Cobham Gaisler is a world leader in embedded computer systems for harsh environments, with footprints in many parts of the solar system. We provide the full ecosystem to support digital hardware design for mission critical System-on-a-Chip solutions. The IP cores and development tools support processors based on the SPARC and RISC-V architectures. In addition to this, a number of standard components are available.

NOEL-PF

Introduction

The NOEL-V processor and the GRLIB IP library has support for Microchip PolarFire FPGAs. This support consists of a techmap layer that wraps specific technology elements such as memory macros and pads. GRLIB also contains a template designs for developments boards such as the PolarFire FPGA Splash Kit and infrastructure that automatically builds project files for Libero SoC and synthesis tools such as Mentor Precision Hi-Rel and Synopsys Synplify Premier. More information about GRLIB and Cobham Gaisler IP cores is available on the SoC library page.

NOEL-PF board

Example designs

Cobham Gaisler provides prebuilt bitstreams of the PolarFire FPGA Splash Kit NOEL-V template design. These bitstreams are intended for evaluation of software running on a NOEL-V SoC. To evaluate these designs, the following items are required:

The example design range is called NOEL-PF-EX:

Software components and downloads for NOEL-PF:

NOEL-ARTYA7

IntroductionNOEL-ARTYA7 board

The NOEL-V processor and the GRLIB IP library has support for Xilinx Artix-7 devices. This support consists of a techmap layer that wraps specific technology elements such as memory macros and pads. GRLIB also contains a template designs for developments boards such as the  Arty A7: Artix-7 FPGA Development Board (A7-100T version) and infrastructure that automatically builds project files for Xilinx Vivado and synthesis tools such as Mentor Precision Hi-Rel and Synopsys Synplify Premier. More information about GRLIB and Cobham Gaisler IP cores is available on the SoC library page.

Example designs

Cobham Gaisler provides prebuilt bitstreams of the  Arty A7: Artix-7 FPGA Development Board NOEL-V template design. These bitstreams are intended for evaluation of software running on a NOEL-V SoC. To evaluate these designs, the following items are required:

The example design range is called NOEL-ARTYA7-EX:

Software components and downloads for NOEL-ARTYA7:

NOEL-XCKU

Introduction

The NOEL-V processor and the GRLIB IP library has support for Xilinx Kintex Ultrascale devices. This support consists of a techmap layer that wraps specific technology elements such as memory macros and pads. GRLIB also contains a template designs for developments boards such as the Xilinx Kintex UltraScale FPGA KCU105 Evaluation Kit and infrastructure that automatically builds project files for Xilinx Vivado and synthesis tools such as Mentor Precision Hi-Rel and Synopsys Synplify Premier. More information about GRLIB and Cobham Gaisler IP cores is available on the SoC library page.

NOEL-V-XCKU Board

Example designs

Cobham Gaisler provides prebuilt bitstreams of the Xilinx Kintex UltraScale FPGA KCU105 Evaluation Kit NOEL-V template design. These bitstreams are intended for evaluation of software running on a NOEL-V SoC. To evaluate these designs, the following items are required:

The example design range is called NOEL-XCKU-EX:

Software components for NOEL-XCKU:

NOEL-V Processor

IntroductionNOEL-V

The NOEL-V is a synthesizable VHDL model of a processor that implements the RISC-V architecture. The processor is the first released model in Cobham Gaisler's RiSC-V line of processors that complement the LEON line of processors.

The NOEL-V can be implemented as a dual-issue processor, allowing up to two instructions per cycle to be executed in parallel. To support the instruction issue rate of the pipeline, the NOEL-V has advanced branch prediction capabilities. The cache controller of the NOEL-V supports a store buffer FIFO with one cycle per store sustained throughput, and wide AHB slave support to enable fast stores and fast cache refill.

The NOEL-V is interfaced using the AMBA 2.0 AHB bus (subsystem with Level-2 cache and AXI4 backend is also available) and supports the IP core plug&play method provided in the Cobham Gaisler IP library (GRLIB). The processor can be efficiently implemented on FPGA and ASIC technologies and uses standard synchronous memory cells for caches and register file.

