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', 'python2.7-config', 'python2-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++11
 322     main.Append(CXXFLAGS=['-std=c++11'])
 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, "3.1") < 0:
 422             error('clang version 3.1 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 # Platform-specific configuration.  Note again that we assume that all
 579 # builds under a given build root run on the same host platform.
 580 conf = Configure(main,
 581                  conf_dir = joinpath(build_root, '.scons_config'),
 582                  log_file = joinpath(build_root, 'scons_config.log'),
 583                  custom_tests = {
 584         'CheckMember' : CheckMember,
 585         })
 586
 587 # Check if we should compile a 64 bit binary on Mac OS X/Darwin
 588 try:
 589     import platform
 590     uname = platform.uname()
 591     if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
 592         if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
 593             main.Append(CCFLAGS=['-arch', 'x86_64'])
 594             main.Append(CFLAGS=['-arch', 'x86_64'])
 595             main.Append(LINKFLAGS=['-arch', 'x86_64'])
 596             main.Append(ASFLAGS=['-arch', 'x86_64'])
 597 except:
 598     pass
 599
 600 # Recent versions of scons substitute a "Null" object for Configure()
 601 # when configuration isn't necessary, e.g., if the "--help" option is
 602 # present.  Unfortuantely this Null object always returns false,
 603 # breaking all our configuration checks.  We replace it with our own
 604 # more optimistic null object that returns True instead.
 605 if not conf:
 606     def NullCheck(*args, **kwargs):
 607         return True
 608
 609     class NullConf:
 610         def __init__(self, env):
 611             self.env = env
 612         def Finish(self):
 613             return self.env
 614         def __getattr__(self, mname):
 615             return NullCheck
 616
 617     conf = NullConf(main)
 618
 619 # Cache build files in the supplied directory.
 620 if main['M5_BUILD_CACHE']:
 621     print('Using build cache located at', main['M5_BUILD_CACHE'])
 622     CacheDir(main['M5_BUILD_CACHE'])
 623
 624 main['USE_PYTHON'] = not GetOption('without_python')
 625 if main['USE_PYTHON']:
 626     # Find Python include and library directories for embedding the
 627     # interpreter. We rely on python-config to resolve the appropriate
 628     # includes and linker flags. ParseConfig does not seem to understand
 629     # the more exotic linker flags such as -Xlinker and -export-dynamic so
 630     # we add them explicitly below. If you want to link in an alternate
 631     # version of python, see above for instructions on how to invoke
 632     # scons with the appropriate PATH set.
 633
 634     python_config = main.Detect(main['PYTHON_CONFIG'])
 635     if python_config is None:
 636         error("Can't find a suitable python-config, tried %s" % \
 637               main['PYTHON_CONFIG'])
 638
 639     print("Info: Using Python config: %s" % (python_config, ))
 640     if python_config != 'python3-config':
 641         warning('python3-config could not be found.\n'
 642                 'Future releases of gem5 will drop support for python2.')
 643
 644     py_includes = readCommand([python_config, '--includes'],
 645                               exception='').split()
 646     py_includes = list(filter(
 647         lambda s: match(r'.*\/include\/.*',s), py_includes))
 648     # Strip the -I from the include folders before adding them to the
 649     # CPPPATH
 650     py_includes = list(map(
 651         lambda s: s[2:] if s.startswith('-I') else s, py_includes))
 652     main.Append(CPPPATH=py_includes)
 653
 654     # Read the linker flags and split them into libraries and other link
 655     # flags. The libraries are added later through the call the CheckLib.
