SConstruct

   1 # -*- mode:python -*-
   2
   3 # Copyright (c) 2013, 2015-2020 ARM Limited
   4 # All rights reserved.
   5 #
   6 # The license below extends only to copyright in the software and shall
   7 # not be construed as granting a license to any other intellectual
   8 # property including but not limited to intellectual property relating
   9 # to a hardware implementation of the functionality of the software
  10 # licensed hereunder.  You may use the software subject to the license
  11 # terms below provided that you ensure that this notice is replicated
  12 # unmodified and in its entirety in all distributions of the software,
  13 # modified or unmodified, in source code or in binary form.
  14 #
  15 # Copyright (c) 2011 Advanced Micro Devices, Inc.
  16 # Copyright (c) 2009 The Hewlett-Packard Development Company
  17 # Copyright (c) 2004-2005 The Regents of The University of Michigan
  18 # All rights reserved.
  19 #
  20 # Redistribution and use in source and binary forms, with or without
  21 # modification, are permitted provided that the following conditions are
  22 # met: redistributions of source code must retain the above copyright
  23 # notice, this list of conditions and the following disclaimer;
  24 # redistributions in binary form must reproduce the above copyright
  25 # notice, this list of conditions and the following disclaimer in the
  26 # documentation and/or other materials provided with the distribution;
  27 # neither the name of the copyright holders nor the names of its
  28 # contributors may be used to endorse or promote products derived from
  29 # this software without specific prior written permission.
  30 #
  31 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  34 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  36 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  37 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  38 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  39 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  40 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  41 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  42
  43 ###################################################
  44 #
  45 # SCons top-level build description (SConstruct) file.
  46 #
  47 # While in this directory ('gem5'), just type 'scons' to build the default
  48 # configuration (see below), or type 'scons build/<CONFIG>/<binary>'
  49 # to build some other configuration (e.g., 'build/X86/gem5.opt' for
  50 # the optimized full-system version).
  51 #
  52 # You can build gem5 in a different directory as long as there is a
  53 # 'build/<CONFIG>' somewhere along the target path.  The build system
  54 # expects that all configs under the same build directory are being
  55 # built for the same host system.
  56 #
  57 # Examples:
  58 #
  59 #   The following two commands are equivalent.  The '-u' option tells
  60 #   scons to search up the directory tree for this SConstruct file.
  61 #   % cd <path-to-src>/gem5 ; scons build/X86/gem5.debug
  62 #   % cd <path-to-src>/gem5/build/X86; scons -u gem5.debug
  63 #
  64 #   The following two commands are equivalent and demonstrate building
  65 #   in a directory outside of the source tree.  The '-C' option tells
  66 #   scons to chdir to the specified directory to find this SConstruct
  67 #   file.
  68 #   % cd <path-to-src>/gem5 ; scons /local/foo/build/X86/gem5.debug
  69 #   % cd /local/foo/build/X86; scons -C <path-to-src>/gem5 gem5.debug
  70 #
  71 # You can use 'scons -H' to print scons options.  If you're in this
  72 # 'gem5' directory (or use -u or -C to tell scons where to find this
  73 # file), you can use 'scons -h' to print all the gem5-specific build
  74 # options as well.
  75 #
  76 ###################################################
  77
  78 from __future__ import print_function
  79
  80 # Global Python includes
  81 import atexit
  82 import itertools
  83 import os
  84 import re
  85 import shutil
  86 import subprocess
  87 import sys
  88
  89 from os import mkdir, environ
  90 from os.path import abspath, basename, dirname, expanduser, normpath
  91 from os.path import exists,  isdir, isfile
  92 from os.path import join as joinpath, split as splitpath
  93 from re import match
  94
  95 # SCons includes
  96 import SCons
  97 import SCons.Node
  98 import SCons.Node.FS
  99
 100 from m5.util import compareVersions, readCommand, readCommandWithReturn
 101
 102 AddOption('--colors', dest='use_colors', action='store_true',
 103           help="Add color to abbreviated scons output")
 104 AddOption('--no-colors', dest='use_colors', action='store_false',
 105           help="Don't add color to abbreviated scons output")
 106 AddOption('--with-cxx-config', action='store_true',
 107           help="Build with support for C++-based configuration")
 108 AddOption('--default',
 109           help='Override which build_opts file to use for defaults')
 110 AddOption('--ignore-style', action='store_true',
 111           help='Disable style checking hooks')
 112 AddOption('--gold-linker', action='store_true', help='Use the gold linker')
 113 AddOption('--no-lto', action='store_true',
 114           help='Disable Link-Time Optimization for fast')
 115 AddOption('--force-lto', action='store_true',
 116           help='Use Link-Time Optimization instead of partial linking' +
 117                ' when the compiler doesn\'t support using them together.')
 118 AddOption('--verbose', action='store_true',
 119           help='Print full tool command lines')
 120 AddOption('--without-python', action='store_true',
 121           help='Build without Python configuration support')
 122 AddOption('--without-tcmalloc', action='store_true',
 123           help='Disable linking against tcmalloc')
 124 AddOption('--with-ubsan', action='store_true',
 125           help='Build with Undefined Behavior Sanitizer if available')
 126 AddOption('--with-asan', action='store_true',
 127           help='Build with Address Sanitizer if available')
 128 AddOption('--with-systemc-tests', action='store_true',
 129           help='Build systemc tests')
 130
 131 from gem5_scons import Transform, error, warning, summarize_warnings
 132
 133 if GetOption('no_lto') and GetOption('force_lto'):
 134     error('--no-lto and --force-lto are mutually exclusive')
 135
 136 ########################################################################
 137 #
 138 # Set up the main build environment.
 139 #
 140 ########################################################################
 141
 142 main = Environment()
 143
 144 from gem5_scons.util import get_termcap
 145 termcap = get_termcap()
 146
 147 main_dict_keys = main.Dictionary().keys()
 148
 149 # Check that we have a C/C++ compiler
 150 if not ('CC' in main_dict_keys and 'CXX' in main_dict_keys):
 151     error("No C++ compiler installed (package g++ on Ubuntu and RedHat)")
 152
 153 ###################################################
 154 #
 155 # Figure out which configurations to set up based on the path(s) of
 156 # the target(s).
 157 #
 158 ###################################################
 159
 160 # Find default configuration & binary.
