Set default entry point from ELF

riscv/sim.cc

@@ -45,8 +45,6 @@ sim_t::sim_t(const char* isa, size_t nprocs, bool halted, reg_t start_pc,
 
   clint.reset(new clint_t(procs));
   bus.add_device(CLINT_BASE, clint.get());
-
-  make_dtb();
 }
 
 sim_t::~sim_t()
@@ -230,6 +228,7 @@ void sim_t::make_dtb()
 {
   const int reset_vec_size = 8;
 
+  start_pc = start_pc == reg_t(-1) ? get_entry_point() : start_pc;
   reg_t pc_delta = start_pc - DEFAULT_RSTVEC;
   reg_t pc_delta_hi = (pc_delta + 0x800U) & ~reg_t(0xfffU);
   reg_t pc_delta_lo = pc_delta - pc_delta_hi;
@@ -325,6 +324,11 @@ char* sim_t::addr_to_mem(reg_t addr) {
 
 // htif
 
+void sim_t::reset()
+{
+  make_dtb();
+}
+
 void sim_t::idle()
 {
   target.switch_to();

riscv/sim.h

@@ -31,7 +31,7 @@ public:
   void set_histogram(bool value);
   void set_procs_debug(bool value);
   void set_gdbserver(gdbserver_t* gdbserver) { this->gdbserver = gdbserver; }
-  const char* get_dts() { return dts.c_str(); }
+  const char* get_dts() { if (dts.empty()) reset(); return dts.c_str(); }
   processor_t* get_core(size_t i) { return procs.at(i); }
 
 private:
@@ -95,7 +95,7 @@ private:
 
   context_t* host;
   context_t target;
-  void reset() { }
+  void reset();
   void idle();
   void read_chunk(addr_t taddr, size_t len, void* dst);
   void write_chunk(addr_t taddr, size_t len, const void* src);

spike_main/spike.cc

@@ -27,7 +27,7 @@ static void help()
   fprintf(stderr, "  -h                    Print this help message\n");
   fprintf(stderr, "  -H                 Start halted, allowing a debugger to connect\n");
   fprintf(stderr, "  --isa=<name>          RISC-V ISA string [default %s]\n", DEFAULT_ISA);
-  fprintf(stderr, "  --pc=<address>        Set the initial program counter [default 0x80000000]\n");
+  fprintf(stderr, "  --pc=<address>        Override ELF entry point\n");
   fprintf(stderr, "  --ic=<S>:<W>:<B>      Instantiate a cache model with S sets,\n");
   fprintf(stderr, "  --dc=<S>:<W>:<B>        W ways, and B-byte blocks (with S and\n");
   fprintf(stderr, "  --l2=<S>:<W>:<B>        B both powers of 2).\n");
@@ -75,7 +75,7 @@ int main(int argc, char** argv)
   bool log = false;
   bool dump_dts = false;
   size_t nprocs = 1;
-  reg_t start_pc = DRAM_BASE;
+  reg_t start_pc = reg_t(-1);
   std::vector<std::pair<reg_t, mem_t*>> mems;
   std::unique_ptr<icache_sim_t> ic;
   std::unique_ptr<dcache_sim_t> dc;