Gigaboot is an EFI based bootloader whereas zirconboot is a mechanism that
 allows a minimal zircon system to serve as a bootloader for zircon.

 On systems that boot via EFI (such as Acer and NUC), either option is viable.
 On other systems, zirconboot may be the only option for network booting.

 ### Via Gigaboot
 The [GigaBoot20x6](https://fuchsia.googlesource.com/fuchsia/+/master/zircon/bootloader) bootloader speaks a simple network boot protocol (over IPV6 UDP)
 which does not require any special host configuration or privileged access to use.

 It does this by taking advantage of IPV6 Link Local Addressing and Multicast,
 allowing the device being booted to advertise its bootability and the host to find
 it and send a system image to it.

 If you have a device (for example a Broadwell or Skylake Intel NUC) running
 GigaBoot20x6 first create a USB drive [manually](https://fuchsia.googlesource.com/fuchsia/+/master/zircon/docs/targets/acer12.md#How-to-Create-a-Bootable-USB-Flash-Drive)
 or (Linux only) using the [script](https://fuchsia.googlesource.com/fuchsia/+/master/scripts/build-bootable-usb-gigaboot.sh).

 ```
 $BUILDDIR/tools/bootserver $BUILDDIR/zircon.bin

 # if you have an extra bootfs image (see above):
 $BUILDDIR/tools/bootserver $BUILDDIR/zircon.bin /path/to/extra.bootfs
 ```

 By default bootserver will continue to run and every time it observes a netboot
 beacon it will send the kernel (and bootfs if provided) to that device.  If you
 pass the -1 option, bootserver will exit after a successful boot instead.


 ### Via Zirconboot
 Zirconboot is a mechanism that allows a zircon system to serve as the
 bootloader for zircon itself. Zirconboot speaks the same boot protocol as
 Gigaboot described above.

 To use zirconboot, pass the `netsvc.netboot=true` argument to zircon via the
 kernel command line. When zirconboot starts, it will attempt to fetch and boot
 into a zircon system from a bootserver running on the attached host.

 ## Network Log Viewing

 The default build of Zircon includes a network log service that multicasts the
 system log over the link local IPv6 UDP.  Please note that this is a quick hack
 and the protocol will certainly change at some point.

 For now, if you're running Zircon on QEMU with the -N flag or running on hardware
 with a supported ethernet interface (ASIX USB Dongle or Intel Ethernet on NUC),
 the loglistener tool will observe logs broadcast over the local link:

 ```
 $BUILDDIR/tools/loglistener
 ```

 ## Debugging

 For random tips on debugging in the zircon environment see
 [debugging](debugging/tips.md).

 ## Contribute changes
 * See [contributing.md](contributing.md).
	# Quick Start Recipes

	## Checking out the Zircon source code

	*** note
	NOTE: The Fuchsia source includes Zircon. See Fuchsia's
	[Getting Started](https://fuchsia.googlesource.com/fuchsia/+/master/docs/getting_started.md)
	doc. Follow this doc to work on only Zircon.
	***

	The Zircon Git repository is located
	at: https://fuchsia.googlesource.com/zircon

	To clone the repository, assuming you setup the $SRC variable
	in your environment:
	```shell
	git clone https://fuchsia.googlesource.com/zircon $SRC/zircon
	```

	For the purpose of this document, we will assume that Zircon is checked
	out in $SRC/zircon and that we will build toolchains, QEMU, etc alongside
	that. Various ninja invocations are presented with a "-j32" option for
	parallelization. If that's excessive for the machine you're building on,
	try -j16 or -j8.

	## Preparing the build environment

	### Ubuntu

	On Ubuntu this should obtain the necessary pre-reqs:
	```
	sudo apt-get install texinfo libglib2.0-dev autoconf libtool bison libsdl-dev build-essential
	```

	### macOS
	Install the Xcode Command Line Tools:
	```
	xcode-select --install
	```

	Install the other pre-reqs:

	* Using Homebrew:
	```
	brew install wget pkg-config glib autoconf automake libtool
	```

	* Using MacPorts:
	```
	port install autoconf automake libtool libpixman pkgconfig glib2
	```

	## Install Toolchains and Prebuilts

	If you're developing on Linux or macOS, there are prebuilt toolchain binaries available.
	Just run this script from your Zircon working directory:

	```
	./scripts/download-prebuilt
	```

	If you would like to build the toolchains yourself, follow the instructions later
	in the document.

