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      [ 'python2.7-config', 'python-config', 'python3-config' ]),
 242     ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
 243     ('BATCH', 'Use batch pool for build and tests', False),
 244     ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
 245     ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
 246     ('EXTRAS', 'Add extra directories to the compilation', '')
 247     )
 248
 249 # Update main environment with values from ARGUMENTS & global_vars_file
 250 global_vars.Update(main)
 251 Help('''
 252 Global build variables:
 253 {help}
 254 '''.format(help=global_vars.GenerateHelpText(main)), append=True)
 255
 256 # Save sticky variable settings back to current variables file
 257 global_vars.Save(global_vars_file, main)
 258
 259 # Parse EXTRAS variable to build list of all directories where we're
 260 # look for sources etc.  This list is exported as extras_dir_list.
 261 base_dir = main.srcdir.abspath
 262 if main['EXTRAS']:
 263     extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
 264 else:
 265     extras_dir_list = []
 266
 267 Export('base_dir')
 268 Export('extras_dir_list')
 269
 270 # the ext directory should be on the #includes path
 271 main.Append(CPPPATH=[Dir('ext')])
 272
 273 # Add shared top-level headers
 274 main.Prepend(CPPPATH=Dir('include'))
 275
 276 if GetOption('verbose'):
 277     def MakeAction(action, string, *args, **kwargs):
 278         return Action(action, *args, **kwargs)
 279 else:
 280     MakeAction = Action
 281     main['CCCOMSTR']        = Transform("CC")
 282     main['CXXCOMSTR']       = Transform("CXX")
 283     main['ASCOMSTR']        = Transform("AS")
 284     main['ARCOMSTR']        = Transform("AR", 0)
 285     main['LINKCOMSTR']      = Transform("LINK", 0)
 286     main['SHLINKCOMSTR']    = Transform("SHLINK", 0)
 287     main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
 288     main['M4COMSTR']        = Transform("M4")
 289     main['SHCCCOMSTR']      = Transform("SHCC")
 290     main['SHCXXCOMSTR']     = Transform("SHCXX")
 291 Export('MakeAction')
 292
 293 # Initialize the Link-Time Optimization (LTO) flags
 294 main['LTO_CCFLAGS'] = []
 295 main['LTO_LDFLAGS'] = []
 296
 297 # According to the readme, tcmalloc works best if the compiler doesn't
 298 # assume that we're using the builtin malloc and friends. These flags
 299 # are compiler-specific, so we need to set them after we detect which
 300 # compiler we're using.
 301 main['TCMALLOC_CCFLAGS'] = []
 302
 303 CXX_version = readCommand([main['CXX'],'--version'], exception=False)
 304 CXX_V = readCommand([main['CXX'],'-V'], exception=False)
 305
 306 main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
 307 main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
 308 if main['GCC'] + main['CLANG'] > 1:
 309     error('Two compilers enabled at once?')
 310
 311 # Set up default C++ compiler flags
 312 if main['GCC'] or main['CLANG']:
 313     # As gcc and clang share many flags, do the common parts here
 314     main.Append(CCFLAGS=['-pipe'])
 315     main.Append(CCFLAGS=['-fno-strict-aliasing'])
 316     # Enable -Wall and -Wextra and then disable the few warnings that
 317     # we consistently violate
 318     main.Append(CCFLAGS=['-Wall', '-Wundef', '-Wextra',
 319                          '-Wno-sign-compare', '-Wno-unused-parameter'])
 320     # We always compile using C++11
 321     main.Append(CXXFLAGS=['-std=c++11'])
 322     if sys.platform.startswith('freebsd'):
 323         main.Append(CCFLAGS=['-I/usr/local/include'])
 324         main.Append(CXXFLAGS=['-I/usr/local/include'])
 325
 326     # On Mac OS X/Darwin the default linker doesn't support the
 327     # option --as-needed
 328     if sys.platform != "darwin":
 329         main.Append(LINKFLAGS='-Wl,--as-needed')
 330     main['FILTER_PSHLINKFLAGS'] = lambda x: str(x).replace(' -shared', '')
 331     main['PSHLINKFLAGS'] = main.subst('${FILTER_PSHLINKFLAGS(SHLINKFLAGS)}')
 332     if GetOption('gold_linker'):
 333         main.Append(LINKFLAGS='-fuse-ld=gold')
 334     main['PLINKFLAGS'] = main.get('LINKFLAGS')
 335     shared_partial_flags = ['-r', '-nostdlib']
 336     main.Append(PSHLINKFLAGS=shared_partial_flags)
 337     main.Append(PLINKFLAGS=shared_partial_flags)
 338
 339     # Treat warnings as errors but white list some warnings that we
 340     # want to allow (e.g., deprecation warnings).
 341     main.Append(CCFLAGS=['-Werror',
 342                          '-Wno-error=deprecated-declarations',
 343                          '-Wno-error=deprecated',
 344                         ])
 345 else:
 346     error('\n'.join((
 347           "Don't know what compiler options to use for your compiler.",
 348           "compiler: " + main['CXX'],
 349           "version: " + CXX_version.replace('\n', '<nl>') if
 350                 CXX_version else 'COMMAND NOT FOUND!',
 351           "If you're trying to use a compiler other than GCC",
 352           "or clang, there appears to be something wrong with your",
 353           "environment.",
 354           "",
 355           "If you are trying to use a compiler other than those listed",
 356           "above you will need to ease fix SConstruct and ",
 357           "src/SConscript to support that compiler.")))
