debug/gdbserver.py

   1 #!/usr/bin/env python
   2
   3 import os
   4 import sys
   5 import argparse
   6 import unittest
   7 import tempfile
   8 import time
   9 import random
  10 import binascii
  11
  12 import .testlib
  13
  14
  15 MSTATUS_UIE = 0x00000001
  16 MSTATUS_SIE = 0x00000002
  17 MSTATUS_HIE = 0x00000004
  18 MSTATUS_MIE = 0x00000008
  19 MSTATUS_UPIE = 0x00000010
  20 MSTATUS_SPIE = 0x00000020
  21 MSTATUS_HPIE = 0x00000040
  22 MSTATUS_MPIE = 0x00000080
  23 MSTATUS_SPP = 0x00000100
  24 MSTATUS_HPP = 0x00000600
  25 MSTATUS_MPP = 0x00001800
  26 MSTATUS_FS = 0x00006000
  27 MSTATUS_XS = 0x00018000
  28 MSTATUS_MPRV = 0x00020000
  29 MSTATUS_PUM = 0x00040000
  30 MSTATUS_MXR = 0x00080000
  31 MSTATUS_VM = 0x1F000000
  32 MSTATUS32_SD = 0x80000000
  33 MSTATUS64_SD = 0x8000000000000000
  34
  35 def gdb(
  36         target=None,
  37         port=None,
  38         binary=None
  39         ):
  40
  41     gdb = None
  42     if parsed.gdb:
  43         gdb = testlib.Gdb(parsed.gdb)
  44     else:
  45         gdb = testlib.Gdb()
  46
  47     if binary:
  48         gdb.command("file %s" % binary)
  49     if target:
  50         gdb.command("set arch riscv:rv%d" % target.xlen)
  51         gdb.command("set remotetimeout %d" % target.timeout_sec)
  52     if port:
  53         gdb.command("target extended-remote localhost:%d" % port)
  54
  55     return gdb
  56
  57
  58 def ihex_line(address, record_type, data):
  59     assert len(data) < 128
  60     line = ":%02X%04X%02X" % (len(data), address, record_type)
  61     check = len(data)
  62     check += address % 256
  63     check += address >> 8
  64     check += record_type
  65     for char in data:
  66         value = ord(char)
  67         check += value
  68         line += "%02X" % value
  69     line += "%02X\n" % ((256-check)%256)
  70     return line
  71
  72 def ihex_parse(line):
  73     assert line.startswith(":")
  74     line = line[1:]
  75     data_len = int(line[:2], 16)
  76     address = int(line[2:6], 16)
  77     record_type = int(line[6:8], 16)
  78     data = ""
  79     for i in range(data_len):
  80         data += "%c" % int(line[8+2*i:10+2*i], 16)
  81     return record_type, address, data
  82
  83 def readable_binary_string(s):
  84     return "".join("%02x" % ord(c) for c in s)
  85
  86 class DeleteServer(unittest.TestCase):
  87     def tearDown(self):
  88         del self.server
  89
  90 class SimpleRegisterTest(DeleteServer):
  91     def setUp(self):
  92         self.server = target.server()
  93         self.gdb = gdb(target, self.server.port)
  94
  95         # 0x13 is nop
  96         self.gdb.command("p *((int*) 0x%x)=0x13" % target.ram)
  97         self.gdb.command("p *((int*) 0x%x)=0x13" % (target.ram + 4))
  98         self.gdb.command("p *((int*) 0x%x)=0x13" % (target.ram + 8))
  99         self.gdb.p("$pc=0x%x" % target.ram)
 100
 101     def check_reg(self, name):
 102         a = random.randrange(1<<target.xlen)
 103         b = random.randrange(1<<target.xlen)
 104         self.gdb.p("$%s=0x%x" % (name, a))
 105         self.gdb.stepi()
 106         self.assertEqual(self.gdb.p("$%s" % name), a)
 107         self.gdb.p("$%s=0x%x" % (name, b))
 108         self.gdb.stepi()
 109         self.assertEqual(self.gdb.p("$%s" % name), b)
 110
 111     def test_s0(self):
 112         # S0 is saved/restored in DSCRATCH
 113         self.check_reg("s0")