 161 Default(environ.get('M5_DEFAULT_BINARY', 'build/ARM/gem5.debug'))
 162
 163 # helper function: find last occurrence of element in list
 164 def rfind(l, elt, offs = -1):
 165     for i in range(len(l)+offs, 0, -1):
 166         if l[i] == elt:
 167             return i
 168     raise ValueError("element not found")
 169
 170 # Take a list of paths (or SCons Nodes) and return a list with all
 171 # paths made absolute and ~-expanded.  Paths will be interpreted
 172 # relative to the launch directory unless a different root is provided
 173 def makePathListAbsolute(path_list, root=GetLaunchDir()):
 174     return [abspath(joinpath(root, expanduser(str(p))))
 175             for p in path_list]
 176
 177 # Each target must have 'build' in the interior of the path; the
 178 # directory below this will determine the build parameters.  For
 179 # example, for target 'foo/bar/build/X86/arch/x86/blah.do' we
 180 # recognize that X86 specifies the configuration because it
 181 # follow 'build' in the build path.
 182
 183 # The funky assignment to "[:]" is needed to replace the list contents
 184 # in place rather than reassign the symbol to a new list, which
 185 # doesn't work (obviously!).
 186 BUILD_TARGETS[:] = makePathListAbsolute(BUILD_TARGETS)
 187
 188 # Generate a list of the unique build roots and configs that the
 189 # collected targets reference.
 190 variant_paths = []
 191 build_root = None
 192 for t in BUILD_TARGETS:
 193     path_dirs = t.split('/')
 194     try:
 195         build_top = rfind(path_dirs, 'build', -2)
 196     except:
 197         error("No non-leaf 'build' dir found on target path.", t)
 198     this_build_root = joinpath('/',*path_dirs[:build_top+1])
 199     if not build_root:
 200         build_root = this_build_root
 201     else:
 202         if this_build_root != build_root:
 203             error("build targets not under same build root\n"
 204                   "  %s\n  %s" % (build_root, this_build_root))
 205     variant_path = joinpath('/',*path_dirs[:build_top+2])
 206     if variant_path not in variant_paths:
 207         variant_paths.append(variant_path)
 208
 209 # Make sure build_root exists (might not if this is the first build there)
 210 if not isdir(build_root):
 211     mkdir(build_root)
 212 main['BUILDROOT'] = build_root
 213
 214 Export('main')
 215
 216 main.SConsignFile(joinpath(build_root, "sconsign"))
 217
 218 # Default duplicate option is to use hard links, but this messes up
 219 # when you use emacs to edit a file in the target dir, as emacs moves
 220 # file to file~ then copies to file, breaking the link.  Symbolic
 221 # (soft) links work better.
 222 main.SetOption('duplicate', 'soft-copy')
 223
 224 #
 225 # Set up global sticky variables... these are common to an entire build
 226 # tree (not specific to a particular build like X86)
 227 #
 228
 229 global_vars_file = joinpath(build_root, 'variables.global')
 230
 231 global_vars = Variables(global_vars_file, args=ARGUMENTS)
 232
 233 global_vars.AddVariables(
 234     ('CC', 'C compiler', environ.get('CC', main['CC'])),
 235     ('CXX', 'C++ compiler', environ.get('CXX', main['CXX'])),
 236     ('CCFLAGS_EXTRA', 'Extra C and C++ compiler flags', ''),
 237     ('LDFLAGS_EXTRA', 'Extra linker flags', ''),
 238     ('MARSHAL_CCFLAGS_EXTRA', 'Extra C and C++ marshal compiler flags', ''),
 239     ('MARSHAL_LDFLAGS_EXTRA', 'Extra marshal linker flags', ''),
 240     ('PYTHON_CONFIG', 'Python config binary to use',
 241      [ 'python3-config', 'python-config']
 242     ),
 243     ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
 244     ('BATCH', 'Use batch pool for build and tests', False),
 245     ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
 246     ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
 247     ('EXTRAS', 'Add extra directories to the compilation', '')
 248     )
 249
 250 # Update main environment with values from ARGUMENTS & global_vars_file
 251 global_vars.Update(main)
 252 Help('''
 253 Global build variables:
 254 {help}
 255 '''.format(help=global_vars.GenerateHelpText(main)), append=True)
 256
 257 # Save sticky variable settings back to current variables file
 258 global_vars.Save(global_vars_file, main)
 259
 260 # Parse EXTRAS variable to build list of all directories where we're
 261 # look for sources etc.  This list is exported as extras_dir_list.
 262 base_dir = main.srcdir.abspath
 263 if main['EXTRAS']:
 264     extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
 265 else:
 266     extras_dir_list = []
 267
 268 Export('base_dir')
 269 Export('extras_dir_list')
 270
 271 # the ext directory should be on the #includes path
 272 main.Append(CPPPATH=[Dir('ext')])
 273
 274 # Add shared top-level headers
 275 main.Prepend(CPPPATH=Dir('include'))
 276
 277 if GetOption('verbose'):
 278     def MakeAction(action, string, *args, **kwargs):
 279         return Action(action, *args, **kwargs)
 280 else:
 281     MakeAction = Action
 282     main['CCCOMSTR']        = Transform("CC")
 283     main['CXXCOMSTR']       = Transform("CXX")
 284     main['ASCOMSTR']        = Transform("AS")
 285     main['ARCOMSTR']        = Transform("AR", 0)
 286     main['LINKCOMSTR']      = Transform("LINK", 0)
 287     main['SHLINKCOMSTR']    = Transform("SHLINK", 0)
 288     main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
 289     main['M4COMSTR']        = Transform("M4")
 290     main['SHCCCOMSTR']      = Transform("SHCC")
 291     main['SHCXXCOMSTR']     = Transform("SHCXX")
 292 Export('MakeAction')
 293
 294 # Initialize the Link-Time Optimization (LTO) flags
 295 main['LTO_CCFLAGS'] = []
 296 main['LTO_LDFLAGS'] = []
 297
 298 # According to the readme, tcmalloc works best if the compiler doesn't
 299 # assume that we're using the builtin malloc and friends. These flags
 300 # are compiler-specific, so we need to set them after we detect which
 301 # compiler we're using.
 302 main['TCMALLOC_CCFLAGS'] = []
 303
 304 CXX_version = readCommand([main['CXX'],'--version'], exception=False)
 305 CXX_V = readCommand([main['CXX'],'-V'], exception=False)
 306
 307 main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
 308 main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
 309 if main['GCC'] + main['CLANG'] > 1:
 310     error('Two compilers enabled at once?')