 358
 359 if main['GCC']:
 360     gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
 361     if compareVersions(gcc_version, "5") < 0:
 362         error('gcc version 5 or newer required.\n'
 363               'Installed version:', gcc_version)
 364         Exit(1)
 365
 366     main['GCC_VERSION'] = gcc_version
 367
 368     # Incremental linking with LTO is currently broken in gcc versions
 369     # 4.9 and above. A version where everything works completely hasn't
 370     # yet been identified.
 371     #
 372     # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548
 373     main['BROKEN_INCREMENTAL_LTO'] = True
 374
 375     if compareVersions(gcc_version, '6.0') >= 0:
 376         # gcc versions 6.0 and greater accept an -flinker-output flag which
 377         # selects what type of output the linker should generate. This is
 378         # necessary for incremental lto to work, but is also broken in
 379         # current versions of gcc. It may not be necessary in future
 380         # versions. We add it here since it might be, and as a reminder that
 381         # it exists. It's excluded if lto is being forced.
 382         #
 383         # https://gcc.gnu.org/gcc-6/changes.html
 384         # https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03161.html
 385         # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866
 386         if not GetOption('force_lto'):
 387             main.Append(PSHLINKFLAGS='-flinker-output=rel')
 388             main.Append(PLINKFLAGS='-flinker-output=rel')
 389
 390     disable_lto = GetOption('no_lto')
 391     if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \
 392             not GetOption('force_lto'):
 393         warning('Your compiler doesn\'t support incremental linking and lto '
 394                 'at the same time, so lto is being disabled. To force lto on '
 395                 'anyway, use the --force-lto option. That will disable '
 396                 'partial linking.')
 397         disable_lto = True
 398
 399     # Add the appropriate Link-Time Optimization (LTO) flags
 400     # unless LTO is explicitly turned off. Note that these flags
 401     # are only used by the fast target.
 402     if not disable_lto:
 403         # Pass the LTO flag when compiling to produce GIMPLE
 404         # output, we merely create the flags here and only append
 405         # them later
 406         main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 407
 408         # Use the same amount of jobs for LTO as we are running
 409         # scons with
 410         main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 411
 412     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
 413                                   '-fno-builtin-realloc', '-fno-builtin-free'])
 414
 415 elif main['CLANG']:
 416     clang_version_re = re.compile(".* version (\d+\.\d+)")
 417     clang_version_match = clang_version_re.search(CXX_version)
 418     if (clang_version_match):
 419         clang_version = clang_version_match.groups()[0]
 420         if compareVersions(clang_version, "3.9") < 0:
 421             error('clang version 3.9 or newer required.\n'
 422                   'Installed version:', clang_version)
 423     else:
 424         error('Unable to determine clang version.')
 425
 426     # clang has a few additional warnings that we disable, extraneous
 427     # parantheses are allowed due to Ruby's printing of the AST,
 428     # finally self assignments are allowed as the generated CPU code
 429     # is relying on this
 430     main.Append(CCFLAGS=['-Wno-parentheses',
 431                          '-Wno-self-assign',
 432                          # Some versions of libstdc++ (4.8?) seem to
 433                          # use struct hash and class hash
 434                          # interchangeably.
 435                          '-Wno-mismatched-tags',
 436                          ])
 437     if sys.platform != "darwin" and \
 438        compareVersions(clang_version, "10.0") >= 0:
 439         main.Append(CCFLAGS=['-Wno-c99-designator'])
 440
 441     if compareVersions(clang_version, "8.0") >= 0:
 442         main.Append(CCFLAGS=['-Wno-defaulted-function-deleted'])
 443
 444     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
 445
 446     # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
 447     # opposed to libstdc++, as the later is dated.
 448     if sys.platform == "darwin":
 449         main.Append(CXXFLAGS=['-stdlib=libc++'])
 450         main.Append(LIBS=['c++'])
 451
 452     # On FreeBSD we need libthr.
 453     if sys.platform.startswith('freebsd'):
 454         main.Append(LIBS=['thr'])
 455
 456 # Add sanitizers flags
 457 sanitizers=[]
 458 if GetOption('with_ubsan'):
 459     sanitizers.append('undefined')
 460 if GetOption('with_asan'):
 461     # Available for gcc >= 5 or llvm >= 3.1 both a requirement
 462     # by the build system
 463     sanitizers.append('address')
 464     suppressions_file = Dir('util').File('lsan-suppressions').get_abspath()
 465     suppressions_opt = 'suppressions=%s' % suppressions_file
 466     main['ENV']['LSAN_OPTIONS'] = ':'.join([suppressions_opt,
 467                                             'print_suppressions=0'])
 468     print()
 469     warning('To suppress false positive leaks, set the LSAN_OPTIONS '
 470             'environment variable to "%s" when running gem5' %
 471             suppressions_opt)
 472     warning('LSAN_OPTIONS=suppressions=%s' % suppressions_opt)
 473     print()
 474 if sanitizers:
 475     sanitizers = ','.join(sanitizers)
 476     if main['GCC'] or main['CLANG']:
 477         main.Append(CCFLAGS=['-fsanitize=%s' % sanitizers,
 478                              '-fno-omit-frame-pointer'],
 479                     LINKFLAGS='-fsanitize=%s' % sanitizers)
 480     else:
 481         warning("Don't know how to enable %s sanitizer(s) for your "
 482                 "compiler." % sanitizers)
 483
 484 # Set up common yacc/bison flags (needed for Ruby)
 485 main['YACCFLAGS'] = '-d'
 486 main['YACCHXXFILESUFFIX'] = '.hh'
 487
 488 # Do this after we save setting back, or else we'll tack on an
 489 # extra 'qdo' every time we run scons.