 114
 115     def test_s1(self):
 116         # S1 is saved/restored in Debug RAM
 117         self.check_reg("s1")
 118
 119     def test_t0(self):
 120         # T0 is not saved/restored at all
 121         self.check_reg("t2")
 122
 123     def test_t2(self):
 124         # T2 is not saved/restored at all
 125         self.check_reg("t2")
 126
 127 class SimpleMemoryTest(DeleteServer):
 128     def setUp(self):
 129         self.server = target.server()
 130         self.gdb = gdb(target, self.server.port)
 131
 132     def access_test(self, size, data_type):
 133         self.assertEqual(self.gdb.p("sizeof(%s)" % data_type),
 134                 size)
 135         a = 0x86753095555aaaa & ((1<<(size*8))-1)
 136         b = 0xdeadbeef12345678 & ((1<<(size*8))-1)
 137         self.gdb.p("*((%s*)0x%x) = 0x%x" % (data_type, target.ram, a))
 138         self.gdb.p("*((%s*)0x%x) = 0x%x" % (data_type, target.ram + size, b))
 139         self.assertEqual(self.gdb.p("*((%s*)0x%x)" % (data_type, target.ram)), a)
 140         self.assertEqual(self.gdb.p("*((%s*)0x%x)" % (data_type, target.ram + size)), b)
 141
 142     def test_8(self):
 143         self.access_test(1, 'char')
 144
 145     def test_16(self):
 146         self.access_test(2, 'short')
 147
 148     def test_32(self):
 149         self.access_test(4, 'int')
 150
 151     def test_64(self):
 152         self.access_test(8, 'long long')
 153
 154     def test_block(self):
 155         length = 1024
 156         line_length = 16
 157         a = tempfile.NamedTemporaryFile(suffix=".ihex")
 158         data = ""
 159         for i in range(length / line_length):
 160             line_data = "".join(["%c" % random.randrange(256) for _ in range(line_length)])
 161             data += line_data
 162             a.write(ihex_line(i * line_length, 0, line_data))
 163         a.flush()
 164
 165         self.gdb.command("restore %s 0x%x" % (a.name, target.ram))
 166         for offset in range(0, length, 19*4) + [length-4]:
 167             value = self.gdb.p("*((int*)0x%x)" % (target.ram + offset))
 168             written = ord(data[offset]) | \
 169                     (ord(data[offset+1]) << 8) | \
 170                     (ord(data[offset+2]) << 16) | \
 171                     (ord(data[offset+3]) << 24)
 172             self.assertEqual(value, written)
 173
 174         b = tempfile.NamedTemporaryFile(suffix=".ihex")
 175         self.gdb.command("dump ihex memory %s 0x%x 0x%x" % (b.name, target.ram,
 176             target.ram + length))
 177         for line in b:
 178             record_type, address, line_data = ihex_parse(line)
 179             if (record_type == 0):
 180                 self.assertEqual(readable_binary_string(line_data),
 181                         readable_binary_string(data[address:address+len(line_data)]))
 182
 183 class InstantHaltTest(DeleteServer):
 184     def setUp(self):
 185         self.server = target.server()
 186         self.gdb = gdb(target, self.server.port)
 187
 188     def test_instant_halt(self):
 189         self.assertEqual(target.reset_vector, self.gdb.p("$pc"))
 190         # mcycle and minstret have no defined reset value.
 191         mstatus = self.gdb.p("$mstatus")
 192         self.assertEqual(mstatus & (MSTATUS_MIE | MSTATUS_MPRV |
 193             MSTATUS_VM), 0)
 194
 195     def test_change_pc(self):
 196         """Change the PC right as we come out of reset."""