The NOEL-V processor has the following features:

  • RISC-V 64-bit architecture, 32-bit version scheduled for 2020
  • Hardware multiply and divide units
  • Compressed (16 bit) instruction support
  • Atomic instruction extension
  • 32/64 bit floating point extensions using non-pipelined area efficient FPU or high-performance fully pipelined IEEE-754 FPU
  • Machine, supervisor and user mode. RISC-V standard MMU with configurable TLB.
  • User level interrupts
  • RISC-V standard PLIC
  • RISC-V standard PMP (physical memory protection)
  • RISC-V standard external debug support
  • Advanced dual-issue in-order pipeline
  • Dynamic branch prediction, branch target buffer and return address stack
  • Four full ALUs, two of them late in the pipeline to reduce stalls
  • Separate instruction and data L1 cache (Harvard architecture) with snooping
  • Optional L2 cache: 256-bit internal, 1-4 ways, 16 KiB - 8 MiB
  • Native AMBA 2.0 AHB bus interface, 32-, 64- or 128-bit wide.
    • Subsystem including processor and Level-2 cache with AXI4 backend also available.
  • Robust and fully synchronous single-edge clock design
  • Extensively configurable
  • Large range of software tools: compilers, kernels and debug monitors
  • High Performance*: CoreMark: 4.03** / 4.69*** CoreMark/MHz
    *For HPP64 configuration. CoreMark score varies with processor configuration, microarchitectural changes, and toolchains. The CoreMark score is preliminary and will be updated for the v4 and v5 milestones.
    **-march=rv64im -mabi=lp64 -O2 -funroll-all-loops -funswitch-loops -fgcse-after-reload -fpredictive-commoning -mtune=sifive-7-series

    -finline-functions -fipa-cp-clone -falign-functions=8 -falign-loops=8 -falign-jumps=8 --param max-inline-insns-auto=20 using GCC 9.2.0 under RTEMS 5
    *** Using "#define ee_u32 int32_t" in core_portme.h, as is common for 64 bit RISC-V.
  • Synthesis

    The NOEL-V processor can be synthesized with common synthesis tools such as Xilinx Vivado, Synplify, and Synopsys DC. The processor model is highly portable between different implementation technologies.

    Software development

    The NOEL-V processor implements the RISC-V ISA which means that compilers and kernels for RISC-V can be used with NOEL-V (kernels will need a NOEL-V BSP). To simplify software development, Cobham Gaisler provides several prebuilt toolchains. Currently, the NOEL-V processor is supported by pre-built RTEMS and Linux toolchains. Cobham Gaisler provides VxWorks 7 BSP for NOEL-V under commercial license. Over time, the NOEL-V software support will be extended to the same level of support that exists for the LEON line of processors.

    The GRMON monitor interfaces to the NOEL-V on-chip debug support unit, implementing a large range of debug functions including GDB support for source level debugging.

    Configurations

    The NOEL-V processor core is available as part of a subsystem that also contains system peripherals. The subsystem can be configured to use the processor configurations listed in the table below. The configurations listed below are the ones recommended by Cobham Gaisler since they are covered by regression tests. Software toolchains provided by Cobham Gaisler are developed and built considering the same configurations. It is also possible to tailor additional configuration settings to create custom processor configurations by editing the VHDL generic (configuration parameter) assignments in the subsystem.

