README.md: update Running User-Space Applications chapter

[JeanRochCoulon]

The Running User-Space Applications chapter need to be updated. As this chapter has been written before the GCC version update, the GCC variables are to be updated: riscv64-unknown-elf to be replaced by riscv-non-elf,...

The gate simulation chapter need also to be updated.

[rajatkmitra]

What about the build ?? The most recent version of riscvpk attampt to run with riscv64-unknown-elf

[rajatkmitra]

Also for running user space applications this does not make any sense -
mkdir build
cd build
../configure --prefix=$RISCV --host=riscv64-unknown-elf
make
make install
if this is assuming the run directoy be cva6/
please expain where the build/ directory needs to be created

[rajatkmitra]

The "Running User-Space Applications" section is completely misleading -

1. It seems like the build/ directory needs to be -cva6/tmp/riscv-pk/build
2. After running ../configure --prefix=$RISCV --host=riscv64-unknown-elf, the Makefile is created, and I coud make, make install
3. Then make verilate fails as there is no verilate target in the Makefile
4. Finally I am not sure what this means - work-ver/Variane_testharness $RISCV/riscv64-unknown-elf/bin/pk hello.elf

Please explain this section in as much details as possible.

[JeanRochCoulon]

As you know open source is a collaboration database, made by inputs from all who would like to contribute. As you seem to know how to run pk, I would encourage you to submit a PR to explain better how to use it.

[JeanRochCoulon]

Related to #1569

[rajatkmitra]

Yes, I reviewed #1569.. I am able to run the smoke and compliance tests. Everything worked nicely (I am using verilator but will try porting the design to Xcelium). My only concern was the notes under "Running User-Space Applications" was not very clear. Perhaps

1. Please explain what directory you need to execute %make verilate in this section
2. What is meant by %work-ver/Variane_testharness, is this a directory ?
   I am clear on the riscv-pk (proxy kernel) operation, just missing directlyies from where these need to be executed from

[JeanRochCoulon]

@valentinThomazic

[valentinThomazic]

@rajatkmitra verilate is a target of the Makefile at the root directory of the repo which means that it should be run from there.
work/ver/Variane_testharness is actually an emulator that will let you run your RISCV-V binary with the proxy kernel.

Please let me know if you manage to run your hello world (or not).