 197         # 0x13 is nop
 198         self.gdb.command("p *((int*) 0x%x)=0x13" % target.ram)
 199         self.gdb.command("p *((int*) 0x%x)=0x13" % (target.ram + 4))
 200         self.gdb.command("p *((int*) 0x%x)=0x13" % (target.ram + 8))
 201         self.gdb.p("$pc=0x%x" % target.ram)
 202         self.gdb.stepi()
 203         self.assertEqual((target.ram + 4), self.gdb.p("$pc"))
 204         self.gdb.stepi()
 205         self.assertEqual((target.ram + 8), self.gdb.p("$pc"))
 206
 207 class DebugTest(DeleteServer):
 208     def setUp(self):
 209         # Include malloc so that gdb can make function calls. I suspect this
 210         # malloc will silently blow through the memory set aside for it, so be
 211         # careful.
 212         self.binary = target.compile("programs/debug.c", "programs/checksum.c",
 213                 "programs/tiny-malloc.c", "-DDEFINE_MALLOC", "-DDEFINE_FREE")
 214         self.server = target.server()
 215         self.gdb = gdb(target, self.server.port, self.binary)
 216         self.gdb.load()
 217         self.gdb.b("_exit")
 218
 219     def exit(self, expected_result = 0xc86455d4):
 220         output = self.gdb.c()
 221         self.assertIn("Breakpoint", output)
 222         self.assertIn("_exit", output)
 223         self.assertEqual(self.gdb.p("status"), expected_result)
 224
 225     def test_function_call(self):
 226         self.gdb.b("main:start")
 227         self.gdb.c()
 228         self.assertEqual(self.gdb.p('fib(6)'), 8)
 229         self.assertEqual(self.gdb.p('fib(7)'), 13)
 230         self.exit()
 231
 232     def test_change_string(self):
 233         text = "This little piggy went to the market."
 234         self.gdb.b("main:start")
 235         self.gdb.c()
 236         self.gdb.p('fox = "%s"' % text)
 237         self.exit(0x43b497b8)
 238
 239     def test_turbostep(self):
 240         """Single step a bunch of times."""
 241         self.gdb.b("main:start")
 242         self.gdb.c()
 243         self.gdb.command("p i=0");
 244         last_pc = None
 245         advances = 0
 246         jumps = 0
 247         for _ in range(100):
 248             self.gdb.stepi()
 249             pc = self.gdb.p("$pc")
 250             self.assertNotEqual(last_pc, pc)
 251             if (last_pc and pc > last_pc and pc - last_pc <= 4):
 252                 advances += 1
 253             else:
 254                 jumps += 1
 255             last_pc = pc
 256         # Some basic sanity that we're not running between breakpoints or
 257         # something.
 258         self.assertGreater(jumps, 10)
 259         self.assertGreater(advances, 50)
 260
 261     def test_exit(self):
 262         self.exit()
 263
 264     def test_symbols(self):
 265         self.gdb.b("main")
 266         self.gdb.b("rot13")
 267         output = self.gdb.c()
 268         self.assertIn(", main ", output)
 269         output = self.gdb.c()
 270         self.assertIn(", rot13 ", output)
 271
 272     def test_breakpoint(self):
 273         self.gdb.b("rot13")
 274         # The breakpoint should be hit exactly 2 times.
 275         for i in range(2):
 276             output = self.gdb.c()
 277             self.gdb.p("$pc")
 278             self.assertIn("Breakpoint ", output)
 279             #TODO self.assertIn("rot13 ", output)
 280         self.exit()
 281
 282     def test_hwbp_1(self):
 283         if target.instruction_hardware_breakpoint_count < 1:
 284             return
 285
 286         self.gdb.hbreak("rot13")
 287         # The breakpoint should be hit exactly 2 times.