 311
 312 # Set up default C++ compiler flags
 313 if main['GCC'] or main['CLANG']:
 314     # As gcc and clang share many flags, do the common parts here
 315     main.Append(CCFLAGS=['-pipe'])
 316     main.Append(CCFLAGS=['-fno-strict-aliasing'])
 317     # Enable -Wall and -Wextra and then disable the few warnings that
 318     # we consistently violate
 319     main.Append(CCFLAGS=['-Wall', '-Wundef', '-Wextra',
 320                          '-Wno-sign-compare', '-Wno-unused-parameter'])
 321     # We always compile using C++14
 322     main.Append(CXXFLAGS=['-std=c++14'])
 323     if sys.platform.startswith('freebsd'):
 324         main.Append(CCFLAGS=['-I/usr/local/include'])
 325         main.Append(CXXFLAGS=['-I/usr/local/include'])
 326
 327     # On Mac OS X/Darwin the default linker doesn't support the
 328     # option --as-needed
 329     if sys.platform != "darwin":
 330         main.Append(LINKFLAGS='-Wl,--as-needed')
 331     main['FILTER_PSHLINKFLAGS'] = lambda x: str(x).replace(' -shared', '')
 332     main['PSHLINKFLAGS'] = main.subst('${FILTER_PSHLINKFLAGS(SHLINKFLAGS)}')
 333     if GetOption('gold_linker'):
 334         main.Append(LINKFLAGS='-fuse-ld=gold')
 335     main['PLINKFLAGS'] = main.get('LINKFLAGS')
 336     shared_partial_flags = ['-r', '-nostdlib']
 337     main.Append(PSHLINKFLAGS=shared_partial_flags)
 338     main.Append(PLINKFLAGS=shared_partial_flags)
 339
 340     # Treat warnings as errors but white list some warnings that we
 341     # want to allow (e.g., deprecation warnings).
 342     main.Append(CCFLAGS=['-Werror',
 343                          '-Wno-error=deprecated-declarations',
 344                          '-Wno-error=deprecated',
 345                         ])
 346 else:
 347     error('\n'.join((
 348           "Don't know what compiler options to use for your compiler.",
 349           "compiler: " + main['CXX'],
 350           "version: " + CXX_version.replace('\n', '<nl>') if
 351                 CXX_version else 'COMMAND NOT FOUND!',
 352           "If you're trying to use a compiler other than GCC",
 353           "or clang, there appears to be something wrong with your",
 354           "environment.",
 355           "",
 356           "If you are trying to use a compiler other than those listed",
 357           "above you will need to ease fix SConstruct and ",
 358           "src/SConscript to support that compiler.")))
 359
 360 if main['GCC']:
 361     gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
 362     if compareVersions(gcc_version, "5") < 0:
 363         error('gcc version 5 or newer required.\n'
 364               'Installed version:', gcc_version)
 365         Exit(1)
 366
 367     main['GCC_VERSION'] = gcc_version
 368
 369     # Incremental linking with LTO is currently broken in gcc versions
 370     # 4.9 and above. A version where everything works completely hasn't
 371     # yet been identified.
 372     #
 373     # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548
 374     main['BROKEN_INCREMENTAL_LTO'] = True
 375
 376     if compareVersions(gcc_version, '6.0') >= 0:
 377         # gcc versions 6.0 and greater accept an -flinker-output flag which
 378         # selects what type of output the linker should generate. This is
 379         # necessary for incremental lto to work, but is also broken in
 380         # current versions of gcc. It may not be necessary in future
 381         # versions. We add it here since it might be, and as a reminder that
 382         # it exists. It's excluded if lto is being forced.
 383         #
 384         # https://gcc.gnu.org/gcc-6/changes.html
 385         # https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03161.html
 386         # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866
 387         if not GetOption('force_lto'):
 388             main.Append(PSHLINKFLAGS='-flinker-output=rel')
 389             main.Append(PLINKFLAGS='-flinker-output=rel')
 390
 391     disable_lto = GetOption('no_lto')
 392     if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \
 393             not GetOption('force_lto'):
 394         warning('Your compiler doesn\'t support incremental linking and lto '
 395                 'at the same time, so lto is being disabled. To force lto on '
 396                 'anyway, use the --force-lto option. That will disable '
 397                 'partial linking.')
 398         disable_lto = True
 399
 400     # Add the appropriate Link-Time Optimization (LTO) flags
 401     # unless LTO is explicitly turned off. Note that these flags
 402     # are only used by the fast target.
 403     if not disable_lto:
 404         # Pass the LTO flag when compiling to produce GIMPLE
 405         # output, we merely create the flags here and only append
 406         # them later
 407         main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 408
 409         # Use the same amount of jobs for LTO as we are running
 410         # scons with
 411         main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 412
 413     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
 414                                   '-fno-builtin-realloc', '-fno-builtin-free'])
 415
 416 elif main['CLANG']:
 417     clang_version_re = re.compile(".* version (\d+\.\d+)")
 418     clang_version_match = clang_version_re.search(CXX_version)
 419     if (clang_version_match):
 420         clang_version = clang_version_match.groups()[0]
 421         if compareVersions(clang_version, "3.9") < 0:
 422             error('clang version 3.9 or newer required.\n'
 423                   'Installed version:', clang_version)
 424     else:
 425         error('Unable to determine clang version.')
 426
 427     # clang has a few additional warnings that we disable, extraneous
 428     # parantheses are allowed due to Ruby's printing of the AST,
 429     # finally self assignments are allowed as the generated CPU code
 430     # is relying on this
 431     main.Append(CCFLAGS=['-Wno-parentheses',
 432                          '-Wno-self-assign',
 433                          # Some versions of libstdc++ (4.8?) seem to
 434                          # use struct hash and class hash
 435                          # interchangeably.
 436                          '-Wno-mismatched-tags',
 437                          ])
 438     if sys.platform != "darwin" and \
 439        compareVersions(clang_version, "10.0") >= 0:
 440         main.Append(CCFLAGS=['-Wno-c99-designator'])
 441
 442     if compareVersions(clang_version, "8.0") >= 0:
 443         main.Append(CCFLAGS=['-Wno-defaulted-function-deleted'])
 444
 445     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
 446
 447     # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
 448     # opposed to libstdc++, as the later is dated.
 449     if sys.platform == "darwin":
 450         main.Append(CXXFLAGS=['-stdlib=libc++'])
 451         main.Append(LIBS=['c++'])
 452
 453     # On FreeBSD we need libthr.