 656     # Note: starting in Python 3.8 the --embed flag is required to get the
 657     # -lpython3.8 linker flag
 658     retcode, cmd_stdout = readCommandWithReturn(
 659         [python_config, '--ldflags', '--embed'], exception='')
 660     if retcode != 0:
 661         # If --embed isn't detected then we're running python <3.8
 662         retcode, cmd_stdout = readCommandWithReturn(
 663             [python_config, '--ldflags'], exception='')
 664
 665     # Checking retcode again
 666     if retcode != 0:
 667         error("Failing on python-config --ldflags command")
 668
 669     py_ld_flags = cmd_stdout.split()
 670
 671     py_libs = []
 672     for lib in py_ld_flags:
 673          if not lib.startswith('-l'):
 674              main.Append(LINKFLAGS=[lib])
 675          else:
 676              lib = lib[2:]
 677              if lib not in py_libs:
 678                  py_libs.append(lib)
 679
 680     # verify that this stuff works
 681     if not conf.CheckHeader('Python.h', '<>'):
 682         error("Check failed for Python.h header in",
 683                 ' '.join(py_includes), "\n"
 684               "Two possible reasons:\n"
 685               "1. Python headers are not installed (You can install the "
 686               "package python-dev on Ubuntu and RedHat)\n"
 687               "2. SCons is using a wrong C compiler. This can happen if "
 688               "CC has the wrong value.\n"
 689               "CC = %s" % main['CC'])
 690
 691     for lib in py_libs:
 692         if not conf.CheckLib(lib):
 693             error("Can't find library %s required by python." % lib)
 694
 695 main.Prepend(CPPPATH=Dir('ext/pybind11/include/'))
 696 # Bare minimum environment that only includes python
 697 marshal_env = main.Clone()
 698 marshal_env.Append(CCFLAGS='$MARSHAL_CCFLAGS_EXTRA')
 699 marshal_env.Append(LINKFLAGS='$MARSHAL_LDFLAGS_EXTRA')
 700
 701 # On Solaris you need to use libsocket for socket ops
 702 if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
 703    if not conf.CheckLibWithHeader('socket', 'sys/socket.h',
 704                                   'C++', 'accept(0,0,0);'):
 705        error("Can't find library with socket calls (e.g. accept()).")
 706
 707 # Check for zlib.  If the check passes, libz will be automatically
 708 # added to the LIBS environment variable.
 709 if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
 710     error('Did not find needed zlib compression library '
 711           'and/or zlib.h header file.\n'
 712           'Please install zlib and try again.')
 713
 714 # If we have the protobuf compiler, also make sure we have the
 715 # development libraries. If the check passes, libprotobuf will be
 716 # automatically added to the LIBS environment variable. After
 717 # this, we can use the HAVE_PROTOBUF flag to determine if we have
 718 # got both protoc and libprotobuf available.
 719 main['HAVE_PROTOBUF'] = main['HAVE_PROTOC'] and \
 720     conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
 721                             'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
 722
 723 # Valgrind gets much less confused if you tell it when you're using
 724 # alternative stacks.
 725 main['HAVE_VALGRIND'] = conf.CheckCHeader('valgrind/valgrind.h')
 726
 727 # If we have the compiler but not the library, print another warning.
 728 if main['HAVE_PROTOC'] and not main['HAVE_PROTOBUF']:
 729     warning('Did not find protocol buffer library and/or headers.\n'
 730             'Please install libprotobuf-dev for tracing support.')
 731
 732 # Check for librt.
 733 have_posix_clock = \
 734     conf.CheckLibWithHeader(None, 'time.h', 'C',
 735                             'clock_nanosleep(0,0,NULL,NULL);') or \
 736     conf.CheckLibWithHeader('rt', 'time.h', 'C',
 737                             'clock_nanosleep(0,0,NULL,NULL);')
 738
 739 have_posix_timers = \
 740     conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
 741                             'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
 742
 743 if not GetOption('without_tcmalloc'):
 744     if conf.CheckLib('tcmalloc'):
 745         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 746     elif conf.CheckLib('tcmalloc_minimal'):
 747         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 748     else:
 749         warning("You can get a 12% performance improvement by "
 750                 "installing tcmalloc (libgoogle-perftools-dev package "
 751                 "on Ubuntu or RedHat).")
 752
 753
 754 # Detect back trace implementations. The last implementation in the
 755 # list will be used by default.
