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https://github.com/chipsalliance/Cores-VeeR-EL2

VeeR EL2 Core
https://github.com/chipsalliance/Cores-VeeR-EL2

ahb-lite asic-design axi4 el2 fpga fusesoc open-source-hardware processor risc-v riscv riscv32 rtl verilator western-digital

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VeeR EL2 Core

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README

        

# VeeR EL2 RISC-V Core

This repository contains the VeeR EL2 RISC-V Core design RTL.

## License

By contributing to this project, you agree that your contribution is governed by [Apache-2.0](LICENSE).
Files under the [tools](tools/) directory may be available under a different license. Please review individual files for details.

## Directory Structure

├── configs # Configurations Dir
│   └── snapshots # Where generated configuration files are created
├── design # Design root dir
│   ├── dbg # Debugger
│   ├── dec # Decode, Registers and Exceptions
│   ├── dmi # DMI block
│   ├── exu # EXU (ALU/MUL/DIV)
│   ├── ifu # Fetch & Branch Prediction
│   ├── include
│   ├── lib
│   └── lsu # Load/Store
├── docs
├── tools # Scripts/Makefiles
└── testbench # (Very) simple testbench
   ├── asm # Example assembly files
   ├── hex # Canned demo hex files
   └── tests # Example tests

## Dependencies

- Verilator **(4.106 or later)** must be installed on the system if running with Verilator
- If adding/removing instructions, [`espresso`](https://github.com/chipsalliance/espresso/tree/master) must be installed (used by `tools/coredecode`). Remember to checkout on `3.x` branch.
- RISCV tool chain (based on gcc version 8.3 or higher) must be
installed so that it can be used to prepare RISCV binaries to run.

## Quickstart guide

1. Clone the repository, clone submodules with `git submodule update --init --recursive`
1. Setup `RV_ROOT` to point to the path in your local filesystem
1. Determine your configuration (optional)
1. Run `make` with `tools/Makefile`

## Release Notes for this version

Please see [release notes](release-notes.md) for changes and bug fixes in this version of VeeR.

### Configurations

VeeR can be configured by running the `$RV_ROOT/configs/veer.config` script:

`% $RV_ROOT/configs/veer.config -h` for detailed help options

For example to build with a DCCM of size 64 Kb:

`% $RV_ROOT/configs/veer.config -dccm_size=64`

This will update the **default** snapshot in `./snapshots/default/` with parameters for a 64K DCCM.

Add `-snapshot=dccm64`, for example, if you wish to name your build snapshot `dccm64` and refer to it during the build.

There are 4 predefined target configurations: `default`, `default_ahb`, `typical_pd` and `high_perf` that can be selected via
the `-target=name` option to `veer.config`. **Note:** that the `typical_pd` target is what we base our published PPA numbers. It does not include an ICCM.

**Building an FPGA speed optimized model:**
Use ``-fpga_optimize=1`` option to ``veer.config`` to build a model that removes clock gating logic from flop model so that the FPGA builds can run at higher speeds. **This is now the default option for targets other than ``typical_pd``.**

**Building a Power optimized model (ASIC flows):**
Use ``-fpga_optimize=0`` option to ``veer.config`` to build a model that **enables** clock gating logic into the flop model so that the ASIC flows get a better power footprint. **This is now the default option for target``typical_pd``.**

This script derives the following consistent set of include files:

./snapshots/default
├── common_defines.vh # `defines for testbench or design
├── defines.h # #defines for C/assembly headers
├── el2_param.vh # Design parameters
├── el2_pdef.vh # Parameter structure
├── pd_defines.vh # `defines for physical design
├── perl_configs.pl # Perl %configs hash for scripting
├── pic_map_auto.h # PIC memory map based on configure size
└── whisper.json # JSON file for veer-iss
└── link.ld # default linker control file

### Building a model

While in a work directory:

1. Set the `RV_ROOT` environment variable to the root of the VeeR directory structure.

Example for bash shell: `export RV_ROOT=/path/to/veer`
Example for csh or its derivatives: `setenv RV_ROOT /path/to/veer`

1. Create your specific configuration

*(Skip if default is sufficient)*
*(Name your snapshot to distinguish it from the default. Without an explicit name, it will update/override the __default__ snapshot)*

For example if `mybuild` is the name for the snapshot:

`$RV_ROOT/configs/veer.config [configuration options..] -snapshot=mybuild`

Snapshots are placed in the `./snapshots` directory

1. Run a simple Hello World program (Verilator)

```shell
make -f $RV_ROOT/tools/Makefile
```

This command will build a Verilator model of VeeR EL2 with the AXI bus, and
execute a short sequence of instructions that writes out "HELLO WORLD"
to the bus.