 490 if main['BATCH']:
 491     main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
 492     main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
 493     main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
 494     main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
 495     main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
 496
 497 if sys.platform == 'cygwin':
 498     # cygwin has some header file issues...
 499     main.Append(CCFLAGS=["-Wno-uninitialized"])
 500
 501
 502 have_pkg_config = readCommand(['pkg-config', '--version'], exception='')
 503
 504 # Check for the protobuf compiler
 505 try:
 506     main['HAVE_PROTOC'] = True
 507     protoc_version = readCommand([main['PROTOC'], '--version']).split()
 508
 509     # First two words should be "libprotoc x.y.z"
 510     if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
 511         warning('Protocol buffer compiler (protoc) not found.\n'
 512                 'Please install protobuf-compiler for tracing support.')
 513         main['HAVE_PROTOC'] = False
 514     else:
 515         # Based on the availability of the compress stream wrappers,
 516         # require 2.1.0
 517         min_protoc_version = '2.1.0'
 518         if compareVersions(protoc_version[1], min_protoc_version) < 0:
 519             warning('protoc version', min_protoc_version,
 520                     'or newer required.\n'
 521                     'Installed version:', protoc_version[1])
 522             main['HAVE_PROTOC'] = False
 523         else:
 524             # Attempt to determine the appropriate include path and
 525             # library path using pkg-config, that means we also need to
 526             # check for pkg-config. Note that it is possible to use
 527             # protobuf without the involvement of pkg-config. Later on we
 528             # check go a library config check and at that point the test
 529             # will fail if libprotobuf cannot be found.
 530             if have_pkg_config:
 531                 try:
 532                     # Attempt to establish what linking flags to add for
 533                     # protobuf
 534                     # using pkg-config
 535                     main.ParseConfig(
 536                             'pkg-config --cflags --libs-only-L protobuf')
 537                 except:
 538                     warning('pkg-config could not get protobuf flags.')
 539 except Exception as e:
 540     warning('While checking protoc version:', str(e))
 541     main['HAVE_PROTOC'] = False
 542
 543 # Check for 'timeout' from GNU coreutils. If present, regressions will
 544 # be run with a time limit. We require version 8.13 since we rely on
 545 # support for the '--foreground' option.
 546 if sys.platform.startswith('freebsd'):
 547     timeout_lines = readCommand(['gtimeout', '--version'],
 548                                 exception='').splitlines()
 549 else:
 550     timeout_lines = readCommand(['timeout', '--version'],
 551                                 exception='').splitlines()
 552 # Get the first line and tokenize it
 553 timeout_version = timeout_lines[0].split() if timeout_lines else []
 554 main['TIMEOUT'] =  timeout_version and \
 555     compareVersions(timeout_version[-1], '8.13') >= 0
 556
 557 # Add a custom Check function to test for structure members.
 558 def CheckMember(context, include, decl, member, include_quotes="<>"):
 559     context.Message("Checking for member %s in %s..." %
 560                     (member, decl))
 561     text = """
 562 #include %(header)s
 563 int main(){
 564   %(decl)s test;
 565   (void)test.%(member)s;
 566   return 0;
 567 };
 568 """ % { "header" : include_quotes[0] + include + include_quotes[1],
 569         "decl" : decl,
 570         "member" : member,
 571         }
 572
 573     ret = context.TryCompile(text, extension=".cc")
 574     context.Result(ret)
 575     return ret
 576
 577 # Platform-specific configuration.  Note again that we assume that all
 578 # builds under a given build root run on the same host platform.
 579 conf = Configure(main,
 580                  conf_dir = joinpath(build_root, '.scons_config'),
 581                  log_file = joinpath(build_root, 'scons_config.log'),
 582                  custom_tests = {
 583         'CheckMember' : CheckMember,
 584         })
 585
 586 # Check if we should compile a 64 bit binary on Mac OS X/Darwin
 587 try:
 588     import platform
 589     uname = platform.uname()
 590     if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
 591         if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
 592             main.Append(CCFLAGS=['-arch', 'x86_64'])
 593             main.Append(CFLAGS=['-arch', 'x86_64'])
 594             main.Append(LINKFLAGS=['-arch', 'x86_64'])
 595             main.Append(ASFLAGS=['-arch', 'x86_64'])
 596 except:
 597     pass
 598
 599 # Recent versions of scons substitute a "Null" object for Configure()
 600 # when configuration isn't necessary, e.g., if the "--help" option is
 601 # present.  Unfortuantely this Null object always returns false,
 602 # breaking all our configuration checks.  We replace it with our own
 603 # more optimistic null object that returns True instead.