 756 backtrace_impls = [ "none" ]
 757
 758 backtrace_checker = 'char temp;' + \
 759     ' backtrace_symbols_fd((void*)&temp, 0, 0);'
 760 if conf.CheckLibWithHeader(None, 'execinfo.h', 'C', backtrace_checker):
 761     backtrace_impls.append("glibc")
 762 elif conf.CheckLibWithHeader('execinfo', 'execinfo.h', 'C',
 763                              backtrace_checker):
 764     # NetBSD and FreeBSD need libexecinfo.
 765     backtrace_impls.append("glibc")
 766     main.Append(LIBS=['execinfo'])
 767
 768 if backtrace_impls[-1] == "none":
 769     default_backtrace_impl = "none"
 770     warning("No suitable back trace implementation found.")
 771
 772 if not have_posix_clock:
 773     warning("Can't find library for POSIX clocks.")
 774
 775 # Check for <fenv.h> (C99 FP environment control)
 776 have_fenv = conf.CheckHeader('fenv.h', '<>')
 777 if not have_fenv:
 778     warning("Header file <fenv.h> not found.\n"
 779             "This host has no IEEE FP rounding mode control.")
 780
 781 # Check for <png.h> (libpng library needed if wanting to dump
 782 # frame buffer image in png format)
 783 have_png = conf.CheckHeader('png.h', '<>')
 784 if not have_png:
 785     warning("Header file <png.h> not found.\n"
 786             "This host has no libpng library.\n"
 787             "Disabling support for PNG framebuffers.")
 788
 789 # Check if we should enable KVM-based hardware virtualization. The API
 790 # we rely on exists since version 2.6.36 of the kernel, but somehow
 791 # the KVM_API_VERSION does not reflect the change. We test for one of
 792 # the types as a fall back.
 793 have_kvm = conf.CheckHeader('linux/kvm.h', '<>')
 794 if not have_kvm:
 795     print("Info: Compatible header file <linux/kvm.h> not found, "
 796           "disabling KVM support.")
 797
 798 # Check if the TUN/TAP driver is available.
 799 have_tuntap = conf.CheckHeader('linux/if_tun.h', '<>')
 800 if not have_tuntap:
 801     print("Info: Compatible header file <linux/if_tun.h> not found.")
 802
 803 # x86 needs support for xsave. We test for the structure here since we
 804 # won't be able to run new tests by the time we know which ISA we're
 805 # targeting.
 806 have_kvm_xsave = conf.CheckTypeSize('struct kvm_xsave',
 807                                     '#include <linux/kvm.h>') != 0
 808
 809 # Check if the requested target ISA is compatible with the host
 810 def is_isa_kvm_compatible(isa):
 811     try:
 812         import platform
 813         host_isa = platform.machine()
 814     except:
 815         warning("Failed to determine host ISA.")
 816         return False
 817
 818     if not have_posix_timers:
 819         warning("Can not enable KVM, host seems to lack support "
 820                 "for POSIX timers")
 821         return False
 822
 823     if isa == "arm":
 824         return host_isa in ( "armv7l", "aarch64" )
 825     elif isa == "x86":
 826         if host_isa != "x86_64":
 827             return False
 828
 829         if not have_kvm_xsave:
 830             warning("KVM on x86 requires xsave support in kernel headers.")
 831             return False
 832
 833         return True
 834     else:
 835         return False
 836
 837
 838 # Check if the exclude_host attribute is available. We want this to
 839 # get accurate instruction counts in KVM.
 840 main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
 841     'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
 842
 843 def check_hdf5():
 844     return \
 845         conf.CheckLibWithHeader('hdf5', 'hdf5.h', 'C',
 846                                 'H5Fcreate("", 0, 0, 0);') and \
 847         conf.CheckLibWithHeader('hdf5_cpp', 'H5Cpp.h', 'C++',
 848                                 'H5::H5File("", 0);')
 849
 850 def check_hdf5_pkg(name):
 851     print("Checking for %s using pkg-config..." % name, end="")
 852     if not have_pkg_config:
 853         print(" pkg-config not found")
 854         return False
 855
 856     try:
 857         main.ParseConfig('pkg-config --cflags-only-I --libs-only-L %s' % name)
 858         print(" yes")
 859         return True
 860     except:
 861         print(" no")
 862         return False
 863
 864 # Check if there is a pkg-config configuration for hdf5. If we find
 865 # it, setup the environment to enable linking and header inclusion. We
 866 # don't actually try to include any headers or link with hdf5 at this
 867 # stage.
