SConstruct

   1 # -*- mode:python -*-
   2
   3 # Copyright (c) 2013, 2015-2017 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 # Authors: Steve Reinhardt
  44 #          Nathan Binkert
  45
  46 ###################################################
  47 #
  48 # SCons top-level build description (SConstruct) file.
  49 #
  50 # While in this directory ('gem5'), just type 'scons' to build the default
  51 # configuration (see below), or type 'scons build/<CONFIG>/<binary>'
  52 # to build some other configuration (e.g., 'build/ALPHA/gem5.opt' for
  53 # the optimized full-system version).
  54 #
  55 # You can build gem5 in a different directory as long as there is a
  56 # 'build/<CONFIG>' somewhere along the target path.  The build system
  57 # expects that all configs under the same build directory are being
  58 # built for the same host system.
  59 #
  60 # Examples:
  61 #
  62 #   The following two commands are equivalent.  The '-u' option tells
  63 #   scons to search up the directory tree for this SConstruct file.
  64 #   % cd <path-to-src>/gem5 ; scons build/ALPHA/gem5.debug
  65 #   % cd <path-to-src>/gem5/build/ALPHA; scons -u gem5.debug
  66 #
  67 #   The following two commands are equivalent and demonstrate building
  68 #   in a directory outside of the source tree.  The '-C' option tells
  69 #   scons to chdir to the specified directory to find this SConstruct
  70 #   file.
  71 #   % cd <path-to-src>/gem5 ; scons /local/foo/build/ALPHA/gem5.debug
  72 #   % cd /local/foo/build/ALPHA; scons -C <path-to-src>/gem5 gem5.debug
  73 #
  74 # You can use 'scons -H' to print scons options.  If you're in this
  75 # 'gem5' directory (or use -u or -C to tell scons where to find this
  76 # file), you can use 'scons -h' to print all the gem5-specific build
  77 # options as well.
  78 #
  79 ###################################################
  80
  81 # Global Python includes
  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
  94 # SCons includes
  95 import SCons
  96 import SCons.Node
  97
  98 from m5.util import compareVersions, readCommand
  99
 100 help_texts = {
 101     "options" : "",
 102     "global_vars" : "",
 103     "local_vars" : ""
 104 }
 105
 106 Export("help_texts")
 107
 108
 109 # There's a bug in scons in that (1) by default, the help texts from
 110 # AddOption() are supposed to be displayed when you type 'scons -h'
 111 # and (2) you can override the help displayed by 'scons -h' using the
 112 # Help() function, but these two features are incompatible: once
 113 # you've overridden the help text using Help(), there's no way to get
 114 # at the help texts from AddOptions.  See:
 115 #     http://scons.tigris.org/issues/show_bug.cgi?id=2356
 116 #     http://scons.tigris.org/issues/show_bug.cgi?id=2611
 117 # This hack lets us extract the help text from AddOptions and
 118 # re-inject it via Help().  Ideally someday this bug will be fixed and
 119 # we can just use AddOption directly.
 120 def AddLocalOption(*args, **kwargs):
 121     col_width = 30
 122
 123     help = "  " + ", ".join(args)
 124     if "help" in kwargs:
 125         length = len(help)
 126         if length >= col_width:
 127             help += "\n" + " " * col_width
 128         else:
 129             help += " " * (col_width - length)
 130         help += kwargs["help"]
 131     help_texts["options"] += help + "\n"
 132
 133     AddOption(*args, **kwargs)
 134
 135 AddLocalOption('--colors', dest='use_colors', action='store_true',
 136                help="Add color to abbreviated scons output")
 137 AddLocalOption('--no-colors', dest='use_colors', action='store_false',
 138                help="Don't add color to abbreviated scons output")
 139 AddLocalOption('--with-cxx-config', dest='with_cxx_config',
 140                action='store_true',
 141                help="Build with support for C++-based configuration")
 142 AddLocalOption('--default', dest='default', type='string', action='store',
 143                help='Override which build_opts file to use for defaults')
 144 AddLocalOption('--ignore-style', dest='ignore_style', action='store_true',
 145                help='Disable style checking hooks')
 146 AddLocalOption('--no-lto', dest='no_lto', action='store_true',
 147                help='Disable Link-Time Optimization for fast')
 148 AddLocalOption('--force-lto', dest='force_lto', action='store_true',
 149                help='Use Link-Time Optimization instead of partial linking' +
 150                     ' when the compiler doesn\'t support using them together.')