 604 if not conf:
 605     def NullCheck(*args, **kwargs):
 606         return True
 607
 608     class NullConf:
 609         def __init__(self, env):
 610             self.env = env
 611         def Finish(self):
 612             return self.env
 613         def __getattr__(self, mname):
 614             return NullCheck
 615
 616     conf = NullConf(main)
 617
 618 # Cache build files in the supplied directory.
 619 if main['M5_BUILD_CACHE']:
 620     print('Using build cache located at', main['M5_BUILD_CACHE'])
 621     CacheDir(main['M5_BUILD_CACHE'])
 622
 623 main['USE_PYTHON'] = not GetOption('without_python')
 624 if main['USE_PYTHON']:
 625     # Find Python include and library directories for embedding the
 626     # interpreter. We rely on python-config to resolve the appropriate
 627     # includes and linker flags. ParseConfig does not seem to understand
 628     # the more exotic linker flags such as -Xlinker and -export-dynamic so
 629     # we add them explicitly below. If you want to link in an alternate
 630     # version of python, see above for instructions on how to invoke
 631     # scons with the appropriate PATH set.
 632
 633     python_config = main.Detect(main['PYTHON_CONFIG'])
 634     if python_config is None:
 635         error("Can't find a suitable python-config, tried %s" % \
 636               main['PYTHON_CONFIG'])
 637
 638     print("Info: Using Python config: %s" % (python_config, ))
 639     py_includes = readCommand([python_config, '--includes'],
 640                               exception='').split()
 641     py_includes = list(filter(
 642         lambda s: match(r'.*\/include\/.*',s), py_includes))
 643     # Strip the -I from the include folders before adding them to the
 644     # CPPPATH
 645     py_includes = list(map(
 646         lambda s: s[2:] if s.startswith('-I') else s, py_includes))
 647     main.Append(CPPPATH=py_includes)
 648
 649     # Read the linker flags and split them into libraries and other link
 650     # flags. The libraries are added later through the call the CheckLib.
 651     # Note: starting in Python 3.8 the --embed flag is required to get the
 652     # -lpython3.8 linker flag
 653     retcode, cmd_stdout = readCommandWithReturn(
 654         [python_config, '--ldflags', '--embed'], exception='')
 655     if retcode != 0:
 656         # If --embed isn't detected then we're running python <3.8
 657         retcode, cmd_stdout = readCommandWithReturn(
 658             [python_config, '--ldflags'], exception='')
 659
 660     # Checking retcode again
 661     if retcode != 0:
 662         error("Failing on python-config --ldflags command")
 663
 664     py_ld_flags = cmd_stdout.split()
 665
 666     py_libs = []
 667     for lib in py_ld_flags:
 668          if not lib.startswith('-l'):
 669              main.Append(LINKFLAGS=[lib])
 670          else:
 671              lib = lib[2:]
 672              if lib not in py_libs:
 673                  py_libs.append(lib)
 674
 675     # verify that this stuff works
 676     if not conf.CheckHeader('Python.h', '<>'):
 677         error("Check failed for Python.h header in",
 678                 ' '.join(py_includes), "\n"
 679               "Two possible reasons:\n"
 680               "1. Python headers are not installed (You can install the "
 681               "package python-dev on Ubuntu and RedHat)\n"
 682               "2. SCons is using a wrong C compiler. This can happen if "
 683               "CC has the wrong value.\n"
 684               "CC = %s" % main['CC'])
 685
 686     for lib in py_libs:
 687         if not conf.CheckLib(lib):
 688             error("Can't find library %s required by python." % lib)
 689
 690 main.Prepend(CPPPATH=Dir('ext/pybind11/include/'))
 691 # Bare minimum environment that only includes python
 692 marshal_env = main.Clone()
 693 marshal_env.Append(CCFLAGS='$MARSHAL_CCFLAGS_EXTRA')
 694 marshal_env.Append(LINKFLAGS='$MARSHAL_LDFLAGS_EXTRA')
 695
 696 # On Solaris you need to use libsocket for socket ops
 697 if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
 698    if not conf.CheckLibWithHeader('socket', 'sys/socket.h',
 699                                   'C++', 'accept(0,0,0);'):
 700        error("Can't find library with socket calls (e.g. accept()).")
 701
 702 # Check for zlib.  If the check passes, libz will be automatically
 703 # added to the LIBS environment variable.
 704 if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
 705     error('Did not find needed zlib compression library '
 706           'and/or zlib.h header file.\n'
 707           'Please install zlib and try again.')
 708
 709 # If we have the protobuf compiler, also make sure we have the
 710 # development libraries. If the check passes, libprotobuf will be
 711 # automatically added to the LIBS environment variable. After
 712 # this, we can use the HAVE_PROTOBUF flag to determine if we have
 713 # got both protoc and libprotobuf available.
 714 main['HAVE_PROTOBUF'] = main['HAVE_PROTOC'] and \
 715     conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
 716                             'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
 717
 718 # Valgrind gets much less confused if you tell it when you're using
 719 # alternative stacks.
 720 main['HAVE_VALGRIND'] = conf.CheckCHeader('valgrind/valgrind.h')
 721
 722 # If we have the compiler but not the library, print another warning.