 868 if not check_hdf5_pkg('hdf5-serial'):
 869     check_hdf5_pkg('hdf5')
 870
 871 # Check if the HDF5 libraries can be found. This check respects the
 872 # include path and library path provided by pkg-config. We perform
 873 # this check even if there isn't a pkg-config configuration for hdf5
 874 # since some installations don't use pkg-config.
 875 have_hdf5 = check_hdf5()
 876 if not have_hdf5:
 877     print("Warning: Couldn't find any HDF5 C++ libraries. Disabling")
 878     print("         HDF5 support.")
 879
 880 ######################################################################
 881 #
 882 # Finish the configuration
 883 #
 884 main = conf.Finish()
 885
 886 ######################################################################
 887 #
 888 # Collect all non-global variables
 889 #
 890
 891 # Define the universe of supported ISAs
 892 all_isa_list = [ ]
 893 all_gpu_isa_list = [ ]
 894 Export('all_isa_list')
 895 Export('all_gpu_isa_list')
 896
 897 class CpuModel(object):
 898     '''The CpuModel class encapsulates everything the ISA parser needs to
 899     know about a particular CPU model.'''
 900
 901     # Dict of available CPU model objects.  Accessible as CpuModel.dict.
 902     dict = {}
 903
 904     # Constructor.  Automatically adds models to CpuModel.dict.
 905     def __init__(self, name, default=False):
 906         self.name = name           # name of model
 907
 908         # This cpu is enabled by default
 909         self.default = default
 910
 911         # Add self to dict
 912         if name in CpuModel.dict:
 913             raise AttributeError("CpuModel '%s' already registered" % name)
 914         CpuModel.dict[name] = self
 915
 916 Export('CpuModel')
 917
 918 # Sticky variables get saved in the variables file so they persist from
 919 # one invocation to the next (unless overridden, in which case the new
 920 # value becomes sticky).
 921 sticky_vars = Variables(args=ARGUMENTS)
 922 Export('sticky_vars')
 923
 924 # Sticky variables that should be exported
 925 export_vars = []
 926 Export('export_vars')
 927
 928 # For Ruby
 929 all_protocols = []
 930 Export('all_protocols')
 931 protocol_dirs = []
 932 Export('protocol_dirs')
 933 slicc_includes = []
 934 Export('slicc_includes')
 935
 936 # Walk the tree and execute all SConsopts scripts that wil add to the
 937 # above variables
 938 if GetOption('verbose'):
 939     print("Reading SConsopts")
 940 for bdir in [ base_dir ] + extras_dir_list:
 941     if not isdir(bdir):
 942         error("Directory '%s' does not exist." % bdir)
 943     for root, dirs, files in os.walk(bdir):
 944         if 'SConsopts' in files:
 945             if GetOption('verbose'):
 946                 print("Reading", joinpath(root, 'SConsopts'))
 947             SConscript(joinpath(root, 'SConsopts'))
 948
 949 all_isa_list.sort()
 950 all_gpu_isa_list.sort()
 951
 952 sticky_vars.AddVariables(
 953     EnumVariable('TARGET_ISA', 'Target ISA', 'null', all_isa_list),
 954     EnumVariable('TARGET_GPU_ISA', 'Target GPU ISA', 'gcn3', all_gpu_isa_list),
 955     ListVariable('CPU_MODELS', 'CPU models',
 956                  sorted(n for n,m in CpuModel.dict.items() if m.default),
 957                  sorted(CpuModel.dict.keys())),
 958     BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
 959                  False),
 960     BoolVariable('USE_SSE2',
 961                  'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
 962                  False),
 963     BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
 964     BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
 965     BoolVariable('USE_PNG',  'Enable support for PNG images', have_png),
 966     BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models',
 967                  have_kvm),
 968     BoolVariable('USE_TUNTAP',
 969                  'Enable using a tap device to bridge to the host network',
 970                  have_tuntap),
 971     BoolVariable('BUILD_GPU', 'Build the compute-GPU model', False),
 972     EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
 973                   all_protocols),
 974     EnumVariable('BACKTRACE_IMPL', 'Post-mortem dump implementation',
 975                  backtrace_impls[-1], backtrace_impls),
 976     ('NUMBER_BITS_PER_SET', 'Max elements in set (default 64)',
 977                  64),
 978     BoolVariable('USE_HDF5', 'Enable the HDF5 support', have_hdf5),
 979     )
 980
 981 # These variables get exported to #defines in config/*.hh (see src/SConscript).