 288         for i in range(2):
 289             output = self.gdb.c()
 290             self.gdb.p("$pc")
 291             self.assertIn("Breakpoint ", output)
 292             #TODO self.assertIn("rot13 ", output)
 293         self.exit()
 294
 295     def test_hwbp_2(self):
 296         if target.instruction_hardware_breakpoint_count < 2:
 297             return
 298
 299         self.gdb.hbreak("main")
 300         self.gdb.hbreak("rot13")
 301         # We should hit 3 breakpoints.
 302         for i in range(3):
 303             output = self.gdb.c()
 304             self.gdb.p("$pc")
 305             self.assertIn("Breakpoint ", output)
 306             #TODO self.assertIn("rot13 ", output)
 307         self.exit()
 308
 309     def test_too_many_hwbp(self):
 310         for i in range(30):
 311             self.gdb.hbreak("*rot13 + %d" % (i * 4))
 312
 313         output = self.gdb.c()
 314         self.assertIn("Cannot insert hardware breakpoint", output)
 315         # Clean up, otherwise the hardware breakpoints stay set and future
 316         # tests may fail.
 317         self.gdb.command("D")
 318
 319     def test_registers(self):
 320         # Get to a point in the code where some registers have actually been
 321         # used.
 322         self.gdb.b("rot13")
 323         self.gdb.c()
 324         self.gdb.c()
 325         # Try both forms to test gdb.
 326         for cmd in ("info all-registers", "info registers all"):
 327             output = self.gdb.command(cmd)
 328             self.assertNotIn("Could not", output)
 329             for reg in ('zero', 'ra', 'sp', 'gp', 'tp'):
 330                 self.assertIn(reg, output)
 331
 332         #TODO
 333         # mcpuid is one of the few registers that should have the high bit set
 334         # (for rv64).
 335         # Leave this commented out until gdb and spike agree on the encoding of
 336         # mcpuid (which is going to be renamed to misa in any case).
 337         #self.assertRegexpMatches(output, ".*mcpuid *0x80")
 338
 339         #TODO:
 340         # The instret register should always be changing.
 341         #last_instret = None
 342         #for _ in range(5):
 343         #    instret = self.gdb.p("$instret")
 344         #    self.assertNotEqual(instret, last_instret)
 345         #    last_instret = instret
 346         #    self.gdb.stepi()
 347
 348         self.exit()
 349
 350     def test_interrupt(self):
 351         """Sending gdb ^C while the program is running should cause it to halt."""
 352         self.gdb.b("main:start")
 353         self.gdb.c()
 354         self.gdb.p("i=123");
 355         self.gdb.c(wait=False)
 356         time.sleep(0.1)
 357         output = self.gdb.interrupt()
 358         #TODO: assert "main" in output
 359         self.assertGreater(self.gdb.p("j"), 10)
 360         self.gdb.p("i=0");
 361         self.exit()
 362
 363 class StepTest(DeleteServer):
 364     def setUp(self):
 365         self.binary = target.compile("programs/step.S")
 366         self.server = target.server()
 367         self.gdb = gdb(target, self.server.port, self.binary)
 368         self.gdb.load()
 369         self.gdb.b("main")
 370         self.gdb.c()
 371
 372     def test_step(self):
 373         main = self.gdb.p("$pc")
 374         for expected in (4, 8, 0xc, 0x10, 0x18, 0x1c, 0x28, 0x20, 0x2c, 0x2c):
 375             self.gdb.stepi()
 376             pc = self.gdb.p("$pc")
 377             self.assertEqual("%x" % pc, "%x" % (expected + main))
 378
 379 class RegsTest(DeleteServer):
 380     def setUp(self):
 381         self.binary = target.compile("programs/regs.S")
 382         self.server = target.server()
 383         self.gdb = gdb(target, self.server.port, self.binary)
 384         self.gdb.load()
 385         self.gdb.b("main")
 386         self.gdb.b("handle_trap")
 387         self.gdb.c()
 388
 389     def test_write_gprs(self):
 390         regs = [("x%d" % n) for n in range(2, 32)]
 391
 392         self.gdb.p("$pc=write_regs")
 393         for i, r in enumerate(regs):
 394             self.gdb.p("$%s=%d" % (r, (0xdeadbeef<<i)+17))
 395         self.gdb.p("$x1=data")
 396         self.gdb.command("b all_done")
 397         output = self.gdb.c()
 398         self.assertIn("Breakpoint ", output)
 399
 400         # Just to get this data in the log.