 723 if main['HAVE_PROTOC'] and not main['HAVE_PROTOBUF']:
 724     warning('Did not find protocol buffer library and/or headers.\n'
 725             'Please install libprotobuf-dev for tracing support.')
 726
 727 # Check for librt.
 728 have_posix_clock = \
 729     conf.CheckLibWithHeader(None, 'time.h', 'C',
 730                             'clock_nanosleep(0,0,NULL,NULL);') or \
 731     conf.CheckLibWithHeader('rt', 'time.h', 'C',
 732                             'clock_nanosleep(0,0,NULL,NULL);')
 733
 734 have_posix_timers = \
 735     conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
 736                             'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
 737
 738 if not GetOption('without_tcmalloc'):
 739     if conf.CheckLib('tcmalloc'):
 740         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 741     elif conf.CheckLib('tcmalloc_minimal'):
 742         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 743     else:
 744         warning("You can get a 12% performance improvement by "
 745                 "installing tcmalloc (libgoogle-perftools-dev package "
 746                 "on Ubuntu or RedHat).")
 747
 748
 749 # Detect back trace implementations. The last implementation in the
 750 # list will be used by default.
 751 backtrace_impls = [ "none" ]
 752
 753 backtrace_checker = 'char temp;' + \
 754     ' backtrace_symbols_fd((void*)&temp, 0, 0);'
 755 if conf.CheckLibWithHeader(None, 'execinfo.h', 'C', backtrace_checker):
 756     backtrace_impls.append("glibc")
 757 elif conf.CheckLibWithHeader('execinfo', 'execinfo.h', 'C',
 758                              backtrace_checker):
 759     # NetBSD and FreeBSD need libexecinfo.
 760     backtrace_impls.append("glibc")
 761     main.Append(LIBS=['execinfo'])
 762
 763 if backtrace_impls[-1] == "none":
 764     default_backtrace_impl = "none"
 765     warning("No suitable back trace implementation found.")
 766
 767 if not have_posix_clock:
 768     warning("Can't find library for POSIX clocks.")
 769
 770 # Check for <fenv.h> (C99 FP environment control)
 771 have_fenv = conf.CheckHeader('fenv.h', '<>')
 772 if not have_fenv:
 773     warning("Header file <fenv.h> not found.\n"
 774             "This host has no IEEE FP rounding mode control.")
 775
 776 # Check for <png.h> (libpng library needed if wanting to dump
 777 # frame buffer image in png format)
 778 have_png = conf.CheckHeader('png.h', '<>')
 779 if not have_png:
 780     warning("Header file <png.h> not found.\n"
 781             "This host has no libpng library.\n"
 782             "Disabling support for PNG framebuffers.")
 783
 784 # Check if we should enable KVM-based hardware virtualization. The API
 785 # we rely on exists since version 2.6.36 of the kernel, but somehow
 786 # the KVM_API_VERSION does not reflect the change. We test for one of
 787 # the types as a fall back.
 788 have_kvm = conf.CheckHeader('linux/kvm.h', '<>')
 789 if not have_kvm:
 790     print("Info: Compatible header file <linux/kvm.h> not found, "
 791           "disabling KVM support.")
 792
 793 # Check if the TUN/TAP driver is available.
 794 have_tuntap = conf.CheckHeader('linux/if_tun.h', '<>')
 795 if not have_tuntap:
 796     print("Info: Compatible header file <linux/if_tun.h> not found.")
 797
 798 # x86 needs support for xsave. We test for the structure here since we
 799 # won't be able to run new tests by the time we know which ISA we're
 800 # targeting.
 801 have_kvm_xsave = conf.CheckTypeSize('struct kvm_xsave',
 802                                     '#include <linux/kvm.h>') != 0
 803
 804 # Check if the requested target ISA is compatible with the host
 805 def is_isa_kvm_compatible(isa):
 806     try:
 807         import platform
 808         host_isa = platform.machine()
 809     except:
 810         warning("Failed to determine host ISA.")
 811         return False
 812
 813     if not have_posix_timers:
 814         warning("Can not enable KVM, host seems to lack support "
 815                 "for POSIX timers")
 816         return False
 817
 818     if isa == "arm":
 819         return host_isa in ( "armv7l", "aarch64" )
 820     elif isa == "x86":
 821         if host_isa != "x86_64":
 822             return False
 823
 824         if not have_kvm_xsave:
 825             warning("KVM on x86 requires xsave support in kernel headers.")
 826             return False
 827
 828         return True
 829     else:
 830         return False
 831
 832
 833 # Check if the exclude_host attribute is available. We want this to
 834 # get accurate instruction counts in KVM.
 835 main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
 836     'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
 837
 838 def check_hdf5():
 839     return \
 840         conf.CheckLibWithHeader('hdf5', 'hdf5.h', 'C',
 841                                 'H5Fcreate("", 0, 0, 0);') and \
 842         conf.CheckLibWithHeader('hdf5_cpp', 'H5Cpp.h', 'C++',
 843                                 'H5::H5File("", 0);')
 844
 845 def check_hdf5_pkg(name):
 846     print("Checking for %s using pkg-config..." % name, end="")
 847     if not have_pkg_config:
 848         print(" pkg-config not found")
 849         return False
 850
 851     try:
 852         main.ParseConfig('pkg-config --cflags-only-I --libs-only-L %s' % name)
 853         print(" yes")
 854         return True
 855     except:
 856         print(" no")
 857         return False
 858
 859 # Check if there is a pkg-config configuration for hdf5. If we find
 860 # it, setup the environment to enable linking and header inclusion. We
 861 # don't actually try to include any headers or link with hdf5 at this
 862 # stage.