 982 export_vars += ['USE_FENV', 'TARGET_ISA', 'TARGET_GPU_ISA',
 983                 'USE_POSIX_CLOCK', 'USE_KVM', 'USE_TUNTAP', 'PROTOCOL',
 984                 'HAVE_PROTOBUF', 'HAVE_VALGRIND',
 985                 'HAVE_PERF_ATTR_EXCLUDE_HOST', 'USE_PNG',
 986                 'NUMBER_BITS_PER_SET', 'USE_HDF5']
 987
 988 ###################################################
 989 #
 990 # Define a SCons builder for configuration flag headers.
 991 #
 992 ###################################################
 993
 994 # This function generates a config header file that #defines the
 995 # variable symbol to the current variable setting (0 or 1).  The source
 996 # operands are the name of the variable and a Value node containing the
 997 # value of the variable.
 998 def build_config_file(target, source, env):
 999     (variable, value) = [s.get_contents().decode('utf-8') for s in source]
1000     with open(str(target[0]), 'w') as f:
1001         print('#define', variable, value, file=f)
1002     return None
1003
1004 # Combine the two functions into a scons Action object.
1005 config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1006
1007 # The emitter munges the source & target node lists to reflect what
1008 # we're really doing.
1009 def config_emitter(target, source, env):
1010     # extract variable name from Builder arg
1011     variable = str(target[0])
1012     # True target is config header file
1013     target = joinpath('config', variable.lower() + '.hh')
1014     val = env[variable]
1015     if isinstance(val, bool):
1016         # Force value to 0/1
1017         val = int(val)
1018     elif isinstance(val, str):
1019         val = '"' + val + '"'
1020
1021     # Sources are variable name & value (packaged in SCons Value nodes)
1022     return ([target], [Value(variable), Value(val)])
1023
1024 config_builder = Builder(emitter = config_emitter, action = config_action)
1025
1026 main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1027
1028 ###################################################
1029 #
1030 # Builders for static and shared partially linked object files.
1031 #
1032 ###################################################
1033
1034 partial_static_builder = Builder(action=SCons.Defaults.LinkAction,
1035                                  src_suffix='$OBJSUFFIX',
1036                                  src_builder=['StaticObject', 'Object'],
1037                                  LINKFLAGS='$PLINKFLAGS',
1038                                  LIBS='')
1039
1040 def partial_shared_emitter(target, source, env):
1041     for tgt in target:
1042         tgt.attributes.shared = 1
1043     return (target, source)
1044 partial_shared_builder = Builder(action=SCons.Defaults.ShLinkAction,
1045                                  emitter=partial_shared_emitter,
1046                                  src_suffix='$SHOBJSUFFIX',
1047                                  src_builder='SharedObject',
1048                                  SHLINKFLAGS='$PSHLINKFLAGS',
1049                                  LIBS='')
1050
1051 main.Append(BUILDERS = { 'PartialShared' : partial_shared_builder,
1052                          'PartialStatic' : partial_static_builder })
1053
1054 def add_local_rpath(env, *targets):
1055     '''Set up an RPATH for a library which lives in the build directory.