 454     if sys.platform.startswith('freebsd'):
 455         main.Append(LIBS=['thr'])
 456
 457 # Add sanitizers flags
 458 sanitizers=[]
 459 if GetOption('with_ubsan'):
 460     sanitizers.append('undefined')
 461 if GetOption('with_asan'):
 462     # Available for gcc >= 5 or llvm >= 3.1 both a requirement
 463     # by the build system
 464     sanitizers.append('address')
 465     suppressions_file = Dir('util').File('lsan-suppressions').get_abspath()
 466     suppressions_opt = 'suppressions=%s' % suppressions_file
 467     main['ENV']['LSAN_OPTIONS'] = ':'.join([suppressions_opt,
 468                                             'print_suppressions=0'])
 469     print()
 470     warning('To suppress false positive leaks, set the LSAN_OPTIONS '
 471             'environment variable to "%s" when running gem5' %
 472             suppressions_opt)
 473     warning('LSAN_OPTIONS=suppressions=%s' % suppressions_opt)
 474     print()
 475 if sanitizers:
 476     sanitizers = ','.join(sanitizers)
 477     if main['GCC'] or main['CLANG']:
 478         main.Append(CCFLAGS=['-fsanitize=%s' % sanitizers,
 479                              '-fno-omit-frame-pointer'],
 480                     LINKFLAGS='-fsanitize=%s' % sanitizers)
 481     else:
 482         warning("Don't know how to enable %s sanitizer(s) for your "
 483                 "compiler." % sanitizers)
 484
 485 # Set up common yacc/bison flags (needed for Ruby)
 486 main['YACCFLAGS'] = '-d'
 487 main['YACCHXXFILESUFFIX'] = '.hh'
 488
 489 # Do this after we save setting back, or else we'll tack on an
 490 # extra 'qdo' every time we run scons.
 491 if main['BATCH']:
 492     main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
 493     main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
 494     main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
 495     main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
 496     main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
 497
 498 if sys.platform == 'cygwin':
 499     # cygwin has some header file issues...
 500     main.Append(CCFLAGS=["-Wno-uninitialized"])
 501
 502
 503 have_pkg_config = readCommand(['pkg-config', '--version'], exception='')
 504
 505 # Check for the protobuf compiler
 506 try:
 507     main['HAVE_PROTOC'] = True
 508     protoc_version = readCommand([main['PROTOC'], '--version']).split()
 509
 510     # First two words should be "libprotoc x.y.z"
 511     if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
 512         warning('Protocol buffer compiler (protoc) not found.\n'
 513                 'Please install protobuf-compiler for tracing support.')
 514         main['HAVE_PROTOC'] = False
 515     else:
 516         # Based on the availability of the compress stream wrappers,
 517         # require 2.1.0
 518         min_protoc_version = '2.1.0'
 519         if compareVersions(protoc_version[1], min_protoc_version) < 0:
 520             warning('protoc version', min_protoc_version,
 521                     'or newer required.\n'
 522                     'Installed version:', protoc_version[1])
 523             main['HAVE_PROTOC'] = False
 524         else:
 525             # Attempt to determine the appropriate include path and
 526             # library path using pkg-config, that means we also need to
 527             # check for pkg-config. Note that it is possible to use
 528             # protobuf without the involvement of pkg-config. Later on we
 529             # check go a library config check and at that point the test
 530             # will fail if libprotobuf cannot be found.
 531             if have_pkg_config:
 532                 try:
 533                     # Attempt to establish what linking flags to add for
 534                     # protobuf
 535                     # using pkg-config
 536                     main.ParseConfig(
 537                             'pkg-config --cflags --libs-only-L protobuf')
 538                 except:
 539                     warning('pkg-config could not get protobuf flags.')
 540 except Exception as e:
 541     warning('While checking protoc version:', str(e))
 542     main['HAVE_PROTOC'] = False
 543
 544 # Check for 'timeout' from GNU coreutils. If present, regressions will
 545 # be run with a time limit. We require version 8.13 since we rely on
 546 # support for the '--foreground' option.
 547 if sys.platform.startswith('freebsd'):
 548     timeout_lines = readCommand(['gtimeout', '--version'],
 549                                 exception='').splitlines()
 550 else:
 551     timeout_lines = readCommand(['timeout', '--version'],
 552                                 exception='').splitlines()
 553 # Get the first line and tokenize it
 554 timeout_version = timeout_lines[0].split() if timeout_lines else []
 555 main['TIMEOUT'] =  timeout_version and \
 556     compareVersions(timeout_version[-1], '8.13') >= 0
 557
 558 # Add a custom Check function to test for structure members.
 559 def CheckMember(context, include, decl, member, include_quotes="<>"):
 560     context.Message("Checking for member %s in %s..." %
 561                     (member, decl))
 562     text = """
 563 #include %(header)s
 564 int main(){
 565   %(decl)s test;
 566   (void)test.%(member)s;
 567   return 0;
 568 };
 569 """ % { "header" : include_quotes[0] + include + include_quotes[1],
 570         "decl" : decl,
 571         "member" : member,
 572         }
 573
 574     ret = context.TryCompile(text, extension=".cc")
 575     context.Result(ret)
 576     return ret
 577
 578 def CheckPythonLib(context):
 579     context.Message('Checking Python version... ')
 580     ret = context.TryRun(r"""
 581 #include <pybind11/embed.h>
 582
 583 int
 584 main(int argc, char **argv) {
 585     pybind11::scoped_interpreter guard{};
 586     pybind11::exec(
 587         "import sys\n"
 588         "vi = sys.version_info\n"
 589         "sys.stdout.write('%i.%i.%i' % (vi.major, vi.minor, vi.micro));\n");
 590     return 0;
 591 }
 592     """, extension=".cc")
 593     context.Result(ret[1] if ret[0] == 1 else 0)
 594     if ret[0] == 0:
 595         return None
 596     else:
 597         return tuple(map(int, ret[1].split(".")))
 598
 599 # Platform-specific configuration.  Note again that we assume that all
 600 # builds under a given build root run on the same host platform.
 601 conf = Configure(main,
 602                  conf_dir = joinpath(build_root, '.scons_config'),
 603                  log_file = joinpath(build_root, 'scons_config.log'),
 604                  custom_tests = {
 605         'CheckMember' : CheckMember,
 606         'CheckPythonLib' : CheckPythonLib,
 607         })
 608
 609 # Check if we should compile a 64 bit binary on Mac OS X/Darwin
 610 try:
 611     import platform
 612     uname = platform.uname()
 613     if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
 614         if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
 615             main.Append(CCFLAGS=['-arch', 'x86_64'])
 616             main.Append(CFLAGS=['-arch', 'x86_64'])
 617             main.Append(LINKFLAGS=['-arch', 'x86_64'])
 618             main.Append(ASFLAGS=['-arch', 'x86_64'])
 619 except:
 620     pass
 621
 622 # Recent versions of scons substitute a "Null" object for Configure()
 623 # when configuration isn't necessary, e.g., if the "--help" option is
 624 # present.  Unfortuantely this Null object always returns false,
 625 # breaking all our configuration checks.  We replace it with our own
 626 # more optimistic null object that returns True instead.
