black-parrot-sdk / black-parrot-sdk

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The BlackParrot SDK is a collection of tools and example benchmark suites to demonstrate how to develop for the BlackParrot core. BlackParrot implements a standard RV64IMAFDMSU ISA and so is capable of running just about any program on top of Linux. However, due to the simulation overheads of running Linux, it's often useful to run programs baremetal. We provide a variety of convenient features for bare-metal programs, with and without accelerators attached.

Getting started

Quickstart: Download a pre-built toolchain (Alpha)

Pre-built programs and toolchains can be downloaded at this repo's releases page. These are intended for compute or bandwidth constrained users, as well as classes or labs which may not have the permissions required to install necessary pre-requisites. To use them instead of building the SDK yourself:

make checkout # initialize submodules
make pull_sdk # Download and unpack pre-built SDK

This will grab both the tools and a few pre-built benchmark suites. From there you should be able to build further programs using the tool installation. Toolchains were built on Ubuntu 20.04 using this image, but should run on any modern Linux platform. We welcome contributions for other images and scripts to build for other platforms.

Building the SDK

Before building the SDK, refer to the relevant section in the README on BlackParrot Simulation Environment for preparing required tools and libraries.

make checkout # initialize submodules
# Set whatever variables your platform requires in Makefile.platform
#   or select a pre-configured platform from {dromajo_cosim, zynqparrot}
make sdk  # you can use the -j N flag to parallelize
make prog # only makes a subset of programs. See Makefile for the full list of commands

For each suite in this directory, make <suite> will build the tests within and copy the resulting .riscv binaries to ./prog/suite/example.riscv

The build process tries to be intelligent and only rebuild if a submodule has changed since the last build. To forcibly build a test suite, use make <suite>_manual.

Libperch

libperch is the BlackParrot firmware library. It includes sample linker scripts for supported SoC platforms, start code for running bare-metal tests, emulation code for missing instructions and firmware routines for printing, serial input and output and program termination.

libperch is automatically compiled as part of the toplevel make sdk target. It is automatically installed to ./lib/. Users should link this library when compiling a new bare-metal program for BlackParrot.

PanicRoom (aka bsg_newlib)

PanicRoom is a port of newlib which packages a DRAM-based filesystem (LittleFS) along with a minimal C library. By only implementing a few platform level operations, PanicRoom provides an operational filesystem, eliminating the need for a complex host interface, It is automatically included with the standard toolchain build as riscv64-unknown-elf-dramfs-, allowing benchmarks such as SPEC to run with minimal host overhead. For an example of how to use PanicRoom, see lfs_demo in bp-demos

The SDK will install a program which allows you to convert a set of text files into the LitteFS filesystem.

Usage: dramfs_mklfs <block_size> <block_count> [input file(s)/dir(s)]
Example dramfs_mklfs 128 64 hello.txt > lfs.c

From there, you can simply compile the lfs.c along with your main program and you will have access to the filesystem using normal calls:

int main() {
    // Initialize LFS
    dramfs_init();

    // Read from a file
    FILE *hello = fopen("hello.txt", "r");
    if(hello == NULL)
      return -1;

    char c;
    while((c = fgetc(hello)) != '\n') {
      bp_cprint(c);
    }
    bp_cprint('\n');

    fclose(hello);
    bp_finish(0);
    return 0;
}

PanicRoom is also used for stdio operations like printf. So to use these functions you still need to generate a LittleFS configuration file(lfs.c) without any input files. You also need to call the dramfs_init function by building the start.S code in the perch directory with -D_DRAMFS flag alongside your program, or use the crt0.o generated at lib/ as the default start code, or simply call it at the beginning of the main function.

Building Linux

To build a SMP Linux executable for BlackParrot (make sure first to follow the above instructions for building the SDK):

make -j linux OPENSBI_NCPUS=<n>
./install/bin/dromajo --host --ncpus=<n> [--enable_amo] linux/linux.riscv # verify linux runs on the dromajo simulator

Note: When testing SMP Linux (ncpus > 1) in Dromajo, you may need to add the --enable_amo flag to turn on support for atomics in Dromajo, which are supported by the BlackParrot hardware.

For further information read the bp-linux README.

Adding a test

To add a new test to BlackParrot using our libraries is simple. Using our framework

  • add the new test C file in bp-demos/src
  • add the test to the test_list in bp-demos/Makefile.frag
  • execute make bp-demos at the sdk root directory This should build and install the test program to prog/bp-demos/foobar.riscv

If you want to use your own build structure, include ./Makefile.common to import notable BlackParrot directory names as well as put the compiler on your path. To build a program, use the following flags:

  • riscv64-unknown-elf-dramfs-gcc (for PanicRoom), riscv64-unknown-linux-gnu-gcc (for Linux)
  • -I$(BP_INCLUDE_DIR)
  • -L$(BP_LIB_DIR) -lperch
  • -T$(BP_LINKER_DIR)/riscv.ld

When you're done building your program, copy it into ./prog/custom/foobar.riscv or your favorite SUITE/PROG combination

Testing your test

RTL waveform debugging is hard. That's why, before we run new programs on BlackParrot, we want to run them in Dromajo to verify that the software is working. Luckily, we've already built Dromajo as part of make sdk. The version of Dromajo built has been modified to behave exactly as BlackParrot does and is found here: https://github.com/bsg-external/dromajo. There is further documentation on Dromajo in that repo.

./install/bin/dromajo --host [--enable_amo] [--ncpus=1] [--trace] ./prog/custom/foobar.riscv

will run your program. The --host options make Dromajo behave as BlackParrot, with a host interface emulating our Verilog testbench. Once Dromajo passes your test, you're ready to run on BlackParrot!

Debugging your test

Dromajo supports tracing. This option is enabled by adding --trace=0 to the dromajo invocation (0 indicates to start the trace after 0 instructions). The trace format is:

0 3 0x0000000080000108 (0x06f00113) x 2 0x000000000000006f
core_id priv_level pc (instruction) writeback_reg writeback_data

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