1056
1057     The construction environment variable BIN_RPATH_PREFIX should be set to
1058     the relative path of the build directory starting from the location of the
1059     binary.'''
1060     for target in targets:
1061         target = env.Entry(target)
1062         if not isinstance(target, SCons.Node.FS.Dir):
1063             target = target.dir
1064         relpath = os.path.relpath(target.abspath, env['BUILDDIR'])
1065         components = [
1066             '\\$$ORIGIN',
1067             '${BIN_RPATH_PREFIX}',
1068             relpath
1069         ]
1070         env.Append(RPATH=[env.Literal(os.path.join(*components))])
1071
1072 if sys.platform != "darwin":
1073     main.Append(LINKFLAGS=Split('-z origin'))
1074
1075 main.AddMethod(add_local_rpath, 'AddLocalRPATH')
1076
1077 # builds in ext are shared across all configs in the build root.
1078 ext_dir = abspath(joinpath(str(main.root), 'ext'))
1079 ext_build_dirs = []
1080 for root, dirs, files in os.walk(ext_dir):
1081     if 'SConscript' in files:
1082         build_dir = os.path.relpath(root, ext_dir)
1083         ext_build_dirs.append(build_dir)
1084         main.SConscript(joinpath(root, 'SConscript'),
1085                         variant_dir=joinpath(build_root, build_dir))
1086
1087 gdb_xml_dir = joinpath(ext_dir, 'gdb-xml')
1088 Export('gdb_xml_dir')
1089
1090 ###################################################
1091 #
1092 # This builder and wrapper method are used to set up a directory with
1093 # switching headers. Those are headers which are in a generic location and
1094 # that include more specific headers from a directory chosen at build time
1095 # based on the current build settings.
1096 #
1097 ###################################################
1098
1099 def build_switching_header(target, source, env):
1100     path = str(target[0])
1101     subdir = str(source[0])
1102     dp, fp = os.path.split(path)
1103     dp = os.path.relpath(os.path.realpath(dp),
1104                          os.path.realpath(env['BUILDDIR']))
1105     with open(path, 'w') as hdr:
1106         print('#include "%s/%s/%s"' % (dp, subdir, fp), file=hdr)
1107
1108 switching_header_action = MakeAction(build_switching_header,
1109                                      Transform('GENERATE'))
1110
1111 switching_header_builder = Builder(action=switching_header_action,
1112                                    source_factory=Value,
1113                                    single_source=True)
1114
1115 main.Append(BUILDERS = { 'SwitchingHeader': switching_header_builder })
1116
1117 def switching_headers(self, headers, source):
1118     for header in headers:
1119         self.SwitchingHeader(header, source)
1120
1121 main.AddMethod(switching_headers, 'SwitchingHeaders')
1122
1123 ###################################################
1124 #
1125 # Define build environments for selected configurations.
1126 #
1127 ###################################################
1128
1129 for variant_path in variant_paths:
1130     if not GetOption('silent'):
1131         print("Building in", variant_path)
1132
1133     # Make a copy of the build-root environment to use for this config.
1134     env = main.Clone()
1135     env['BUILDDIR'] = variant_path
1136
1137     # variant_dir is the tail component of build path, and is used to
1138     # determine the build parameters (e.g., 'X86')
1139     (build_root, variant_dir) = splitpath(variant_path)
1140
1141     # Set env variables according to the build directory config.
1142     sticky_vars.files = []
1143     # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1144     # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1145     # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1146     current_vars_file = joinpath(build_root, 'variables', variant_dir)
1147     if isfile(current_vars_file):
1148         sticky_vars.files.append(current_vars_file)
1149         if not GetOption('silent'):
1150             print("Using saved variables file %s" % current_vars_file)
1151     elif variant_dir in ext_build_dirs:
1152         # Things in ext are built without a variant directory.