 151 AddLocalOption('--update-ref', dest='update_ref', action='store_true',
 152                help='Update test reference outputs')
 153 AddLocalOption('--verbose', dest='verbose', action='store_true',
 154                help='Print full tool command lines')
 155 AddLocalOption('--without-python', dest='without_python',
 156                action='store_true',
 157                help='Build without Python configuration support')
 158 AddLocalOption('--without-tcmalloc', dest='without_tcmalloc',
 159                action='store_true',
 160                help='Disable linking against tcmalloc')
 161 AddLocalOption('--with-ubsan', dest='with_ubsan', action='store_true',
 162                help='Build with Undefined Behavior Sanitizer if available')
 163 AddLocalOption('--with-asan', dest='with_asan', action='store_true',
 164                help='Build with Address Sanitizer if available')
 165
 166 if GetOption('no_lto') and GetOption('force_lto'):
 167     print '--no-lto and --force-lto are mutually exclusive'
 168     Exit(1)
 169
 170 ########################################################################
 171 #
 172 # Set up the main build environment.
 173 #
 174 ########################################################################
 175
 176 main = Environment()
 177
 178 from gem5_scons import Transform
 179 from gem5_scons.util import get_termcap
 180 termcap = get_termcap()
 181
 182 main_dict_keys = main.Dictionary().keys()
 183
 184 # Check that we have a C/C++ compiler
 185 if not ('CC' in main_dict_keys and 'CXX' in main_dict_keys):
 186     print "No C++ compiler installed (package g++ on Ubuntu and RedHat)"
 187     Exit(1)
 188
 189 ###################################################
 190 #
 191 # Figure out which configurations to set up based on the path(s) of
 192 # the target(s).
 193 #
 194 ###################################################
 195
 196 # Find default configuration & binary.
 197 Default(environ.get('M5_DEFAULT_BINARY', 'build/ALPHA/gem5.debug'))
 198
 199 # helper function: find last occurrence of element in list
 200 def rfind(l, elt, offs = -1):
 201     for i in range(len(l)+offs, 0, -1):
 202         if l[i] == elt:
 203             return i
 204     raise ValueError, "element not found"
 205
 206 # Take a list of paths (or SCons Nodes) and return a list with all
 207 # paths made absolute and ~-expanded.  Paths will be interpreted
 208 # relative to the launch directory unless a different root is provided
 209 def makePathListAbsolute(path_list, root=GetLaunchDir()):
 210     return [abspath(joinpath(root, expanduser(str(p))))
 211             for p in path_list]
 212
 213 # Each target must have 'build' in the interior of the path; the
 214 # directory below this will determine the build parameters.  For
 215 # example, for target 'foo/bar/build/ALPHA_SE/arch/alpha/blah.do' we
 216 # recognize that ALPHA_SE specifies the configuration because it
 217 # follow 'build' in the build path.
 218
 219 # The funky assignment to "[:]" is needed to replace the list contents
 220 # in place rather than reassign the symbol to a new list, which
 221 # doesn't work (obviously!).
 222 BUILD_TARGETS[:] = makePathListAbsolute(BUILD_TARGETS)
 223
 224 # Generate a list of the unique build roots and configs that the
 225 # collected targets reference.
 226 variant_paths = []
 227 build_root = None
 228 for t in BUILD_TARGETS:
 229     path_dirs = t.split('/')
 230     try:
 231         build_top = rfind(path_dirs, 'build', -2)
 232     except:
 233         print "Error: no non-leaf 'build' dir found on target path", t
 234         Exit(1)
 235     this_build_root = joinpath('/',*path_dirs[:build_top+1])
 236     if not build_root:
 237         build_root = this_build_root
 238     else:
 239         if this_build_root != build_root:
 240             print "Error: build targets not under same build root\n"\
 241                   "  %s\n  %s" % (build_root, this_build_root)
 242             Exit(1)
 243     variant_path = joinpath('/',*path_dirs[:build_top+2])
 244     if variant_path not in variant_paths:
 245         variant_paths.append(variant_path)
 246
 247 # Make sure build_root exists (might not if this is the first build there)
 248 if not isdir(build_root):
 249     mkdir(build_root)
 250 main['BUILDROOT'] = build_root
 251
 252 Export('main')
 253
 254 main.SConsignFile(joinpath(build_root, "sconsign"))
 255
 256 # Default duplicate option is to use hard links, but this messes up
 257 # when you use emacs to edit a file in the target dir, as emacs moves
 258 # file to file~ then copies to file, breaking the link.  Symbolic
 259 # (soft) links work better.
