Fix Verilator warning and ELF-to-HEX build issues on 64-bit Linux

[mdjannatulnayem]

While building and running Clarinet on a 64-bit Linux system, I encountered two issues:

1. Simulator warnings are treated as fatal errors
2. elf_to_hex build fails due to large global/static memory allocations

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Problem 1: Verilator fatal warnings

When running make simulator, some warnings cause the build to fail.

Proposed fix:
Append the flag --Wno-fatal to Verilator:

make simulator VERILATOR_FLAGS+=" --Wno-fatal"

This prevents warnings from stopping the simulation build.

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Problem 2: elf_to_hex fails on 64-bit Linux

The elf_to_hex.c file defines a very large static buffer:

#define MAX_MEM_SIZE ((uint64_t) 0x90000000)
uint8_t mem_buf[MAX_MEM_SIZE];  // ~2.4 GB

On 64-bit Linux, the default PIE executable uses R_X86_64_PC32 relocations, which cannot address such a large global. The linker fails with:

relocation truncated to fit

Proposed fixes:

1. Disable PIE:

gcc -g -no-pie -o elf_to_hex elf_to_hex.c -lelf

2. Use the large memory model for globals > 2 GB:

gcc -g -mcmodel=large -o elf_to_hex elf_to_hex.c -lelf

3. Or combine both:

gcc -g -mcmodel=large -no-pie -o elf_to_hex elf_to_hex.c -lelf

Steps to reproduce manually:

# Build elf_to_hex first
cd Tests/elf_to_hex
make clean
gcc -g -mcmodel=large -no-pie -o elf_to_hex elf_to_hex.c -lelf

# Then build tests in Verilator
cd ../../builds/RV32ACDFIMSU_verilator
make test

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Conclusion:
Applying these fixes allows the project to build successfully on modern 64-bit Linux systems and prevents trivial warnings from breaking the simulation build.