1153         continue
1154     else:
1155         # Build dir-specific variables file doesn't exist.
1156
1157         # Make sure the directory is there so we can create it later
1158         opt_dir = dirname(current_vars_file)
1159         if not isdir(opt_dir):
1160             mkdir(opt_dir)
1161
1162         # Get default build variables from source tree.  Variables are
1163         # normally determined by name of $VARIANT_DIR, but can be
1164         # overridden by '--default=' arg on command line.
1165         default = GetOption('default')
1166         opts_dir = joinpath(main.root.abspath, 'build_opts')
1167         if default:
1168             default_vars_files = [joinpath(build_root, 'variables', default),
1169                                   joinpath(opts_dir, default)]
1170         else:
1171             default_vars_files = [joinpath(opts_dir, variant_dir)]
1172         existing_files = list(filter(isfile, default_vars_files))
1173         if existing_files:
1174             default_vars_file = existing_files[0]
1175             sticky_vars.files.append(default_vars_file)
1176             print("Variables file %s not found,\n  using defaults in %s"
1177                   % (current_vars_file, default_vars_file))
1178         else:
1179             error("Cannot find variables file %s or default file(s) %s"
1180                   % (current_vars_file, ' or '.join(default_vars_files)))
1181             Exit(1)
1182
1183     # Apply current variable settings to env
1184     sticky_vars.Update(env)
1185
1186     Help('''
1187 Build variables for {dir}:
1188 {help}
1189 '''.format(dir=variant_dir, help=sticky_vars.GenerateHelpText(env)),
1190          append=True)
1191
1192     # Process variable settings.
1193
1194     if not have_fenv and env['USE_FENV']:
1195         warning("<fenv.h> not available; forcing USE_FENV to False in",
1196                 variant_dir + ".")
1197         env['USE_FENV'] = False
1198
1199     if not env['USE_FENV']:
1200         warning("No IEEE FP rounding mode control in", variant_dir + ".\n"
1201                 "FP results may deviate slightly from other platforms.")
1202
1203     if not have_png and env['USE_PNG']:
1204         warning("<png.h> not available; forcing USE_PNG to False in",
1205                 variant_dir + ".")
1206         env['USE_PNG'] = False
1207
1208     if env['USE_PNG']:
1209         env.Append(LIBS=['png'])
1210
1211     if env['EFENCE']:
1212         env.Append(LIBS=['efence'])
1213
1214     if env['USE_KVM']:
1215         if not have_kvm:
1216             warning("Can not enable KVM, host seems to lack KVM support")
1217             env['USE_KVM'] = False
1218         elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1219             print("Info: KVM support disabled due to unsupported host and "
1220                   "target ISA combination")
1221             env['USE_KVM'] = False
1222
1223     if env['USE_TUNTAP']:
1224         if not have_tuntap:
1225             warning("Can't connect EtherTap with a tap device.")
1226             env['USE_TUNTAP'] = False
1227
1228     if env['BUILD_GPU']:
1229         env.Append(CPPDEFINES=['BUILD_GPU'])
1230
1231     # Warn about missing optional functionality
1232     if env['USE_KVM']:
1233         if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1234             warning("perf_event headers lack support for the exclude_host "
1235                     "attribute. KVM instruction counts will be inaccurate.")
1236
1237     # Save sticky variable settings back to current variables file
1238     sticky_vars.Save(current_vars_file, env)
1239
1240     if env['USE_SSE2']:
1241         env.Append(CCFLAGS=['-msse2'])
1242
1243     env.Append(CCFLAGS='$CCFLAGS_EXTRA')
1244     env.Append(LINKFLAGS='$LDFLAGS_EXTRA')
1245
1246     # The src/SConscript file sets up the build rules in 'env' according
1247     # to the configured variables.  It returns a list of environments,
1248     # one for each variant build (debug, opt, etc.)
1249     SConscript('src/SConscript', variant_dir=variant_path,
1250                exports=['env', 'marshal_env'])
1251
1252 atexit.register(summarize_warnings)