 863 if not check_hdf5_pkg('hdf5-serial'):
 864     check_hdf5_pkg('hdf5')
 865
 866 # Check if the HDF5 libraries can be found. This check respects the
 867 # include path and library path provided by pkg-config. We perform
 868 # this check even if there isn't a pkg-config configuration for hdf5
 869 # since some installations don't use pkg-config.
 870 have_hdf5 = check_hdf5()
 871 if not have_hdf5:
 872     print("Warning: Couldn't find any HDF5 C++ libraries. Disabling")
 873     print("         HDF5 support.")
 874
 875 ######################################################################
 876 #
 877 # Finish the configuration
 878 #
 879 main = conf.Finish()
 880
 881 ######################################################################
 882 #
 883 # Collect all non-global variables
 884 #
 885
 886 # Define the universe of supported ISAs
 887 all_isa_list = [ ]
 888 all_gpu_isa_list = [ ]
 889 Export('all_isa_list')
 890 Export('all_gpu_isa_list')
 891
 892 class CpuModel(object):
 893     '''The CpuModel class encapsulates everything the ISA parser needs to
 894     know about a particular CPU model.'''
 895
 896     # Dict of available CPU model objects.  Accessible as CpuModel.dict.
 897     dict = {}
 898
 899     # Constructor.  Automatically adds models to CpuModel.dict.
 900     def __init__(self, name, default=False):
 901         self.name = name           # name of model
 902
 903         # This cpu is enabled by default
 904         self.default = default
 905
 906         # Add self to dict
 907         if name in CpuModel.dict:
 908             raise AttributeError("CpuModel '%s' already registered" % name)
 909         CpuModel.dict[name] = self
 910
 911 Export('CpuModel')
 912
 913 # Sticky variables get saved in the variables file so they persist from
 914 # one invocation to the next (unless overridden, in which case the new
 915 # value becomes sticky).
 916 sticky_vars = Variables(args=ARGUMENTS)
 917 Export('sticky_vars')
 918
 919 # Sticky variables that should be exported
 920 export_vars = []
 921 Export('export_vars')
 922
 923 # For Ruby
 924 all_protocols = []
 925 Export('all_protocols')
 926 protocol_dirs = []
 927 Export('protocol_dirs')
 928 slicc_includes = []
 929 Export('slicc_includes')
 930
 931 # Walk the tree and execute all SConsopts scripts that wil add to the
 932 # above variables
 933 if GetOption('verbose'):
 934     print("Reading SConsopts")
 935 for bdir in [ base_dir ] + extras_dir_list:
 936     if not isdir(bdir):
 937         error("Directory '%s' does not exist." % bdir)
 938     for root, dirs, files in os.walk(bdir):
 939         if 'SConsopts' in files:
 940             if GetOption('verbose'):
 941                 print("Reading", joinpath(root, 'SConsopts'))
 942             SConscript(joinpath(root, 'SConsopts'))
 943
 944 all_isa_list.sort()
 945 all_gpu_isa_list.sort()
 946
 947 sticky_vars.AddVariables(
 948     EnumVariable('TARGET_ISA', 'Target ISA', 'null', all_isa_list),
 949     EnumVariable('TARGET_GPU_ISA', 'Target GPU ISA', 'gcn3', all_gpu_isa_list),
 950     ListVariable('CPU_MODELS', 'CPU models',
 951                  sorted(n for n,m in CpuModel.dict.items() if m.default),
 952                  sorted(CpuModel.dict.keys())),
 953     BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
 954                  False),
 955     BoolVariable('USE_SSE2',
 956                  'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
 957                  False),
 958     BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
 959     BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
 960     BoolVariable('USE_PNG',  'Enable support for PNG images', have_png),
 961     BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models',
 962                  have_kvm),
 963     BoolVariable('USE_TUNTAP',
 964                  'Enable using a tap device to bridge to the host network',
 965                  have_tuntap),
 966     BoolVariable('BUILD_GPU', 'Build the compute-GPU model', False),
 967     EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
 968                   all_protocols),
 969     EnumVariable('BACKTRACE_IMPL', 'Post-mortem dump implementation',
 970                  backtrace_impls[-1], backtrace_impls),
 971     ('NUMBER_BITS_PER_SET', 'Max elements in set (default 64)',
 972                  64),
 973     BoolVariable('USE_HDF5', 'Enable the HDF5 support', have_hdf5),
 974     )
 975
 976 # These variables get exported to #defines in config/*.hh (see src/SConscript).
 977 export_vars += ['USE_FENV', 'TARGET_ISA', 'TARGET_GPU_ISA',
 978                 'USE_POSIX_CLOCK', 'USE_KVM', 'USE_TUNTAP', 'PROTOCOL',
 979                 'HAVE_PROTOBUF', 'HAVE_VALGRIND',
 980                 'HAVE_PERF_ATTR_EXCLUDE_HOST', 'USE_PNG',
 981                 'NUMBER_BITS_PER_SET', 'USE_HDF5']
 982
 983 ###################################################
 984 #
 985 # Define a SCons builder for configuration flag headers.
