Spike has no output and program execution never ends.

[tak-ka3]

Problem

When I execute spike command, nothing is output.

I wrote this easiest C source code

int main() {
        return 0;
}

, and compiled it with the following command.

$ riscv64-unknown-elf-gcc hello.c -o hello
$ spike pk hello

Then nothing was output. What should I do to execute spike simulation? Even if I executed spike ./riscv64_github/riscv64-unknown-elf/bin/pk hello command, the result was the same.

MY env

compiler

I used rvv-next branch in https://github.com/riscv-collab/riscv-gnu-toolchain and riscv-gcc-rvv-next branch in https://github.com/riscv-collab/riscv-gcc to build. I want to use rvv instructions.

$ riscv64-unknown-elf-gcc -v
Using built-in specs.
COLLECT_GCC=riscv64-unknown-elf-gcc
COLLECT_LTO_WRAPPER=/home/hiraoka/riscv64_github/libexec/gcc/riscv64-unknown-elf/12.2.0/lto-wrapper
Target: riscv64-unknown-elf
Configured with: /home/hiraoka/research/riscv-llvm/riscv-gnu-toolchain/riscv-gcc/configure --target=riscv64-unknown-elf --prefix=/home/hiraoka/riscv64_github --disable-shared --disable-threads --enable-languages=c,c++ --with-pkgversion=geb96155f49d --with-system-zlib --enable-tls --with-newlib --with-sysroot=/home/hiraoka/riscv64_github/riscv64-unknown-elf --with-native-system-header-dir=/include --disable-libmudflap --disable-libssp --disable-libquadmath --disable-libgomp --disable-nls --disable-tm-clone-registry --src=.././riscv-gcc --disable-multilib --with-abi=lp64d --with-arch=rv64gcv --with-tune=rocket --with-isa-spec=2.2 'CFLAGS_FOR_TARGET=-Os   -mcmodel=medlow' 'CXXFLAGS_FOR_TARGET=-Os   -mcmodel=medlow'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 12.2.0 (geb96155f49d)

spike

I used master branch in this repo(https://github.com/riscv-software-src/riscv-isa-sim) to build. I used the command described here(https://github.com/riscv-software-src/riscv-isa-sim#build-steps).

pk

I used master branch in the repo(https://github.com/riscv-software-src/riscv-pk). to build. I built using the following command.

$ cd build
$ ../configure --prefix=/home/hiraoka/riscv64_github --host=riscv64-unknown-elf --with-arch=rv64gcv
$ make 
$ make install

[aswaterman]

No output is the expected behavior here, because the program you’re running produces no output. It’s the same as if you compiled and ran that program on your host machine.

[tak-ka3]

The way I explained my situation was not good. Spike has no output and program execution never ends like an endless loop. To stop the execution I have to execute ctr+c. Also even if I try the following code, there is no output and program never ends.

#include <stdio.h>

int main() {
        printf("Hello, World\n");
        return 0;
}

[tak-ka3]

Like this

[tak-ka3]

Hi, @aswaterman I retried to build RVV simulator env in my other Ubuntu PC. Then I encountered the same error as above after switching to rvv-next branch from master branch in riscv-gnu-toolchain repository(https://github.com/riscv-collab/riscv-gnu-toolchain) and simulating with spike pk hello command. That means before swiching I can simulate RISC-V instructions except for RVV instructions using spike. I wanted to simulate RVV instructions and I used rvv-next branch. If I want to do them, do I not have to use rvv-next branch and are there other ways to simulate RVV instructions using spike?

Thanks,

[aswaterman]

Sorry, I can't help debug this. You'll have to figure it out yourself. All I can say is that Spike support for the V extension is known to be functional. Something in your software environment is presumably not working correctly.

[aswaterman]

Silly question, are you enabling the V extension in Spike by using --isa=rv64gcv?

[tak-ka3]

Even if I execute spike pk hello --isa=rv64gcv, spike doesn't work.

[aswaterman]

Arguments to Spike need to immediately follow spike. In that position, it is an argument to hello. As in, spike --isa=rv64gcv pk hello

[tak-ka3]

Ah, thanks. But even though I execute spike --isa=rv64gcv pk hello, it doesn't work.

[aswaterman]

You're own your own, then. You can try single-stepping through the execution and seeing where things go wrong, but that requires understanding of the internals of pk and the userspace runtime. Sorry I can't help any further.

[tak-ka3]

Thank you for your advice! I want to do know just only the site written about the way to debug pk at the end, if you know.

[aswaterman]

BTW, here is proof that this can work. I used the most recent spike, most recent pk, and gcc 11.2.0.

$ cat test.c
#include <stdio.h>
int main()
{
  unsigned long vlmax;
  asm ("vsetvli %0, x0, e8, m8, ta, ma" : "=r" (vlmax));
  printf("For SEW=8 LMUL=8, VLMAX=%lu\n", vlmax);
  return 0;
}
$ riscv64-unknown-elf-gcc -march=rv64gcv test.c
$ spike --isa=rv64gcv pk a.out
bbl loader
For SEW=8 LMUL=8, VLMAX=128
$ 

[tak-ka3]

Can you include <riscv_vector.h> to use RVV intrinsics without errors?

[aswaterman]

Nope. It's an older version of the compiler. Sorry.

[aswaterman]

Anyway, this pretty clearly isn't a Spike bug, so I'm going to close the issue.