 627 if not conf:
 628     def NullCheck(*args, **kwargs):
 629         return True
 630
 631     class NullConf:
 632         def __init__(self, env):
 633             self.env = env
 634         def Finish(self):
 635             return self.env
 636         def __getattr__(self, mname):
 637             return NullCheck
 638
 639     conf = NullConf(main)
 640
 641 # Cache build files in the supplied directory.
 642 if main['M5_BUILD_CACHE']:
 643     print('Using build cache located at', main['M5_BUILD_CACHE'])
 644     CacheDir(main['M5_BUILD_CACHE'])
 645
 646 main['USE_PYTHON'] = not GetOption('without_python')
 647 if main['USE_PYTHON']:
 648     # Find Python include and library directories for embedding the
 649     # interpreter. We rely on python-config to resolve the appropriate
 650     # includes and linker flags. ParseConfig does not seem to understand
 651     # the more exotic linker flags such as -Xlinker and -export-dynamic so
 652     # we add them explicitly below. If you want to link in an alternate
 653     # version of python, see above for instructions on how to invoke
 654     # scons with the appropriate PATH set.
 655
 656     python_config = main.Detect(main['PYTHON_CONFIG'])
 657     if python_config is None:
 658         error("Can't find a suitable python-config, tried %s" % \
 659               main['PYTHON_CONFIG'])
 660
 661     print("Info: Using Python config: %s" % (python_config, ))
 662
 663     py_includes = readCommand([python_config, '--includes'],
 664                               exception='').split()
 665     py_includes = list(filter(
 666         lambda s: match(r'.*\/include\/.*',s), py_includes))
 667     # Strip the -I from the include folders before adding them to the
 668     # CPPPATH
 669     py_includes = list(map(
 670         lambda s: s[2:] if s.startswith('-I') else s, py_includes))
 671     main.Append(CPPPATH=py_includes)
 672
 673     # Read the linker flags and split them into libraries and other link
 674     # flags. The libraries are added later through the call the CheckLib.
 675     # Note: starting in Python 3.8 the --embed flag is required to get the
 676     # -lpython3.8 linker flag
 677     retcode, cmd_stdout = readCommandWithReturn(
 678         [python_config, '--ldflags', '--embed'], exception='')
 679     if retcode != 0:
 680         # If --embed isn't detected then we're running python <3.8
 681         retcode, cmd_stdout = readCommandWithReturn(
 682             [python_config, '--ldflags'], exception='')
 683
 684     # Checking retcode again
 685     if retcode != 0:
 686         error("Failing on python-config --ldflags command")
 687
 688     py_ld_flags = cmd_stdout.split()
 689
 690     py_libs = []
 691     for lib in py_ld_flags:
 692          if not lib.startswith('-l'):
 693              main.Append(LINKFLAGS=[lib])
 694          else:
 695              lib = lib[2:]
 696              if lib not in py_libs:
 697                  py_libs.append(lib)
 698
 699     # verify that this stuff works
 700     if not conf.CheckHeader('Python.h', '<>'):
 701         error("Check failed for Python.h header in",
 702                 ' '.join(py_includes), "\n"
 703               "Two possible reasons:\n"
 704               "1. Python headers are not installed (You can install the "
 705               "package python-dev on Ubuntu and RedHat)\n"
 706               "2. SCons is using a wrong C compiler. This can happen if "
 707               "CC has the wrong value.\n"
 708               "CC = %s" % main['CC'])
 709
 710     for lib in py_libs:
 711         if not conf.CheckLib(lib):
 712             error("Can't find library %s required by python." % lib)
 713
 714 main.Prepend(CPPPATH=Dir('ext/pybind11/include/'))
 715 # Bare minimum environment that only includes python
 716 marshal_env = main.Clone()
 717 marshal_env.Append(CCFLAGS='$MARSHAL_CCFLAGS_EXTRA')
 718 marshal_env.Append(LINKFLAGS='$MARSHAL_LDFLAGS_EXTRA')
 719 py_version = conf.CheckPythonLib()
 720 if not py_version:
 721     error("Can't find a working Python installation")
 722
 723 # Found a working Python installation. Check if it meets minimum
 724 # requirements.
 725 if py_version[0] < 3 or \
 726    (py_version[0] == 3 and py_version[1] < 6):
 727     error('Python version too old. Version 3.6 or newer is required.')
 728 elif py_version[0] > 3:
 729     warning('Python version too new. Python 3 expected.')
 730
 731 # On Solaris you need to use libsocket for socket ops
 732 if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
 733    if not conf.CheckLibWithHeader('socket', 'sys/socket.h',
 734                                   'C++', 'accept(0,0,0);'):
 735        error("Can't find library with socket calls (e.g. accept()).")
 736
 737 # Check for zlib.  If the check passes, libz will be automatically
 738 # added to the LIBS environment variable.
 739 if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
 740     error('Did not find needed zlib compression library '
 741           'and/or zlib.h header file.\n'
 742           'Please install zlib and try again.')
 743
 744 # If we have the protobuf compiler, also make sure we have the
 745 # development libraries. If the check passes, libprotobuf will be
 746 # automatically added to the LIBS environment variable. After
 747 # this, we can use the HAVE_PROTOBUF flag to determine if we have
 748 # got both protoc and libprotobuf available.
 749 main['HAVE_PROTOBUF'] = main['HAVE_PROTOC'] and \
 750     conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
 751                             'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
 752
 753 # Valgrind gets much less confused if you tell it when you're using
 754 # alternative stacks.
 755 main['HAVE_VALGRIND'] = conf.CheckCHeader('valgrind/valgrind.h')
 756
 757 # If we have the compiler but not the library, print another warning.
 758 if main['HAVE_PROTOC'] and not main['HAVE_PROTOBUF']:
 759     warning('Did not find protocol buffer library and/or headers.\n'
 760             'Please install libprotobuf-dev for tracing support.')
 761
 762 # Check for librt.
 763 have_posix_clock = \
 764     conf.CheckLibWithHeader(None, 'time.h', 'C',
 765                             'clock_nanosleep(0,0,NULL,NULL);') or \
 766     conf.CheckLibWithHeader('rt', 'time.h', 'C',
 767                             'clock_nanosleep(0,0,NULL,NULL);')
 768
 769 have_posix_timers = \
 770     conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
 771                             'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
 772
 773 if not GetOption('without_tcmalloc'):
 774     if conf.CheckLib('tcmalloc'):
 775         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 776     elif conf.CheckLib('tcmalloc_minimal'):
 777         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 778     else:
 779         warning("You can get a 12% performance improvement by "
 780                 "installing tcmalloc (libgoogle-perftools-dev package "
 781                 "on Ubuntu or RedHat).")