	## Build Zircon

	Build results will be in $SRC/zircon/build-zircon.

	```
	cd $SRC/zircon
	gn gen build-zircon

	# for both aarch64 and x64
	ninja -C build-zircon

	# for aarch64
	ninja -C build-zircon arm64

	# for x64
	ninja -C build-zircon x64
	```

	### Using Clang

	To build Zircon using Clang as the target toolchain, set the
	`variants = [ "clang" ]` build argument when invoking GN.

	```
	cd $SRC/zircon
	gn gen build-zircon --args='variants = [ "clang" ]'

	# for both aarch64 and x64
	ninja -C build-zircon

	# for aarch64
	ninja -C build-zircon arm64

	# for x64
	ninja -C build-zircon x64
	```

	## Building Zircon for all targets

	```
	# The -r enables release builds as well
	./scripts/buildall -r
	```

	Please build for all targets before submitting to ensure builds work
	on all architectures.

	## QEMU

	You can skip this if you're only testing on actual hardware, but the emulator
	is handy for quick local tests and generally worth having around.

	See [QEMU](qemu.md) for information on building and using QEMU with zircon.


	## Build Toolchains (Optional)

	If the prebuilt toolchain binaries do not work for you, you can build your
	own from vanilla upstream sources.

	* The GCC toolchain is used to build Zircon by default.
	* The Clang toolchain is used to build Zircon if you build with
	`variants = [ "clang" ]` or `variants = [ "asan" ]`.
	* The Clang toolchain is also used by default to build host-side code, but
	any C++14-capable toolchain for your build host should work fine.

	Build one or the other or both, as needed for how you want build Zircon.

	### GCC Toolchain

	We use GNU `binutils` 2.30(``) and GCC 8.2(`*`), configured with
	`--enable-initfini-array --enable-gold`, and with `--target=x86_64-elf
	--enable-targets=x86_64-pep` for x86-64 or `--target=aarch64-elf` for ARM64.

	For `binutils`, we recommend `--enable-deterministic-archives` but that switch
	is not necessary to get a working build.

	For GCC, it's necessary to pass `MAKEOVERRIDES=USE_GCC_STDINT=provide` on the
	`make` command line. This should ensure that the `stdint.h` GCC installs is
	one that works standalone (`stdint-gcc.h` in the source) rather than one that
	uses `#include_next` and expects another `stdint.h` file installed elsewhere.

	Only the C and C++ language support is required and no target libraries other
	than `libgcc` are required, so you can use various `configure` switches to
	disable other things and make your build of GCC itself go more quickly and use
	less storage, e.g. `--enable-languages=c,c++ --disable-libstdcxx
	--disable-libssp --disable-libquadmath`. See the GCC installation
	documentation for more details.

	You may need various other `configure` switches or other prerequisites to
	build on your particular host system. See the GNU documentation.

	(`*`) The `binutils` 2.30 release has some harmless `make check` failures in
	the `aarch64-elf` and `x86_64-elf` configurations. These are fixed on the
	upstream `binutils-2_30-branch` git branch, which is what we actually build.
	But the 2.30 release version works fine for building Zircon; it just has some
	spurious failures in its own test suite.

	(`**`) As of 2008-6-15, GCC 8.2 has not been released yet. There is no
	released version of GCC that works for building Zircon without backporting
	some fixes. What we actually use is the upstream `gcc-8-branch` git branch.

	### Clang/LLVM Toolchain

	We use a trunk snapshot of Clang and update to new snapshots frequently. Any
	build of recent-enough Clang with support for `x86_64` and `aarch64` compiled
	in should work. You'll need a toolchain that also includes the runtime
	libraries. We normally also use the same build of Clang for the host as well
	as for the `*-fuchsia` targets. See
	[here](https://fuchsia.googlesource.com/fuchsia/+/master/docs/development/build/toolchain.md)
	for details on how we build Clang.

	### Set up build arguments for toolchains

	If you're using the prebuilt toolchains, you can skip this step, since
	the build will find them automatically.

