Talk contents:

 - What precisely is offered by RISC-V?

 - Bootstrapping Fedora.

 - The state of RISC-V software development and the community.

 - Are open source ISAs in Red Hat's future?

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Instructions:

fixed size 32 bit instructions
compressed instructions extension
32 general purpose registers
32 floating point registers (extension)
zero register
always little-endian
influenced by MIPS
proven to be patent-free

Boring:

Micro-architecture independent as far as possible
Macro-op fusion
No register windows, branch delay slots etc
Royalty free, no licensing

Specifications:

  User spec 2.0 -> 2.1
  Priv spec 1.7 -> 1.9/2.0

4 open source core designs, Rocket, BOOM and two others
  Chisel generates Verilog
  Includes cache hierarchy
  Includes coherence between L2 caches
  Parameterized
  Targets C++ (simulation), FPGA or ASIC
  Proprietary tools needed if you go FPGA or ASIC route

Emulators

Toolchain

External projects:
  LowRISC = "RPi for grown-ups"
  SiFive
  Many FPGA implementations
  Lots of research groups
  Lots of small dev groups

Some large companies looking: NVidia, Google, AMD, HPE, IBM, Mellanox,
Microsemi, Microsoft, WD, ...

Missing bits:
  PLIC (coming)
  any other sort of hardware, serial, ethernet, display, SATA, DDR, ...
  PCI (SiFive have done some work)
  much of this is filled in with proprietary "IP"
  "Minion cores"

Virtualization
  Bonzini

What else goes into a server?
  BMC management
  standard boot environment (like SBBR on ARM)
  &c

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Fedora -- Demo

Fedora
  Explain why:
    Current software is crap
    Busybox
    Cross-compilers
    Basically an embedded system

Aims

Scope

Four stage bootstrap process
  Stage 3 is a "hack job" containing a mix of cross-compiled
  packages built on the host, layered with "--nodeps"-installed RPMs on top.

  Stage 4 is the clean image built entirely from RPMs, with all
  dependencies satisfied and all files controlled by RPM.

  The bootstrap process has generally speaking been quite easy (just
  tedious and slow because it all happens under emulation).

  All the complicated bits (ie. kernel, toolchain) were done already
  upstream and there haven't been any packages that were difficult to
  get working.

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RISC-V software development and the community

  Lots of momentum.  Considerably more realistic than previous
  open ISA efforts.

  Friendly and helpful upstream community.

  Far too many of non-upstream forks around.

  Some concerns about changes/instability in the architecture, but
  at least for userspace things seem pretty solid.

  Really needs virtio support.  Someone from the Fedora community
  is looking into this.

  Fedora community have been very active with packaging.

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What does this mean for Red Hat?













Summary and questions