 401         self.gdb.command("x/30gx data")
 402         self.gdb.command("info registers")
 403         for n in range(len(regs)):
 404             self.assertEqual(self.gdb.x("data+%d" % (8*n), 'g'),
 405                     ((0xdeadbeef<<n)+17) & ((1<<target.xlen)-1))
 406
 407     def test_write_csrs(self):
 408         # As much a test of gdb as of the simulator.
 409         self.gdb.p("$mscratch=0")
 410         self.gdb.stepi()
 411         self.assertEqual(self.gdb.p("$mscratch"), 0)
 412         self.gdb.p("$mscratch=123")
 413         self.gdb.stepi()
 414         self.assertEqual(self.gdb.p("$mscratch"), 123)
 415
 416         self.gdb.command("p $pc=write_regs")
 417         self.gdb.command("p $a0=data")
 418         self.gdb.command("b all_done")
 419         self.gdb.command("c")
 420
 421         self.assertEqual(123, self.gdb.p("$mscratch"))
 422         self.assertEqual(123, self.gdb.p("$x1"))
 423         self.assertEqual(123, self.gdb.p("$csr832"))
 424
 425 class DownloadTest(DeleteServer):
 426     def setUp(self):
 427         length = min(2**20, target.ram_size - 2048)
 428         download_c = tempfile.NamedTemporaryFile(prefix="download_", suffix=".c")
 429         download_c.write("#include <stdint.h>\n")
 430         download_c.write("unsigned int crc32a(uint8_t *message, unsigned int size);\n")
 431         download_c.write("uint32_t length = %d;\n" % length)
 432         download_c.write("uint8_t d[%d] = {\n" % length)
 433         self.crc = 0
 434         for i in range(length / 16):
 435             download_c.write("  /* 0x%04x */ " % (i * 16));
 436             for _ in range(16):
 437                 value = random.randrange(1<<8)
 438                 download_c.write("%d, " % value)
 439                 self.crc = binascii.crc32("%c" % value, self.crc)
 440             download_c.write("\n");
 441         download_c.write("};\n");
 442         download_c.write("uint8_t *data = &d[0];\n");
 443         download_c.write("uint32_t main() { return crc32a(data, length); }\n")
 444         download_c.flush()
 445
 446         if self.crc < 0:
 447             self.crc += 2**32
 448
 449         self.binary = target.compile(download_c.name, "programs/checksum.c")
 450         self.server = target.server()
 451         self.gdb = gdb(target, self.server.port, self.binary)
 452
 453     def test_download(self):
 454         output = self.gdb.load()
 455         self.gdb.command("b _exit")
 456         self.gdb.c()
 457         self.assertEqual(self.gdb.p("status"), self.crc)
 458
 459 class MprvTest(DeleteServer):
 460     def setUp(self):
 461         self.binary = target.compile("programs/mprv.S")
 462         self.server = target.server()
 463         self.gdb = gdb(target, self.server.port, self.binary)
 464         self.gdb.load()
 465
 466     def test_mprv(self):
 467         """Test that the debugger can access memory when MPRV is set."""
 468         self.gdb.c(wait=False)
 469         time.sleep(0.5)
 470         self.gdb.interrupt()
 471         output = self.gdb.command("p/x *(int*)(((char*)&data)-0x80000000)")
 472         self.assertIn("0xbead", output)
 473
 474 class PrivTest(DeleteServer):
 475     def setUp(self):
 476         self.binary = target.compile("programs/priv.S")
 477         self.server = target.server()
 478         self.gdb = gdb(target, self.server.port, self.binary)
 479         self.gdb.load()
 480
 481         misa = self.gdb.p("$misa")
 482         self.supported = set()
 483         if misa & (1<<20):
 484             self.supported.add(0)
 485         if misa & (1<<18):
 486             self.supported.add(1)
 487         if misa & (1<<7):
 488             self.supported.add(2)
 489         self.supported.add(3)
 490
 491     def test_rw(self):
 492         """Test reading/writing priv."""
 493         for privilege in range(4):
 494             self.gdb.p("$priv=%d" % privilege)
 495             self.gdb.stepi()
 496             actual = self.gdb.p("$priv")
 497             self.assertIn(actual, self.supported)
 498             if privilege in self.supported:
 499                 self.assertEqual(actual, privilege)
 500
 501     def test_change(self):
 502         """Test that the core's privilege level actually changes."""
 503
 504         if 0 not in self.supported:
 505             # TODO: return not applicable
 506             return
 507
 508         self.gdb.b("main")
 509         self.gdb.c()
 510
 511         # Machine mode
 512         self.gdb.p("$priv=3")
 513         main = self.gdb.p("$pc")
 514         self.gdb.stepi()
 515         self.assertEqual("%x" % self.gdb.p("$pc"), "%x" % (main+4))
 516
 517         # User mode
 518         self.gdb.p("$priv=0")
 519         self.gdb.stepi()
 520         # Should have taken an exception, so be nowhere near main.
 521         pc = self.gdb.p("$pc")
 522         self.assertTrue(pc < main or pc > main + 0x100)
 523
 524 class Target(object):
 525     directory = None
 526     timeout_sec = 2
 527
 528     def server(self):
 529         raise NotImplementedError
 530
 531     def compile(self, *sources):
 532         binary_name = "%s_%s-%d" % (
 533                 self.name,
 534                 os.path.basename(os.path.splitext(sources[0])[0]),
 535                 self.xlen)
 536         if parsed.isolate:
 537             self.temporary_binary = tempfile.NamedTemporaryFile(
 538                     prefix=binary_name + "_")
 539             binary_name = self.temporary_binary.name
 540         testlib.compile(sources +
 541                 ("programs/entry.S", "programs/init.c",
 542                     "-I", "../env",
 543                     "-T", "targets/%s/link.lds" % (self.directory or self.name),
 544                     "-nostartfiles",
 545                     "-mcmodel=medany",
 546                     "-o", binary_name),
 547                 xlen=self.xlen)
 548         return binary_name
 549
 550 class SpikeTarget(Target):
 551     directory = "spike"
 552     ram = 0x80010000
 553     ram_size = 5 * 1024 * 1024
 554     instruction_hardware_breakpoint_count = 0
 555     reset_vector = 0x1000
 556
 557 class Spike64Target(SpikeTarget):
 558     name = "spike64"
 559     xlen = 64
 560
 561     def server(self):
 562         return testlib.Spike(parsed.cmd, halted=True)
 563
 564 class Spike32Target(SpikeTarget):
 565     name = "spike32"
 566     xlen = 32
 567
 568     def server(self):
 569         return testlib.Spike(parsed.cmd, halted=True, xlen=32)
 570
 571 class FreedomE300Target(Target):
 572     name = "freedom-e300"
 573     xlen = 32
 574     ram = 0x80000000
 575     ram_size = 16 * 1024
 576     instruction_hardware_breakpoint_count = 2
 577
 578     def server(self):
 579         return testlib.Openocd(cmd=parsed.cmd,
 580                 config="targets/%s/openocd.cfg" % self.name)