    ConfigurationISA*PipelineCacheMMUPMPFPUNoteAvailbility
    TIN32 RV32IM single issue no no no no Tiny configuration. Milestone v4
    MIN32 RV32IMAC single issue yes no yes no Minimal 32-bit configuration Milestone v4
    MIN64 RV64IMAC single issue yes no yes no Minimal 64-bit configuration Milestone v4
    GPP32 RV32GCHN single or dual issue yes yes yes GRFPU or NanoFPU General purpose 32-bit configuration Milestone v4
    GPP64 RV64GCHN single or dual issue yes yes yes GRFPU or NanoFPU General purpose 64-bit configuration Milestone v4
    HPP32 RV32GCHN dual issue yes yes yes GRFPU or NanoFPU High-performance 32-bit configuration Milestone v4
    HPP64 RV64GCHN dual issue yes yes yes GRFPU or NanoFPU High-performance 64-bit configuration Milestone v3

    Note: Configurations were updated 2020-11-12
    Note*: Key for ISA column:

    • RV32I - 32-bit Base Integer instructions
    • RV64I - 64-bit Base Integer instructions
    • M - Hardware support for multiply and division
    • A - Atomics
    • FD - Single/Double Floating Point
    • G - short for IMAFD
    • C - Compressed
    • H - Hardware hypervisor support
    • N - User-level interrupts

    The current release of NOEL-V has the following limitations:

    • Does not support the H, C, N and B extensions (see Milestone table below)
    • Only NanoFPU is supported.
    • The model cannot be implemented with fault-tolerance features enabled. Fault tolerance features can be enabled, as applicable and following the v4 milestone, for all the configurations above.

    Note: The standard configurations may be extended when additional extensions are supported by NOEL-V. For example, the Zbb extension may become part of the standard configurations in the future.

    Availability

    NOEL-V is part of the GRLIB IP Library from release 2020.2 There are also pre-built FPGA development board bitstreams available. Additional features for the NOEL-V processor will become available as part of milestone releases. The table below shows the planned milestones. Please note that the future milestone features and dates are tentative.

    MilestoneDescriptionDate
    v0 First RV64IMC release. Available as NOEL-XCKU example design. 2019-Dec
    v1 - v2

    Source release to first adopters, with the following features:

    • RV64IMA
    • VIPT cache
    2020-Apr
    v3

    The v3 release is the first generally available source release.

    Allows to create SoCs equivalent to LEON3/4/5 systems in terms of functionality:

    • RV64G (initial FD support)
    • FD extension (experimental - not fully verified)
    • A extension and multi-core support
    • Improved debug interface. Breakpoint and watchpoint triggers.
    • Performance counters (internal) and external event signals
    Support for HPP64 configuration.
    2020-Jul
    v4

    The v4 release introduces configurations that are suitable for more FPGA implementations
    (requiring fewer logic resources to implement the processor core).

    New functionality:

    • FD extension (NanoFPU)

    Support for TIN32, MIN32, GPP32, GPP64, HPP32 configurations.

    2020-Dec
    v5

     The v5 release adds fault-tolerance features and performance improvements:

    • Release of fault-tolerance support
    • FT adaptations to specific target technologies.
    • Multi-port bus connection between processor core and L2 cache
    • H extension
    • N extension
    • Zbb extension
    • GRFPUnv support
    2021-Jul
     v6 - ..

     Features under consideration for the v6 release and beyond include:

    • Additional subset(s) of B extension
    • P and V extensions
    • Support for more resource efficient floating-point implementations
     

    The NOEL-V is part of Cobham Gaisler's free open source GRLIB IP Library (the pipelined GRFPU5 is a commercial-only offering and will not be included in the free open source distribution). NOEL-V is also available under a low-cost commercial license, allowing it to be used in any commercial application. The commercial NOEL-V license includes:

    • High-performance pipeline GRFPU5 floating-point unit
    • The L2CACHE Level-2 cache controller
    • GRIOMMU IO memory management unit
    • Additional peripheral IP as described in the GRLIB IP Core User's Manual

    Demonstration systems and documentation

    GRLIB IP Library

    NOEL-V documentation is available in the GRLIB IP Library User's Manual - NOEL-V subsystem.

    FPGA programming files are also available for the following FPGA boards:

    • Digilent Arty-A7: NOEL-ARTYA7 example designs
    • Microsemi PolarFire Splash Kit: NOEL-PF example designs
    • Xilinx KCU105: NOEL-XCKU example designs

    Community

    Cobham Gaisler AB maintains a Discourse forum for those interested in the open source company's processor products.