The simulation produces output on the screen like:

```
VerilatorTB: Start of sim

-------------------------
Hello World from VeeR EL2
-------------------------
TEST_PASSED

Finished : minstret = 437, mcycle = 922
See "exec.log" for execution trace with register updates..

```
The simulation generates the following files:

* `console.log` contains what the cpu writes to the console address of 0xd0580000.
* `exec.log` shows instruction trace with GPR updates.
* `trace_port.csv` contains a log of the trace port.

When `debug=1` is provided, a vcd file `sim.vcd` is created and can be browsed by gtkwave or similar waveform viewers.

You can re-execute the simulation using:

```shell
make -f $RV_ROOT/tools/Makefile verilator
```

The simulation run/build command has following generic form:

```shell
make -f $RV_ROOT/tools/Makefile [] [debug=1] [snapshot=mybuild] [target=] [TEST=] [TEST_DIR=]
```

where:

```
- can be 'verilator' (by default) 'irun' - Cadence xrun, 'vcs' - Synopsys VCS, 'vlog' Mentor Questa
'riviera'- Aldec Riviera-PRO. if not provided, 'make' cleans work directory, builds verilator executable and runs a test.
debug=1 - allows VCD generation for verilator and VCS and SHM waves for irun option.
assert=1 - enables assertions in simulation runs (with simulators other than Verilator)
- predefined CPU configurations 'default' ( by default), 'default_ahb', 'typical_pd', 'high_perf'
TEST - allows to run a C (.c) or assembly (.s) test, hello_world is run by default
TEST_DIR - alternative to test source directory testbench/asm or testbench/tests
- run and build executable model of custom CPU configuration, remember to provide 'snapshot' argument
for runs on custom configurations.
CONF_PARAMS - allows to provide -set options to veer.conf script to alter predefined EL2 targets parameters
```

Example:

```shell
make -f $RV_ROOT/tools/Makefile verilator TEST=cmark
```

will build and simulate the `testbench/asm/cmark.c` program with Verilator.

If you want to compile a test only, you can run:

```shell
make -f $RV_ROOT/tools/Makefile program.hex TEST= [TEST_DIR=/path/to/dir]
```

The Makefile uses the `snapshot//link.ld` file, generated by the `veer.conf` script by default to build the test executable.
User can provide test specific linker file in form `.ld` to build the test executable,
in the same directory with the test source.

User also can create a test-specific Makefile in `.makefile`, containing building instructions
how to create the `program.hex` file used by simulation. The private Makefile should be in the same directory
as the test source. See examples in the `testbench/asm` directory.

Another way to alter test building process is to use `.mki` file in test source directory. It may help to select multiple sources
to compile and/or alter compilation swiches. See examples in the `testbench/tests/` directory

*(the `program.hex` file is loaded to instruction and LSU bus memory slaves and optionally to DCCM/ICCM at the beginning of simulation)*.

User can build the `program.hex` file by any other means and then run simulation with the following command:

```shell
make -f $RV_ROOT/tools/Makefile
```

Note: You may need to delete the `program.hex` file from the work directory, when running a new test.

The `$RV_ROOT/testbench/asm` directory contains the following tests ready to simulate:

```
hello_world - default test program to run, prints Hello World message to screen and console.log
hello_world_dccm - the same as above, but takes the string from preloaded DCCM.
hello_world_iccm - the same as hello_world, but loads the test code to ICCM via LSU to DMA bridge and then executes
it from there. Runs on EL2 with AXI4 buses only.
cmark - coremark benchmark running with code and data in external memories
cmark_dccm - the same as above, running data and stack from DCCM (faster)
cmark_iccm - the same as above with preloaded code to ICCM (slower, optimized for size to fit into default ICCM).

dhry - Run dhrystone. (Scale by 1757 to get DMIPS/MHZ)
```

The `$RV_ROOT/testbench/hex` directory contains precompiled hex files of the tests, ready for simulation in case RISC-V SW tools are not installed.

**Note**: The testbench has a simple synthesizable bridge that allows you to load the ICCM via load/store instructions. This is only supported for AXI4 builds.