CEP COSIM: All ISA tests fail when built on Ubuntu 22.04, running with QuestaSim 2023.4 (but pass on RHEL8)

[bchetwynd]

The CEP cosim uses the isaTests as compiled from the ./toolchains/riscv-tools/riscv-tests directory per the instructions in ./sim/cep_cosim/README.md

As an example, looking at the rv64mi-p-csr.dump file when compiled on Ubuntu 22.04: ` rv64mi-p-csr: file format elf64-littleriscv

Disassembly of section .text.init:

0000000080000040 <_start>: 80000040: 04c0006f j 8000008c

0000000080000044 : 80000044: 34202f73 csrr t5,mcause 80000048: 00800f93 li t6,8 8000004c: 03ff0a63 beq t5,t6,80000080 80000050: 00900f93 li t6,9 80000054: 03ff0663 beq t5,t6,80000080 80000058: 00b00f93 li t6,11 8000005c: 03ff0263 beq t5,t6,80000080 80000060: 00000f17 auipc t5,0x0 80000064: 3d8f0f13 addi t5,t5,984 # 80000438 80000068: 000f0463 beqz t5,80000070 <trap_vector+0x2c> 8000006c: 000f0067 jr t5 80000070: 34202f73 csrr t5,mcause 80000074: 000f5463 bgez t5,8000007c 80000078: 0040006f j 8000007c ... `

The same file when compiled on RHEL8: ` rv64mi-p-csr: file format elf64-littleriscv

Disassembly of section .text.init:

0000000080000000 <_start>: 80000000: 04c0006f j 8000004c

0000000080000004 : 80000004: 34202f73 csrr t5,mcause 80000008: 00800f93 li t6,8 8000000c: 03ff0a63 beq t5,t6,80000040 80000010: 00900f93 li t6,9 80000014: 03ff0663 beq t5,t6,80000040 80000018: 00b00f93 li t6,11 8000001c: 03ff0263 beq t5,t6,80000040 80000020: 00000f17 auipc t5,0x0 80000024: 3d8f0f13 addi t5,t5,984 # 800003f8 80000028: 000f0463 beqz t5,80000030 <trap_vector+0x2c> 8000002c: 000f0067 jr t5 80000030: 34202f73 csrr t5,mcause 80000034: 000f5463 bgez t5,8000003c 80000038: 0040006f j 8000003c `

For some reason compiling Ubuntu introduces a 64 (0x40) byte offset in <_start>. This causes the CEP to jump to uninitialized memory at 0x80000000.