 782
 783
 784 # Detect back trace implementations. The last implementation in the
 785 # list will be used by default.
 786 backtrace_impls = [ "none" ]
 787
 788 backtrace_checker = 'char temp;' + \
 789     ' backtrace_symbols_fd((void*)&temp, 0, 0);'
 790 if conf.CheckLibWithHeader(None, 'execinfo.h', 'C', backtrace_checker):
 791     backtrace_impls.append("glibc")
 792 elif conf.CheckLibWithHeader('execinfo', 'execinfo.h', 'C',
 793                              backtrace_checker):
 794     # NetBSD and FreeBSD need libexecinfo.
 795     backtrace_impls.append("glibc")
 796     main.Append(LIBS=['execinfo'])
 797
 798 if backtrace_impls[-1] == "none":
 799     default_backtrace_impl = "none"
 800     warning("No suitable back trace implementation found.")
 801
 802 if not have_posix_clock:
 803     warning("Can't find library for POSIX clocks.")
 804
 805 # Check for <fenv.h> (C99 FP environment control)
 806 have_fenv = conf.CheckHeader('fenv.h', '<>')
 807 if not have_fenv:
 808     warning("Header file <fenv.h> not found.\n"
 809             "This host has no IEEE FP rounding mode control.")
 810
 811 # Check for <png.h> (libpng library needed if wanting to dump
 812 # frame buffer image in png format)
 813 have_png = conf.CheckHeader('png.h', '<>')
 814 if not have_png:
 815     warning("Header file <png.h> not found.\n"
 816             "This host has no libpng library.\n"
 817             "Disabling support for PNG framebuffers.")
 818
 819 # Check if we should enable KVM-based hardware virtualization. The API
 820 # we rely on exists since version 2.6.36 of the kernel, but somehow
 821 # the KVM_API_VERSION does not reflect the change. We test for one of
 822 # the types as a fall back.
 823 have_kvm = conf.CheckHeader('linux/kvm.h', '<>')
 824 if not have_kvm:
 825     print("Info: Compatible header file <linux/kvm.h> not found, "
 826           "disabling KVM support.")
 827
 828 # Check if the TUN/TAP driver is available.
 829 have_tuntap = conf.CheckHeader('linux/if_tun.h', '<>')
 830 if not have_tuntap:
 831     print("Info: Compatible header file <linux/if_tun.h> not found.")
 832
 833 # x86 needs support for xsave. We test for the structure here since we
 834 # won't be able to run new tests by the time we know which ISA we're
 835 # targeting.
 836 have_kvm_xsave = conf.CheckTypeSize('struct kvm_xsave',
 837                                     '#include <linux/kvm.h>') != 0
 838
 839 # Check if the requested target ISA is compatible with the host
 840 def is_isa_kvm_compatible(isa):
 841     try:
 842         import platform
 843         host_isa = platform.machine()
 844     except:
 845         warning("Failed to determine host ISA.")
 846         return False
 847
 848     if not have_posix_timers:
 849         warning("Can not enable KVM, host seems to lack support "
 850                 "for POSIX timers")
 851         return False
 852
 853     if isa == "arm":
 854         return host_isa in ( "armv7l", "aarch64" )
 855     elif isa == "x86":
 856         if host_isa != "x86_64":
 857             return False
 858
 859         if not have_kvm_xsave:
 860             warning("KVM on x86 requires xsave support in kernel headers.")
 861             return False
 862
 863         return True
 864     else:
 865         return False
 866
 867
 868 # Check if the exclude_host attribute is available. We want this to
 869 # get accurate instruction counts in KVM.
 870 main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
 871     'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
 872
 873 def check_hdf5():
 874     return \
 875         conf.CheckLibWithHeader('hdf5', 'hdf5.h', 'C',
 876                                 'H5Fcreate("", 0, 0, 0);') and \
 877         conf.CheckLibWithHeader('hdf5_cpp', 'H5Cpp.h', 'C++',
 878                                 'H5::H5File("", 0);')
 879
 880 def check_hdf5_pkg(name):
 881     print("Checking for %s using pkg-config..." % name, end="")
 882     if not have_pkg_config:
 883         print(" pkg-config not found")
 884         return False
 885
 886     try:
 887         main.ParseConfig('pkg-config --cflags-only-I --libs-only-L %s' % name)
 888         print(" yes")
 889         return True
 890     except:
 891         print(" no")
 892         return False
 893
 894 # Check if there is a pkg-config configuration for hdf5. If we find
 895 # it, setup the environment to enable linking and header inclusion. We
 896 # don't actually try to include any headers or link with hdf5 at this
 897 # stage.
 898 if not check_hdf5_pkg('hdf5-serial'):
 899     check_hdf5_pkg('hdf5')
 900
 901 # Check if the HDF5 libraries can be found. This check respects the
 902 # include path and library path provided by pkg-config. We perform
 903 # this check even if there isn't a pkg-config configuration for hdf5
 904 # since some installations don't use pkg-config.
 905 have_hdf5 = check_hdf5()
 906 if not have_hdf5:
 907     print("Warning: Couldn't find any HDF5 C++ libraries. Disabling")
 908     print("         HDF5 support.")
 909
 910 ######################################################################
 911 #
 912 # Finish the configuration
 913 #
 914 main = conf.Finish()
 915
 916 ######################################################################
 917 #
 918 # Collect all non-global variables
 919 #
 920
 921 # Define the universe of supported ISAs
 922 all_isa_list = [ ]
 923 all_gpu_isa_list = [ ]
 924 Export('all_isa_list')
 925 Export('all_gpu_isa_list')
 926
 927 class CpuModel(object):
 928     '''The CpuModel class encapsulates everything the ISA parser needs to
 929     know about a particular CPU model.'''
 930
 931     # Dict of available CPU model objects.  Accessible as CpuModel.dict.
 932     dict = {}
 933
 934     # Constructor.  Automatically adds models to CpuModel.dict.
 935     def __init__(self, name, default=False):
 936         self.name = name           # name of model
 937
 938         # This cpu is enabled by default
 939         self.default = default
 940
 941         # Add self to dict
 942         if name in CpuModel.dict:
 943             raise AttributeError("CpuModel '%s' already registered" % name)
 944         CpuModel.dict[name] = self
 945
 946 Export('CpuModel')
 947
 948 # Sticky variables get saved in the variables file so they persist from
 949 # one invocation to the next (unless overridden, in which case the new
 950 # value becomes sticky).
