# Fuchsia support

For information about checking out and building Fuchsia see
[Getting Started](https://fuchsia.googlesource.com/docs/+/master/getting_started.md)
and [Soure Code](https://fuchsia.googlesource.com/docs/+/master/development/source_code/README.md).
Image needs to be configured with sshd support:
```
fx set x64 --packages garnet/packages/products/sshd
fx full-build
```

You need to build fuchsia for both arm64 and amd64:

```
fx set arm64 --packages garnet/packages/products/sshd
fx full-build
```

Syscall descriptions live in the `sys/fuchsia` folder. To update a syscall, you need to modify the `.txt` file that contains it, make sure your new definition matches the one in zircon's [syscalls.abigen](https://fuchsia.googlesource.com/zircon/+/HEAD/system/public/zircon/syscalls.abigen) file. **If the syscall was used in `executor/common_fuchsia.h`, you need to update the usages there as well**. FIDL definitions do not need manual updating because they are extracted automatically with the commands below.

Once you updated the syscalls definitions, everything can be regenerated by running:

```
make extract TARGETOS=fuchsia SOURCEDIR=/path/to/fuchsia/checkout
make generate
```

To build binaries:
```
make TARGETOS=fuchsia TARGETARCH=amd64 SOURCEDIR=/path/to/fuchsia/checkout
```

Run `syz-manager` with a config along the lines of:
```
{
	"name": "fuchsia",
	"target": "fuchsia/amd64",
	"http": ":12345",
	"workdir": "/workdir.fuchsia",
	"kernel_obj": "/fuchsia/out/build-zircon/build-x64",
	"syzkaller": "/syzkaller",
	"image": "/fuchsia/out/x64/out/build/images/fvm.blk",
	"sshkey": "/fuchsia/out/x64/ssh-keys/id_ed25519",
	"reproduce": false,
	"cover": false,
	"procs": 8,
	"type": "qemu",
	"vm": {
		"count": 10,
		"cpu": 4,
		"mem": 2048,
		"kernel": "/fuchsia/out/build-zircon/build-x64/zircon.bin",
		"initrd": "/fuchsia/out/x64/bootdata-blob.bin"
	}
}
```


## How to generate syscall description for FIDL

Syscall descriptions for FIDL are automatically generated as part of `make extract` as described above.

However, if you wish to manually generate syscall descriptions for a given `.fidl` file, do the following.

FIDL files should first be compiled into FIDL intermediate representation (JSON) files using `fidlc`:

```bash
/fuchsia/out/x64/host_x64/fidlc --json /tmp/io.json --files /fuchsia/zircon/system/fidl/fuchsia-io/io.fidl
```

Then run FIDL compiler backend `fidlgen` with syzkaller generator, which compiles a FIDL IR file into a syscall description file:

```bash
/fuchsia/out/x64/host_x64/fidlgen -generators syzkaller -json /tmp/io.json -output-base fidl_io -include-base fidl_io
```
## Running syz-ci locally

To run `syz-ci` locally for Fuchsia, you need:

- Go 1.10 toolchain (in `/go1.10` dir in the example below)
- bootstrapped Fuchsia checkout (in `/bootstrap/fuchsia` dir in the example below)
- bootstrap `syz-ci` binary (in the current dir, build with `make ci`)
- `syz-ci` config similar to the one below (in `ci.cfg` file in the current dir)

```
{
	"name": "testci",
	"http": ":50000",
	"manager_port_start": 50001,
	"goroot": "/go1.10",
	"syzkaller_repo": "https://github.com/google/syzkaller.git",
	"managers": [
		{
			"name": "fuchsia",
			"repo": "https://fuchsia.googlesource.com",
			"manager_config": {
				"target": "fuchsia/amd64",
				"type": "qemu",
				"cover": false,
				"procs": 8,
				"vm": {
					"count": 4,
					"cpu": 4,
					"mem": 1024
				}
			}
		}
	]
}
```

Run `syz-ci` as:
```
SOURCEDIR=/bootstrap/fuchsia ./syz-ci -config ci.cfg
```

## Troubleshooting

While running the `make extract` step, it's possible that the fidl definitions
are not up to date. It could happen that they have been removed or renamed.

If this is the case, you would see an error mentioning that the fidl.json file
could not be found:

```
go generate ./sys/fuchsia
cannot find /path-to-fuchsia/out/x64/fidling/gen/zircon/public/fidl/zircon-ethernet/zircon-ethernet.fidl.json
exit status 1
```

You can search for the string in the fuchsia repos or in the code-review tool to
see what happened to it. If the fidl interface was renamed or removed, you
should update `sys/fuchsia/fidlgen/main.go` to reflect this change, and remove the
stale autogenerated files.