Go on Fuchsia

To build a toolchain on Linux for Fuchsia, first follow the instructions on

https://fuchsia.googlesource.com/manifest/

Then,

• Set the SDK environment variable to the location of the Fuchsia SDK: If you downloaded fuchsia to your ${HOME} directory:

  export SDK=${HOME}/fuchsia/buildtools
  

• Identify where a host version of go exists, with:

  export GOROOT_BOOTSTRAP=`path to directory containing go`
  

  On my machine, which go returned /usr/lib/golang/bin/go, so I set GOROOT_BOOTSTRAP=/usr/lib/golang/

• Build Go in fuchsia/third_party/go/src using

  GOOS=fuchsia CC_FOR_TARGET=../misc/fuchsia/clangwrap.sh ./make.bash
  

• To build a program, junk.go in go/src, use:

  GOOS=fuchsia ../bin/go build junk.go
  

  This program can be put in a bootfs and run on qemu with:

  echo bin/junk=junk > junk.manifest
  fuchsia/buildtools/mkbootfs -o junk.bootfs junk.manifest
  ./scripts/run-zircon-x64 -x path/to/fuchsia/third_party/go/src/junk.bootfs
  

  A cgo variant can be build by adding CGO_ENABLED=1 to both the make.bash command and the go build command.

• To build a program using just the zircon prebuild toolchain (useful for debugging if the fuchsia sysroot is out of sync with your zircon) set the environment variable ZIRCON to the location of your zircon and build with the gccwrap.sh script:

  ZIRCON=$HOME/zircon CGO_ENABLED=1 CC_FOR_TARGET=$(pwd)/../misc/fuchsia/gccwrap.sh GOOS=fuchsia ./make.bash