Permalink
Fetching contributors…
Cannot retrieve contributors at this time
36 lines (25 sloc) 2.06 KB

Porting Snabb Switch

Snabb Switch targets Linux/x86-64 on the master branch. The source code includes device drivers, assembler code, and optimization for specific CPU families.

You are welcome to port Snabb Switch to a new platform. To do this you can create a branch for your port and advertise this in branches.md. See below for some technical tips.

Currently there is no roadmap for supporting more platforms on the master branch. The first step in this direction would be to have a well-maintained port that is important for users.

The master branch accepts code that is specific to Linux/x86-64. It does not accept code intended for other platforms.

Technical tips

Here are a few challenges you are likely to encounter when porting Snabb Switch:

  • The memory module encodes the physical address of DMA memory into its virtual address using a 64-bit tagging scheme. This would need to be adapted for a 32-bit CPU.
  • Device drivers depend on allocating physically contiguous memory in blocks of at least 10KB.
  • Virtio-net code assumes a strict (x86-like) memory model that does not reorder stores. If your processor provides a more relaxed memory model then additional hardware memory barrier operations will be needed.
  • The shm/counter mechanism assumes that the processor loads and stores 64-bit values atomically. If your processor does not provide atomic 64-bit loads and stores then additional synchronization may be needed.
  • Certain optimizations depend on specific instruction set extensions such as AVX2. These optimizations may need to be ported in order to achieve adequate performance. (Particularly: multiple SIMD-optimized IP checksum routines.)
  • Certain functions may only be available platform-specific optimized variants. You would either need to live without these routines, or write a generic fallback routine, or write a new optimized variant. (Particularly: AES-GCM encryption with Intel AES-NI instructions.)

Like we said: Snabb Switch is a low-level piece of software. Portability is important but simplicity and performance are urgent.

Good luck!