 951 sticky_vars = Variables(args=ARGUMENTS)
 952 Export('sticky_vars')
 953
 954 # Sticky variables that should be exported
 955 export_vars = []
 956 Export('export_vars')
 957
 958 # For Ruby
 959 all_protocols = []
 960 Export('all_protocols')
 961 protocol_dirs = []
 962 Export('protocol_dirs')
 963 slicc_includes = []
 964 Export('slicc_includes')
 965
 966 # Walk the tree and execute all SConsopts scripts that wil add to the
 967 # above variables
 968 if GetOption('verbose'):
 969     print("Reading SConsopts")
 970 for bdir in [ base_dir ] + extras_dir_list:
 971     if not isdir(bdir):
 972         error("Directory '%s' does not exist." % bdir)
 973     for root, dirs, files in os.walk(bdir):
 974         if 'SConsopts' in files:
 975             if GetOption('verbose'):
 976                 print("Reading", joinpath(root, 'SConsopts'))
 977             SConscript(joinpath(root, 'SConsopts'))
 978
 979 all_isa_list.sort()
 980 all_gpu_isa_list.sort()
 981
 982 sticky_vars.AddVariables(
 983     EnumVariable('TARGET_ISA', 'Target ISA', 'null', all_isa_list),
 984     EnumVariable('TARGET_GPU_ISA', 'Target GPU ISA', 'gcn3', all_gpu_isa_list),
 985     ListVariable('CPU_MODELS', 'CPU models',
 986                  sorted(n for n,m in CpuModel.dict.items() if m.default),
 987                  sorted(CpuModel.dict.keys())),
 988     BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
 989                  False),
 990     BoolVariable('USE_SSE2',
 991                  'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
 992                  False),
 993     BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
 994     BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
 995     BoolVariable('USE_PNG',  'Enable support for PNG images', have_png),
 996     BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models',
 997                  have_kvm),
 998     BoolVariable('USE_TUNTAP',
 999                  'Enable using a tap device to bridge to the host network',
1000                  have_tuntap),
1001     BoolVariable('BUILD_GPU', 'Build the compute-GPU model', False),
1002     EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
1003                   all_protocols),
1004     EnumVariable('BACKTRACE_IMPL', 'Post-mortem dump implementation',
1005                  backtrace_impls[-1], backtrace_impls),
1006     ('NUMBER_BITS_PER_SET', 'Max elements in set (default 64)',
1007                  64),
1008     BoolVariable('USE_HDF5', 'Enable the HDF5 support', have_hdf5),
1009     )
1010
1011 # These variables get exported to #defines in config/*.hh (see src/SConscript).
1012 export_vars += ['USE_FENV', 'TARGET_ISA', 'TARGET_GPU_ISA',
1013                 'USE_POSIX_CLOCK', 'USE_KVM', 'USE_TUNTAP', 'PROTOCOL',
1014                 'HAVE_PROTOBUF', 'HAVE_VALGRIND',
1015                 'HAVE_PERF_ATTR_EXCLUDE_HOST', 'USE_PNG',
1016                 'NUMBER_BITS_PER_SET', 'USE_HDF5']
1017
1018 ###################################################
1019 #
1020 # Define a SCons builder for configuration flag headers.
1021 #
1022 ###################################################
1023
1024 # This function generates a config header file that #defines the
1025 # variable symbol to the current variable setting (0 or 1).  The source
1026 # operands are the name of the variable and a Value node containing the
1027 # value of the variable.
1028 def build_config_file(target, source, env):
1029     (variable, value) = [s.get_contents().decode('utf-8') for s in source]
1030     with open(str(target[0]), 'w') as f:
1031         print('#define', variable, value, file=f)
1032     return None
1033
1034 # Combine the two functions into a scons Action object.
1035 config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1036
1037 # The emitter munges the source & target node lists to reflect what
1038 # we're really doing.
1039 def config_emitter(target, source, env):
1040     # extract variable name from Builder arg
1041     variable = str(target[0])
1042     # True target is config header file
1043     target = joinpath('config', variable.lower() + '.hh')
1044     val = env[variable]
1045     if isinstance(val, bool):
1046         # Force value to 0/1
1047         val = int(val)
1048     elif isinstance(val, str):
1049         val = '"' + val + '"'
1050
1051     # Sources are variable name & value (packaged in SCons Value nodes)
1052     return ([target], [Value(variable), Value(val)])
1053
1054 config_builder = Builder(emitter = config_emitter, action = config_action)
1055
1056 main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1057
1058 ###################################################
1059 #
1060 # Builders for static and shared partially linked object files.
1061 #
1062 ###################################################
1063
1064 partial_static_builder = Builder(action=SCons.Defaults.LinkAction,
1065                                  src_suffix='$OBJSUFFIX',
1066                                  src_builder=['StaticObject', 'Object'],
1067                                  LINKFLAGS='$PLINKFLAGS',
1068                                  LIBS='')
1069
1070 def partial_shared_emitter(target, source, env):
1071     for tgt in target:
1072         tgt.attributes.shared = 1
1073     return (target, source)
1074 partial_shared_builder = Builder(action=SCons.Defaults.ShLinkAction,
1075                                  emitter=partial_shared_emitter,
1076                                  src_suffix='$SHOBJSUFFIX',
1077                                  src_builder='SharedObject',
1078                                  SHLINKFLAGS='$PSHLINKFLAGS',
1079                                  LIBS='')
1080
1081 main.Append(BUILDERS = { 'PartialShared' : partial_shared_builder,
1082                          'PartialStatic' : partial_static_builder })
1083
1084 def add_local_rpath(env, *targets):
1085     '''Set up an RPATH for a library which lives in the build directory.
1086
1087     The construction environment variable BIN_RPATH_PREFIX should be set to
1088     the relative path of the build directory starting from the location of the
1089     binary.'''
1090     for target in targets:
1091         target = env.Entry(target)
1092         if not isinstance(target, SCons.Node.FS.Dir):
1093             target = target.dir
1094         relpath = os.path.relpath(target.abspath, env['BUILDDIR'])
1095         components = [
1096             '\\$$ORIGIN',
1097             '${BIN_RPATH_PREFIX}',
1098             relpath
1099         ]
1100         env.Append(RPATH=[env.Literal(os.path.join(*components))])
1101
1102 if sys.platform != "darwin":
1103     main.Append(LINKFLAGS=Split('-z origin'))
1104
1105 main.AddMethod(add_local_rpath, 'AddLocalRPATH')
1106
1107 # builds in ext are shared across all configs in the build root.
