NFU Specification

Simple overview:

• NFU server -- "adjacent" to IBP depot, runs NFU Ops
• NFU Op -- lightweight program, written in C, or Java, depending on server.
• NFU client -- initiates launch of an nfu Op and exchanges data with it.
• NFU API -- Two iotypes for data exchange between nfu_op and nfu_client:
  • IBP_VAL_[IN, OUT, INOUT]
    • variable/values exchanged directly between nfu client and nfu Op
  • IBP_REF_[RD, WR, RDWR]
    • NFU Server (not nfuOp) processes IBP Caps
    • E.G. _RD: client sends readCap to server, NFU server provides nfuOp a pointer to mmap of the allocation
    • nfuOp does not receive readCap string
• security issues
  • Java NFU server has VM isolation of nfuOp
  • UTK NFU server has option to run Cap as process to isolate nfuOp from server
  • UTK NFU server mmaps allocations from readCaps, i.e. nfuOp has no direct knowledge of allocation file names.
• compatibility issues:
  • Java NFU server currently has no way to run C nfuOps
  • if nfu server is not part of the ibp depot, then all IBP_REF_* exchanges need to be changed to IBP_VAL_* exchanges forcing the nfuOp to process IBP caps which would otherwise be processed by the nfuServer.
    • this disables 1/2 of the NFU api