 260 main.SetOption('duplicate', 'soft-copy')
 261
 262 #
 263 # Set up global sticky variables... these are common to an entire build
 264 # tree (not specific to a particular build like ALPHA_SE)
 265 #
 266
 267 global_vars_file = joinpath(build_root, 'variables.global')
 268
 269 global_vars = Variables(global_vars_file, args=ARGUMENTS)
 270
 271 global_vars.AddVariables(
 272     ('CC', 'C compiler', environ.get('CC', main['CC'])),
 273     ('CXX', 'C++ compiler', environ.get('CXX', main['CXX'])),
 274     ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
 275     ('BATCH', 'Use batch pool for build and tests', False),
 276     ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
 277     ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
 278     ('EXTRAS', 'Add extra directories to the compilation', '')
 279     )
 280
 281 # Update main environment with values from ARGUMENTS & global_vars_file
 282 global_vars.Update(main)
 283 help_texts["global_vars"] += global_vars.GenerateHelpText(main)
 284
 285 # Save sticky variable settings back to current variables file
 286 global_vars.Save(global_vars_file, main)
 287
 288 # Parse EXTRAS variable to build list of all directories where we're
 289 # look for sources etc.  This list is exported as extras_dir_list.
 290 base_dir = main.srcdir.abspath
 291 if main['EXTRAS']:
 292     extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
 293 else:
 294     extras_dir_list = []
 295
 296 Export('base_dir')
 297 Export('extras_dir_list')
 298
 299 # the ext directory should be on the #includes path
 300 main.Append(CPPPATH=[Dir('ext')])
 301
 302 # Add shared top-level headers
 303 main.Prepend(CPPPATH=Dir('include'))
 304
 305 if GetOption('verbose'):
 306     def MakeAction(action, string, *args, **kwargs):
 307         return Action(action, *args, **kwargs)
 308 else:
 309     MakeAction = Action
 310     main['CCCOMSTR']        = Transform("CC")
 311     main['CXXCOMSTR']       = Transform("CXX")
 312     main['ASCOMSTR']        = Transform("AS")
 313     main['ARCOMSTR']        = Transform("AR", 0)
 314     main['LINKCOMSTR']      = Transform("LINK", 0)
 315     main['SHLINKCOMSTR']    = Transform("SHLINK", 0)
 316     main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
 317     main['M4COMSTR']        = Transform("M4")
 318     main['SHCCCOMSTR']      = Transform("SHCC")
 319     main['SHCXXCOMSTR']     = Transform("SHCXX")
 320 Export('MakeAction')
 321
 322 # Initialize the Link-Time Optimization (LTO) flags
 323 main['LTO_CCFLAGS'] = []
 324 main['LTO_LDFLAGS'] = []
 325
 326 # According to the readme, tcmalloc works best if the compiler doesn't
 327 # assume that we're using the builtin malloc and friends. These flags
 328 # are compiler-specific, so we need to set them after we detect which
 329 # compiler we're using.
 330 main['TCMALLOC_CCFLAGS'] = []
 331
 332 CXX_version = readCommand([main['CXX'],'--version'], exception=False)
 333 CXX_V = readCommand([main['CXX'],'-V'], exception=False)
 334
 335 main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
 336 main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
 337 if main['GCC'] + main['CLANG'] > 1:
 338     print 'Error: How can we have two at the same time?'
