[dv] Simplify instructions for how to use Spike with cosim

This depends on Spike version ibex-cosim-v0.2 (which exposes the
various library headers with pkg-config, making configuration much
easier).

ci/ibex-rtl-ci-steps.yml

@@ -67,10 +67,6 @@ steps:
       displayName: Run RISC-V Compliance test for Ibex RV32IMC for ${{ config }}
 
     - bash: |
-        # Setup environment to use cosim with Simple System
-        export IBEX_COSIM_ISS_ROOT=/opt/spike-cosim
-        export LD_LIBRARY_PATH=/opt/spike-cosim/lib:$LD_LIBRARY_PATH
-
         # Build simple system with co-simulation
         fusesoc --cores-root=. run --target=sim --setup --build lowrisc:ibex:ibex_simple_system_cosim $IBEX_CONFIG_OPTS
 

doc/03_reference/cosim.rst

@@ -28,13 +28,12 @@ Setup and Usage
 Clone the `lowRISC fork of Spike <https://github.com/lowRISC/riscv-isa-sim>`_ and check out the ``ibex-cosim-v0.2`` tag.
 Other, later, versions called ``ibex-cosim-v*`` may also work but there's no guarantee of backwards compatibility.
 Follow the Spike build instructions to build and install Spike.
-The build will install multiple header files and libraries, it is recommended a custom install location (using ``--prefix=<path>`` with ``configure``) is used to avoid cluttering system directories.
 The ``--enable-commitlog`` and ``--enable-misaligned`` options must be passed to ``configure``.
+We recommend using a custom install location (using ``--prefix=<path>`` with ``configure``) to avoid cluttering system directories.
+Note that, if you do this, you will also need to add an entry to ``PKG_CONFIG_PATH`` so that ``pkg-config`` can tell us how to build against the installed Spike libraries.
 
-Once built, the ``IBEX_COSIM_ISS_ROOT`` environment variable must be set to the Spike root install directory (as given by ``--prefix=<path>`` to ``configure``) in order to build either the UVM DV environment or Simple System with co-simulation support.
-
-To build/run the UVM DV environment with the co-simulator add the ``COSIM=1`` argument to the make command.
-To build Simple System with the co-simulator build the ``lowrisc:ibex:ibex_simple_system_cosim`` core.
+To build/run the UVM DV environment with the co-simulator, add the ``COSIM=1`` argument to the make command.
+To build Simple System with the co-simulator, build the ``lowrisc:ibex:ibex_simple_system_cosim`` core.
 
 Quick Build and Run Instructions
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -55,9 +54,6 @@ Build and install the co-simulator
   ../configure --enable-commitlog --enable-misaligned --prefix=/opt/spike-cosim
   sudo make -j8 install
 
-  # Setup IBEX_COSIM_ISS_ROOT so build flow can find the co-simulator
-  export IBEX_COSIM_ISS_ROOT=/opt/spike-cosim
-
 Run the UVM DV regression with co-simulation enabled
 
 .. code-block:: bash
@@ -78,9 +74,6 @@ Build and run Simple System with the co-simulation enabled
   # any read of those CSRs results in a mismatch and a failure.
   make -C ./examples/sw/benchmarks/coremark SUPPRESS_PCOUNT_DUMP=1
 
-  # Spike's libsoftfloat.so needs to be accessible so add it to LD_LIBRARY_PATH
-  export LD_LIBRARY_PATH=/opt/spike-cosim/lib:$LD_LIBRARY_PATH
-
   # Run coremark binary with co-simulation checking
   build/lowrisc_ibex_ibex_simple_system_cosim_0/sim-verilator/Vibex_simple_system --meminit=ram,examples/sw/benchmarks/coremark/coremark.elf
 

doc/03_reference/verification.rst

@@ -208,9 +208,6 @@ The entirety of this flow is controlled by the Makefile found at
    # Compile and run RTL simulation
    make TEST=xxx compile,rtl_sim
 
-   # Use a different ISS (default is spike)
-   make ... ISS=ovpsim
-
    # Run a full regression with coverage
    make COV=1
 

dv/uvm/core_ibex/Makefile

@@ -8,16 +8,6 @@ GEN_DIR             := $(realpath ../../../vendor/google_riscv-dv)
 TOOLCHAIN           := ${RISCV_TOOLCHAIN}
 export IBEX_ROOT    := $(realpath ../../../)
 
-ifeq ($(COSIM),1)
-ifndef IBEX_COSIM_ISS_ROOT
-$(error IBEX_COSIM_ISS_ROOT must be set to the root of a suitable spike build if COSIM=1)
-else
-# Spike builds a libsoftfloat.so shared library that the simulator binary needs.
-# Set LD_LIBRARY_PATH so it can be found.
-export LD_LIBRARY_PATH := $(IBEX_COSIM_ISS_ROOT)/lib/:${LD_LIBRARY_PATH}
-endif
-endif
-
 # Explicitly ask for the bash shell
 SHELL                := bash
 

dv/uvm/core_ibex/yaml/rtl_simulation.yaml

@@ -17,7 +17,7 @@
 # As a result, passing -fno-extended-identifiers tells G++ to pretend that
 # everything is ASCII, preventing strange compilation errors.
 - tool: vcs
-  env_var: IBEX_COSIM_ISS_ROOT,IBEX_ROOT
+  env_var: SPIKE_CFLAGS,SPIKE_LDFLAGS,SPIKE_LIBS,IBEX_ROOT
   compile:
     cmd:
       - "vcs -f <core_ibex>/ibex_dv.f  -full64
@@ -46,11 +46,10 @@
     cosim_opts: >
       -f <core_ibex>/ibex_dv_cosim_dpi.f
       +define+INC_IBEX_COSIM
-      -LDFLAGS '-L<IBEX_COSIM_ISS_ROOT>/lib/'
-      -CFLAGS '-I<IBEX_COSIM_ISS_ROOT>/include'
-      -CFLAGS '-I<IBEX_COSIM_ISS_ROOT>/include/softfloat'
+      -LDFLAGS '<SPIKE_LDFLAGS>'
+      -CFLAGS '<SPIKE_CFLAGS>'
       -CFLAGS '-I<IBEX_ROOT>/dv/cosim'
-      -lriscv -lsoftfloat -lfdt -ldl -ldisasm -lstdc++
+      <SPIKE_LIBS> -lstdc++
   sim:
     cmd: >
       env SIM_DIR=<sim_dir>

dv/verilator/simple_system_cosim/ibex_cosim_setup_check.core

@@ -3,7 +3,7 @@ CAPI=2:
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 name: "lowrisc:tool:ibex_cosim_setup_check:0.1"
-description: "Check $IBEX_COSIM_ISS_ROOT is set"
+description: "Check that Spike is installed properly for cosim"
 
 filesets:
   files_ibex_cosim_setup_check: