debug/gdbserver.py

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