 986 #
 987 ###################################################
 988
 989 # This function generates a config header file that #defines the
 990 # variable symbol to the current variable setting (0 or 1).  The source
 991 # operands are the name of the variable and a Value node containing the
 992 # value of the variable.
 993 def build_config_file(target, source, env):
 994     (variable, value) = [s.get_contents().decode('utf-8') for s in source]
 995     with open(str(target[0]), 'w') as f:
 996         print('#define', variable, value, file=f)
 997     return None
 998
 999 # Combine the two functions into a scons Action object.
1000 config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1001
1002 # The emitter munges the source & target node lists to reflect what
1003 # we're really doing.
1004 def config_emitter(target, source, env):
1005     # extract variable name from Builder arg
1006     variable = str(target[0])
1007     # True target is config header file
1008     target = joinpath('config', variable.lower() + '.hh')
1009     val = env[variable]
1010     if isinstance(val, bool):
1011         # Force value to 0/1
1012         val = int(val)
1013     elif isinstance(val, str):
1014         val = '"' + val + '"'
1015
1016     # Sources are variable name & value (packaged in SCons Value nodes)
1017     return ([target], [Value(variable), Value(val)])
1018
1019 config_builder = Builder(emitter = config_emitter, action = config_action)
1020
1021 main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1022
1023 ###################################################
1024 #
1025 # Builders for static and shared partially linked object files.
1026 #
1027 ###################################################
1028
1029 partial_static_builder = Builder(action=SCons.Defaults.LinkAction,
1030                                  src_suffix='$OBJSUFFIX',
1031                                  src_builder=['StaticObject', 'Object'],
1032                                  LINKFLAGS='$PLINKFLAGS',
1033                                  LIBS='')
1034
1035 def partial_shared_emitter(target, source, env):
1036     for tgt in target:
1037         tgt.attributes.shared = 1
1038     return (target, source)
1039 partial_shared_builder = Builder(action=SCons.Defaults.ShLinkAction,
1040                                  emitter=partial_shared_emitter,
1041                                  src_suffix='$SHOBJSUFFIX',
1042                                  src_builder='SharedObject',
1043                                  SHLINKFLAGS='$PSHLINKFLAGS',
1044                                  LIBS='')
1045
1046 main.Append(BUILDERS = { 'PartialShared' : partial_shared_builder,
1047                          'PartialStatic' : partial_static_builder })
1048
1049 def add_local_rpath(env, *targets):
1050     '''Set up an RPATH for a library which lives in the build directory.
1051
1052     The construction environment variable BIN_RPATH_PREFIX should be set to
1053     the relative path of the build directory starting from the location of the
1054     binary.'''
1055     for target in targets:
1056         target = env.Entry(target)
1057         if not isinstance(target, SCons.Node.FS.Dir):
1058             target = target.dir
1059         relpath = os.path.relpath(target.abspath, env['BUILDDIR'])
1060         components = [
1061             '\\$$ORIGIN',
1062             '${BIN_RPATH_PREFIX}',
1063             relpath
1064         ]
1065         env.Append(RPATH=[env.Literal(os.path.join(*components))])
1066
1067 if sys.platform != "darwin":
1068     main.Append(LINKFLAGS=Split('-z origin'))
1069
1070 main.AddMethod(add_local_rpath, 'AddLocalRPATH')
1071
1072 # builds in ext are shared across all configs in the build root.
1073 ext_dir = abspath(joinpath(str(main.root), 'ext'))
1074 ext_build_dirs = []
1075 for root, dirs, files in os.walk(ext_dir):
1076     if 'SConscript' in files:
1077         build_dir = os.path.relpath(root, ext_dir)
1078         ext_build_dirs.append(build_dir)
1079         main.SConscript(joinpath(root, 'SConscript'),
1080                         variant_dir=joinpath(build_root, build_dir))
1081
1082 gdb_xml_dir = joinpath(ext_dir, 'gdb-xml')
1083 Export('gdb_xml_dir')
1084
1085 ###################################################
1086 #
1087 # This builder and wrapper method are used to set up a directory with
1088 # switching headers. Those are headers which are in a generic location and
1089 # that include more specific headers from a directory chosen at build time
1090 # based on the current build settings.
1091 #
1092 ###################################################
1093
1094 def build_switching_header(target, source, env):
1095     path = str(target[0])
1096     subdir = str(source[0])
1097     dp, fp = os.path.split(path)
1098     dp = os.path.relpath(os.path.realpath(dp),
1099                          os.path.realpath(env['BUILDDIR']))
1100     with open(path, 'w') as hdr:
1101         print('#include "%s/%s/%s"' % (dp, subdir, fp), file=hdr)
1102
1103 switching_header_action = MakeAction(build_switching_header,
1104                                      Transform('GENERATE'))
1105
1106 switching_header_builder = Builder(action=switching_header_action,
1107                                    source_factory=Value,
1108                                    single_source=True)
1109
1110 main.Append(BUILDERS = { 'SwitchingHeader': switching_header_builder })
1111
1112 def switching_headers(self, headers, source):
1113     for header in headers:
1114         self.SwitchingHeader(header, source)
1115
1116 main.AddMethod(switching_headers, 'SwitchingHeaders')
1117
1118 ###################################################
1119 #
1120 # Define build environments for selected configurations.
