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