	Set the build argument that points to where you installed the toolchains:

	```gn
	# in args.gn or passed to --args
	clang_tool_dir = "<absolute path to>/clang-install/bin/"
	gcc_tool_dir = "<absolute path to>/gcc-install/bin/"
	```

	Note that `*_tool_dir` should have a trailing slash. If the `clang` or
	`gcc` in your `PATH` works for Zircon, you can just use empty prefixes.

	## Copying files to and from Zircon

	With local link IPv6 configured, the host tool ./build-ARCH/tools/netcp
	can be used to copy files.

	```
	# Copy the file myprogram to Zircon
	netcp myprogram :/tmp/myprogram

	# Copy the file myprogram back to the host
	netcp :/tmp/myprogram myprogram
	```

	## Including Additional Userspace Files

	The Zircon build creates a bootfs image containing necessary userspace components
	for the system to boot (the device manager, some device drivers, etc). The kernel
	is capable of including a second bootfs image which is provided by QEMU or the
	bootloader as a ramdisk image.

	To create such a bootfs image, use the zbi tool that's generated as part of
	the build. It can assemble a bootfs image for either source directories (in which
	case every file in the specified directory and its subdirectories are included) or
	via a manifest file which specifies on a file-by-file basis which files to include.

	```
	$BUILDDIR/tools/zbi -o extra.bootfs @/path/to/directory

	echo "issue.txt=/etc/issue" > manifest
	echo "etc/hosts=/etc/hosts" >> manifest
	$BUILDDIR/tools/zbi -o extra.bootfs manifest
	```

	On the booted Zircon system, the files in the bootfs will appear under /boot, so
	in the above manifest example, the "hosts" file would appear at /boot/etc/hosts.

	## Network Booting

	Network booting is supported via two mechanisms: Gigaboot and Zirconboot.
	Gigaboot is an EFI based bootloader whereas zirconboot is a mechanism that
	allows a minimal zircon system to serve as a bootloader for zircon.

	On systems that boot via EFI (such as Acer and NUC), either option is viable.
	On other systems, zirconboot may be the only option for network booting.

	### Via Gigaboot
	The [GigaBoot20x6](https://fuchsia.googlesource.com/fuchsia/+/master/zircon/bootloader) bootloader speaks a simple network boot protocol (over IPV6 UDP)
	which does not require any special host configuration or privileged access to use.

	It does this by taking advantage of IPV6 Link Local Addressing and Multicast,
	allowing the device being booted to advertise its bootability and the host to find
	it and send a system image to it.

	If you have a device (for example a Broadwell or Skylake Intel NUC) running
	GigaBoot20x6 first create a USB drive [manually](https://fuchsia.googlesource.com/fuchsia/+/master/zircon/docs/targets/acer12.md#How-to-Create-a-Bootable-USB-Flash-Drive)
	or (Linux only) using the [script](https://fuchsia.googlesource.com/fuchsia/+/master/scripts/build-bootable-usb-gigaboot.sh).

	```
	$BUILDDIR/tools/bootserver $BUILDDIR/zircon.bin

	# if you have an extra bootfs image (see above):
	$BUILDDIR/tools/bootserver $BUILDDIR/zircon.bin /path/to/extra.bootfs
	```

	By default bootserver will continue to run and every time it observes a netboot
	beacon it will send the kernel (and bootfs if provided) to that device. If you
	pass the -1 option, bootserver will exit after a successful boot instead.


	### Via Zirconboot
	Zirconboot is a mechanism that allows a zircon system to serve as the
	bootloader for zircon itself. Zirconboot speaks the same boot protocol as
	Gigaboot described above.

	To use zirconboot, pass the `netsvc.netboot=true` argument to zircon via the
	kernel command line. When zirconboot starts, it will attempt to fetch and boot
	into a zircon system from a bootserver running on the attached host.

	## Network Log Viewing

	The default build of Zircon includes a network log service that multicasts the
	system log over the link local IPv6 UDP. Please note that this is a quick hack
	and the protocol will certainly change at some point.

	For now, if you're running Zircon on QEMU with the -N flag or running on hardware
	with a supported ethernet interface (ASIX USB Dongle or Intel Ethernet on NUC),
	the loglistener tool will observe logs broadcast over the local link:

	```
	$BUILDDIR/tools/loglistener
	```

	## Debugging

	For random tips on debugging in the zircon environment see
	[debugging](debugging/tips.md).

	## Contribute changes
	* See [contributing.md](contributing.md).