 339     Exit(1)
 340
 341 # Set up default C++ compiler flags
 342 if main['GCC'] or main['CLANG']:
 343     # As gcc and clang share many flags, do the common parts here
 344     main.Append(CCFLAGS=['-pipe'])
 345     main.Append(CCFLAGS=['-fno-strict-aliasing'])
 346     # Enable -Wall and -Wextra and then disable the few warnings that
 347     # we consistently violate
 348     main.Append(CCFLAGS=['-Wall', '-Wundef', '-Wextra',
 349                          '-Wno-sign-compare', '-Wno-unused-parameter'])
 350     # We always compile using C++11
 351     main.Append(CXXFLAGS=['-std=c++11'])
 352     if sys.platform.startswith('freebsd'):
 353         main.Append(CCFLAGS=['-I/usr/local/include'])
 354         main.Append(CXXFLAGS=['-I/usr/local/include'])
 355
 356     main['FILTER_PSHLINKFLAGS'] = lambda x: str(x).replace(' -shared', '')
 357     main['PSHLINKFLAGS'] = main.subst('${FILTER_PSHLINKFLAGS(SHLINKFLAGS)}')
 358     main['PLINKFLAGS'] = main.subst('${LINKFLAGS}')
 359     shared_partial_flags = ['-r', '-nostdlib']
 360     main.Append(PSHLINKFLAGS=shared_partial_flags)
 361     main.Append(PLINKFLAGS=shared_partial_flags)
 362 else:
 363     print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
 364     print "Don't know what compiler options to use for your compiler."
 365     print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
 366     print termcap.Yellow + '       version:' + termcap.Normal,
 367     if not CXX_version:
 368         print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
 369                termcap.Normal
 370     else:
 371         print CXX_version.replace('\n', '<nl>')
 372     print "       If you're trying to use a compiler other than GCC"
 373     print "       or clang, there appears to be something wrong with your"
 374     print "       environment."
 375     print "       "
 376     print "       If you are trying to use a compiler other than those listed"
 377     print "       above you will need to ease fix SConstruct and "
 378     print "       src/SConscript to support that compiler."
 379     Exit(1)
 380
 381 if main['GCC']:
 382     # Check for a supported version of gcc. >= 4.8 is chosen for its
 383     # level of c++11 support. See
 384     # http://gcc.gnu.org/projects/cxx0x.html for details.
 385     gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
 386     if compareVersions(gcc_version, "4.8") < 0:
 387         print 'Error: gcc version 4.8 or newer required.'
 388         print '       Installed version:', gcc_version
 389         Exit(1)
 390
 391     main['GCC_VERSION'] = gcc_version
 392
 393     if compareVersions(gcc_version, '4.9') >= 0:
 394         # Incremental linking with LTO is currently broken in gcc versions
 395         # 4.9 and above. A version where everything works completely hasn't
 396         # yet been identified.
 397         #
 398         # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67548
 399         main['BROKEN_INCREMENTAL_LTO'] = True
 400     if compareVersions(gcc_version, '6.0') >= 0:
 401         # gcc versions 6.0 and greater accept an -flinker-output flag which
 402         # selects what type of output the linker should generate. This is
 403         # necessary for incremental lto to work, but is also broken in
 404         # current versions of gcc. It may not be necessary in future
 405         # versions. We add it here since it might be, and as a reminder that
 406         # it exists. It's excluded if lto is being forced.
 407         #
 408         # https://gcc.gnu.org/gcc-6/changes.html
 409         # https://gcc.gnu.org/ml/gcc-patches/2015-11/msg03161.html
 410         # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69866
 411         if not GetOption('force_lto'):
 412             main.Append(PSHLINKFLAGS='-flinker-output=rel')
 413             main.Append(PLINKFLAGS='-flinker-output=rel')
 414
 415     # gcc from version 4.8 and above generates "rep; ret" instructions
 416     # to avoid performance penalties on certain AMD chips. Older
 417     # assemblers detect this as an error, "Error: expecting string
 418     # instruction after `rep'"
 419     as_version_raw = readCommand([main['AS'], '-v', '/dev/null',
 420                                   '-o', '/dev/null'],
 421                                  exception=False).split()
 422
 423     # version strings may contain extra distro-specific
 424     # qualifiers, so play it safe and keep only what comes before
 425     # the first hyphen
 426     as_version = as_version_raw[-1].split('-')[0] if as_version_raw else None
 427
 428     if not as_version or compareVersions(as_version, "2.23") < 0:
 429         print termcap.Yellow + termcap.Bold + \
 430             'Warning: This combination of gcc and binutils have' + \
 431             ' known incompatibilities.\n' + \
 432             '         If you encounter build problems, please update ' + \
 433             'binutils to 2.23.' + \
 434             termcap.Normal
 435
 436     # Make sure we warn if the user has requested to compile with the
 437     # Undefined Benahvior Sanitizer and this version of gcc does not
 438     # support it.
