# Adding new OS support

Here are the common parts of syzkaller to edit in order to make syzkaller support a new OS kernel. However, there may be some specific changes that will be required for a given kernel (for example, gathering coverage from a given kernel, or some errors that might pop up and give a hint about what to tweak).

## syz-executor

For each OS, there is this file `executor/executor_GOOS.h` where GOOS is the OS name. This file contains two important functions:

- `os_init` which is responsible for mapping a virtual address space for the calling process,
- `execute_syscall` which is responsible for executing system calls for a particular OS kernel.

These two functions, are called in `executor/executor.cc`, which is mainly responsible for executing the syscalls programs, and managing the threads in which the programs run.

`executor_GOOS.h` also contains functions related to that operating system such as functions that allow it to gather coverage information, detect bitness, etc. (Example: [executor_linux.h](/executor/executor_linux.h) ).

The intended function will be called according to the target kernel as defined by the macros in the `executor/executor.cc` file.

## Build files `pkg/`

- The OS name is added to `pkg/build/build.go` along with the supported architecture
- Creating a file that builds the image for the targeted kernel under `pkg/build/`. There is a file per each of the supported OSes by Syzkaller where the name pattern is `GOOS.go`.

- Adding the given target to the `s/makefile/Makefile/`.

## Report files `pkg/report/`

Creating a file that reports build errors  for the targeted kernel under `pkg/report/`. There is a file per each of the supported OSes by Syzkaller where the name pattern is `GOOS.go`.

## Editing `pkg/host/`

- implement `isSupported` function that returns true for a supported syscall, it is located under `pkg/host/GOOS`.

## Creating a file under `sys/GOOS/`

Creating a file `init.go` for the targeted kernel under `sys/GOOS/`that included the function `initTarget` that initializes the target and the different supported architectures.

## Editing `sys/syz-extract`

Adding the new kernel name with already existing supported kernels to the file `sys/syz-extract/extract.go`.

## Editing `sys/targets`

Adding the new kernel name with already existing supported kernels to the file `targets.go` which is located under`sys/targets`.

## Editing `vm/qemu`

Adding the new kernel name with already existing supported kernels to the file `qemo.go` which is located under `vm/qemu`.

## Syzkaller description & pseudo-syscalls

Check [descriptions](/docs/syscall_descriptions.md), and [pseudo-syscalls](/docs/pseudo_syscalls.md).