 581
 582 class FreedomE300SimTarget(Target):
 583     name = "freedom-e300-sim"
 584     xlen = 32
 585     timeout_sec = 240
 586     ram = 0x80000000
 587     ram_size = 256 * 1024 * 1024
 588     instruction_hardware_breakpoint_count = 2
 589
 590     def server(self):
 591         sim = testlib.VcsSim(simv=parsed.run, debug=False)
 592         openocd = testlib.Openocd(cmd=parsed.cmd,
 593                             config="targets/%s/openocd.cfg" % self.name,
 594                             otherProcess = sim)
 595         time.sleep(20)
 596         return openocd
 597
 598 class FreedomU500Target(Target):
 599     name = "freedom-u500"
 600     xlen = 64
 601     ram = 0x80000000
 602     ram_size = 16 * 1024
 603     instruction_hardware_breakpoint_count = 2
 604
 605     def server(self):
 606         return testlib.Openocd(cmd=parsed.cmd,
 607                 config="targets/%s/openocd.cfg" % self.name)
 608
 609 class FreedomU500SimTarget(Target):
 610     name = "freedom-u500-sim"
 611     xlen = 64
 612     timeout_sec = 240
 613     ram = 0x80000000
 614     ram_size = 256 * 1024 * 1024
 615     instruction_hardware_breakpoint_count = 2
 616
 617     def server(self):
 618         sim = testlib.VcsSim(simv=parsed.run, debug=False)
 619         openocd = testlib.Openocd(cmd=parsed.cmd,
 620                             config="targets/%s/openocd.cfg" % self.name,
 621                             otherProcess = sim)
 622         time.sleep(20)
 623         return openocd
 624
 625 targets = [
 626         Spike32Target,
 627         Spike64Target,
 628         FreedomE300Target,
 629         FreedomU500Target,
 630         FreedomE300SimTarget,
 631         FreedomU500SimTarget]
 632
 633 def main():
 634     parser = argparse.ArgumentParser(
 635             epilog="""
 636             Example command line from the real world:
 637             Run all RegsTest cases against a physical FPGA, with custom openocd command:
 638             ./gdbserver.py --freedom-e-300 --cmd "$HOME/SiFive/openocd/src/openocd -s $HOME/SiFive/openocd/tcl -d" -- -vf RegsTest
 639             """)
 640     group = parser.add_mutually_exclusive_group(required=True)
 641     for t in targets:
 642         group.add_argument("--%s" % t.name, action="store_const", const=t,
 643                 dest="target")
 644     parser.add_argument("--run",
 645                         help="The command to use to start the actual target (e.g. simulation)")
 646     parser.add_argument("--cmd",
 647             help="The command to use to start the debug server.")
 648     parser.add_argument("--gdb",
 649             help="The command to use to start gdb.")
 650
 651     xlen_group = parser.add_mutually_exclusive_group()
 652     xlen_group.add_argument("--32", action="store_const", const=32, dest="xlen",
 653             help="Force the target to be 32-bit.")
 654     xlen_group.add_argument("--64", action="store_const", const=64, dest="xlen",
 655             help="Force the target to be 64-bit.")
 656
 657     parser.add_argument("--isolate", action="store_true",
 658             help="Try to run in such a way that multiple instances can run at "
 659             "the same time. This may make it harder to debug a failure if it "
 660             "does occur.")
 661
 662     parser.add_argument("unittest", nargs="*")
 663     global parsed
 664     parsed = parser.parse_args()
 665
 666     global target
 667     target = parsed.target()
 668
 669     if parsed.xlen:
 670         target.xlen = parsed.xlen
 671
 672     unittest.main(argv=[sys.argv[0]] + parsed.unittest)
 673
 674 # TROUBLESHOOTING TIPS
 675 # If a particular test fails, run just that one test, eg.:
 676 # ./gdbserver.py MprvTest.test_mprv
 677 # Then inspect gdb.log and spike.log to see what happened in more detail.
 678
 679 if __name__ == '__main__':
 680     sys.exit(main())