1121 #
1122 ###################################################
1123
1124 for variant_path in variant_paths:
1125     if not GetOption('silent'):
1126         print("Building in", variant_path)
1127
1128     # Make a copy of the build-root environment to use for this config.
1129     env = main.Clone()
1130     env['BUILDDIR'] = variant_path
1131
1132     # variant_dir is the tail component of build path, and is used to
1133     # determine the build parameters (e.g., 'X86')
1134     (build_root, variant_dir) = splitpath(variant_path)
1135
1136     # Set env variables according to the build directory config.
1137     sticky_vars.files = []
1138     # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1139     # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1140     # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1141     current_vars_file = joinpath(build_root, 'variables', variant_dir)
1142     if isfile(current_vars_file):
1143         sticky_vars.files.append(current_vars_file)
1144         if not GetOption('silent'):
1145             print("Using saved variables file %s" % current_vars_file)
1146     elif variant_dir in ext_build_dirs:
1147         # Things in ext are built without a variant directory.
1148         continue
1149     else:
1150         # Build dir-specific variables file doesn't exist.
1151
1152         # Make sure the directory is there so we can create it later
1153         opt_dir = dirname(current_vars_file)
1154         if not isdir(opt_dir):
1155             mkdir(opt_dir)
1156
1157         # Get default build variables from source tree.  Variables are
1158         # normally determined by name of $VARIANT_DIR, but can be
1159         # overridden by '--default=' arg on command line.
1160         default = GetOption('default')
1161         opts_dir = joinpath(main.root.abspath, 'build_opts')
1162         if default:
1163             default_vars_files = [joinpath(build_root, 'variables', default),
1164                                   joinpath(opts_dir, default)]
1165         else:
1166             default_vars_files = [joinpath(opts_dir, variant_dir)]
1167         existing_files = list(filter(isfile, default_vars_files))
1168         if existing_files:
1169             default_vars_file = existing_files[0]
1170             sticky_vars.files.append(default_vars_file)
1171             print("Variables file %s not found,\n  using defaults in %s"
1172                   % (current_vars_file, default_vars_file))
1173         else:
1174             error("Cannot find variables file %s or default file(s) %s"
1175                   % (current_vars_file, ' or '.join(default_vars_files)))
1176             Exit(1)
1177
1178     # Apply current variable settings to env
1179     sticky_vars.Update(env)
1180
1181     Help('''
1182 Build variables for {dir}:
1183 {help}
1184 '''.format(dir=variant_dir, help=sticky_vars.GenerateHelpText(env)),
1185          append=True)
1186
1187     # Process variable settings.
1188
1189     if not have_fenv and env['USE_FENV']:
1190         warning("<fenv.h> not available; forcing USE_FENV to False in",
1191                 variant_dir + ".")
1192         env['USE_FENV'] = False
1193
1194     if not env['USE_FENV']:
1195         warning("No IEEE FP rounding mode control in", variant_dir + ".\n"
1196                 "FP results may deviate slightly from other platforms.")
1197
1198     if not have_png and env['USE_PNG']:
1199         warning("<png.h> not available; forcing USE_PNG to False in",
1200                 variant_dir + ".")
1201         env['USE_PNG'] = False
1202
1203     if env['USE_PNG']:
1204         env.Append(LIBS=['png'])
1205
1206     if env['EFENCE']:
1207         env.Append(LIBS=['efence'])
1208
1209     if env['USE_KVM']:
1210         if not have_kvm:
1211             warning("Can not enable KVM, host seems to lack KVM support")
1212             env['USE_KVM'] = False
1213         elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1214             print("Info: KVM support disabled due to unsupported host and "
1215                   "target ISA combination")
1216             env['USE_KVM'] = False
1217
1218     if env['USE_TUNTAP']:
1219         if not have_tuntap:
1220             warning("Can't connect EtherTap with a tap device.")
1221             env['USE_TUNTAP'] = False
1222
1223     if env['BUILD_GPU']:
1224         env.Append(CPPDEFINES=['BUILD_GPU'])
1225
1226     # Warn about missing optional functionality
1227     if env['USE_KVM']:
1228         if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1229             warning("perf_event headers lack support for the exclude_host "
1230                     "attribute. KVM instruction counts will be inaccurate.")
1231
1232     # Save sticky variable settings back to current variables file
1233     sticky_vars.Save(current_vars_file, env)
1234
1235     if env['USE_SSE2']:
1236         env.Append(CCFLAGS=['-msse2'])
1237
1238     env.Append(CCFLAGS='$CCFLAGS_EXTRA')
1239     env.Append(LINKFLAGS='$LDFLAGS_EXTRA')
1240
1241     # The src/SConscript file sets up the build rules in 'env' according
1242     # to the configured variables.  It returns a list of environments,
1243     # one for each variant build (debug, opt, etc.)
1244     SConscript('src/SConscript', variant_dir=variant_path,
1245                exports=['env', 'marshal_env'])
1246
1247 atexit.register(summarize_warnings)