1108 ext_dir = abspath(joinpath(str(main.root), 'ext'))
1109 ext_build_dirs = []
1110 for root, dirs, files in os.walk(ext_dir):
1111     if 'SConscript' in files:
1112         build_dir = os.path.relpath(root, ext_dir)
1113         ext_build_dirs.append(build_dir)
1114         main.SConscript(joinpath(root, 'SConscript'),
1115                         variant_dir=joinpath(build_root, build_dir))
1116
1117 gdb_xml_dir = joinpath(ext_dir, 'gdb-xml')
1118 Export('gdb_xml_dir')
1119
1120 ###################################################
1121 #
1122 # This builder and wrapper method are used to set up a directory with
1123 # switching headers. Those are headers which are in a generic location and
1124 # that include more specific headers from a directory chosen at build time
1125 # based on the current build settings.
1126 #
1127 ###################################################
1128
1129 def build_switching_header(target, source, env):
1130     path = str(target[0])
1131     subdir = str(source[0])
1132     dp, fp = os.path.split(path)
1133     dp = os.path.relpath(os.path.realpath(dp),
1134                          os.path.realpath(env['BUILDDIR']))
1135     with open(path, 'w') as hdr:
1136         print('#include "%s/%s/%s"' % (dp, subdir, fp), file=hdr)
1137
1138 switching_header_action = MakeAction(build_switching_header,
1139                                      Transform('GENERATE'))
1140
1141 switching_header_builder = Builder(action=switching_header_action,
1142                                    source_factory=Value,
1143                                    single_source=True)
1144
1145 main.Append(BUILDERS = { 'SwitchingHeader': switching_header_builder })
1146
1147 def switching_headers(self, headers, source):
1148     for header in headers:
1149         self.SwitchingHeader(header, source)
1150
1151 main.AddMethod(switching_headers, 'SwitchingHeaders')
1152
1153 ###################################################
1154 #
1155 # Define build environments for selected configurations.
1156 #
1157 ###################################################
1158
1159 for variant_path in variant_paths:
1160     if not GetOption('silent'):
1161         print("Building in", variant_path)
1162
1163     # Make a copy of the build-root environment to use for this config.
1164     env = main.Clone()
1165     env['BUILDDIR'] = variant_path
1166
1167     # variant_dir is the tail component of build path, and is used to
1168     # determine the build parameters (e.g., 'X86')
1169     (build_root, variant_dir) = splitpath(variant_path)
1170
1171     # Set env variables according to the build directory config.
1172     sticky_vars.files = []
1173     # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1174     # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1175     # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1176     current_vars_file = joinpath(build_root, 'variables', variant_dir)
1177     if isfile(current_vars_file):
1178         sticky_vars.files.append(current_vars_file)
1179         if not GetOption('silent'):
1180             print("Using saved variables file %s" % current_vars_file)
1181     elif variant_dir in ext_build_dirs:
1182         # Things in ext are built without a variant directory.
1183         continue
1184     else:
1185         # Build dir-specific variables file doesn't exist.
1186
1187         # Make sure the directory is there so we can create it later
1188         opt_dir = dirname(current_vars_file)
1189         if not isdir(opt_dir):
1190             mkdir(opt_dir)
1191
1192         # Get default build variables from source tree.  Variables are
1193         # normally determined by name of $VARIANT_DIR, but can be
1194         # overridden by '--default=' arg on command line.
1195         default = GetOption('default')
1196         opts_dir = joinpath(main.root.abspath, 'build_opts')
1197         if default:
1198             default_vars_files = [joinpath(build_root, 'variables', default),
1199                                   joinpath(opts_dir, default)]
1200         else:
1201             default_vars_files = [joinpath(opts_dir, variant_dir)]
1202         existing_files = list(filter(isfile, default_vars_files))
1203         if existing_files:
1204             default_vars_file = existing_files[0]
1205             sticky_vars.files.append(default_vars_file)
1206             print("Variables file %s not found,\n  using defaults in %s"
1207                   % (current_vars_file, default_vars_file))
1208         else:
1209             error("Cannot find variables file %s or default file(s) %s"
1210                   % (current_vars_file, ' or '.join(default_vars_files)))
1211             Exit(1)
1212
1213     # Apply current variable settings to env
1214     sticky_vars.Update(env)
1215
1216     Help('''
1217 Build variables for {dir}:
1218 {help}
1219 '''.format(dir=variant_dir, help=sticky_vars.GenerateHelpText(env)),
1220          append=True)
1221
1222     # Process variable settings.
1223
1224     if not have_fenv and env['USE_FENV']:
1225         warning("<fenv.h> not available; forcing USE_FENV to False in",
1226                 variant_dir + ".")
1227         env['USE_FENV'] = False
1228
1229     if not env['USE_FENV']:
1230         warning("No IEEE FP rounding mode control in", variant_dir + ".\n"
1231                 "FP results may deviate slightly from other platforms.")
1232
1233     if not have_png and env['USE_PNG']:
1234         warning("<png.h> not available; forcing USE_PNG to False in",
1235                 variant_dir + ".")
1236         env['USE_PNG'] = False
1237
1238     if env['USE_PNG']:
1239         env.Append(LIBS=['png'])
1240
1241     if env['EFENCE']:
1242         env.Append(LIBS=['efence'])
1243
1244     if env['USE_KVM']:
1245         if not have_kvm:
1246             warning("Can not enable KVM, host seems to lack KVM support")
1247             env['USE_KVM'] = False
1248         elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1249             print("Info: KVM support disabled due to unsupported host and "
1250                   "target ISA combination")
1251             env['USE_KVM'] = False
1252
1253     if env['USE_TUNTAP']:
1254         if not have_tuntap:
1255             warning("Can't connect EtherTap with a tap device.")
1256             env['USE_TUNTAP'] = False
1257
1258     if env['BUILD_GPU']:
1259         env.Append(CPPDEFINES=['BUILD_GPU'])
1260
1261     # Warn about missing optional functionality
1262     if env['USE_KVM']:
1263         if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1264             warning("perf_event headers lack support for the exclude_host "
1265                     "attribute. KVM instruction counts will be inaccurate.")
1266
1267     # Save sticky variable settings back to current variables file
1268     sticky_vars.Save(current_vars_file, env)
1269
1270     if env['USE_SSE2']:
1271         env.Append(CCFLAGS=['-msse2'])
1272
1273     env.Append(CCFLAGS='$CCFLAGS_EXTRA')
1274     env.Append(LINKFLAGS='$LDFLAGS_EXTRA')
1275
1276     # The src/SConscript file sets up the build rules in 'env' according
1277     # to the configured variables.  It returns a list of environments,
1278     # one for each variant build (debug, opt, etc.)
1279     SConscript('src/SConscript', variant_dir=variant_path,
1280                exports=['env', 'marshal_env'])
1281
1282 atexit.register(summarize_warnings)