 439     if GetOption('with_ubsan') and \
 440             compareVersions(gcc_version, '4.9') < 0:
 441         print termcap.Yellow + termcap.Bold + \
 442             'Warning: UBSan is only supported using gcc 4.9 and later.' + \
 443             termcap.Normal
 444
 445     disable_lto = GetOption('no_lto')
 446     if not disable_lto and main.get('BROKEN_INCREMENTAL_LTO', False) and \
 447             not GetOption('force_lto'):
 448         print termcap.Yellow + termcap.Bold + \
 449             'Warning: Your compiler doesn\'t support incremental linking' + \
 450             ' and lto at the same time, so lto is being disabled. To force' + \
 451             ' lto on anyway, use the --force-lto option. That will disable' + \
 452             ' partial linking.' + \
 453             termcap.Normal
 454         disable_lto = True
 455
 456     # Add the appropriate Link-Time Optimization (LTO) flags
 457     # unless LTO is explicitly turned off. Note that these flags
 458     # are only used by the fast target.
 459     if not disable_lto:
 460         # Pass the LTO flag when compiling to produce GIMPLE
 461         # output, we merely create the flags here and only append
 462         # them later
 463         main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 464
 465         # Use the same amount of jobs for LTO as we are running
 466         # scons with
 467         main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
 468
 469     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
 470                                   '-fno-builtin-realloc', '-fno-builtin-free'])
 471
 472     # add option to check for undeclared overrides
 473     if compareVersions(gcc_version, "5.0") > 0:
 474         main.Append(CCFLAGS=['-Wno-error=suggest-override'])
 475
 476 elif main['CLANG']:
 477     # Check for a supported version of clang, >= 3.1 is needed to
 478     # support similar features as gcc 4.8. See
 479     # http://clang.llvm.org/cxx_status.html for details
 480     clang_version_re = re.compile(".* version (\d+\.\d+)")
 481     clang_version_match = clang_version_re.search(CXX_version)
 482     if (clang_version_match):
 483         clang_version = clang_version_match.groups()[0]
 484         if compareVersions(clang_version, "3.1") < 0:
 485             print 'Error: clang version 3.1 or newer required.'
 486             print '       Installed version:', clang_version
 487             Exit(1)
 488     else:
 489         print 'Error: Unable to determine clang version.'
 490         Exit(1)
 491
 492     # clang has a few additional warnings that we disable, extraneous
 493     # parantheses are allowed due to Ruby's printing of the AST,
 494     # finally self assignments are allowed as the generated CPU code
 495     # is relying on this
 496     main.Append(CCFLAGS=['-Wno-parentheses',
 497                          '-Wno-self-assign',
 498                          # Some versions of libstdc++ (4.8?) seem to
 499                          # use struct hash and class hash
 500                          # interchangeably.
 501                          '-Wno-mismatched-tags',
 502                          ])
 503
 504     main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
 505
 506     # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
 507     # opposed to libstdc++, as the later is dated.
 508     if sys.platform == "darwin":
 509         main.Append(CXXFLAGS=['-stdlib=libc++'])
 510         main.Append(LIBS=['c++'])
 511
 512     # On FreeBSD we need libthr.
 513     if sys.platform.startswith('freebsd'):
 514         main.Append(LIBS=['thr'])
 515
 516 else:
 517     print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
 518     print "Don't know what compiler options to use for your compiler."
 519     print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
 520     print termcap.Yellow + '       version:' + termcap.Normal,
 521     if not CXX_version:
 522         print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
 523                termcap.Normal
 524     else:
 525         print CXX_version.replace('\n', '<nl>')
 526     print "       If you're trying to use a compiler other than GCC"
 527     print "       or clang, there appears to be something wrong with your"
 528     print "       environment."
 529     print "       "
 530     print "       If you are trying to use a compiler other than those listed"
 531     print "       above you will need to ease fix SConstruct and "
 532     print "       src/SConscript to support that compiler."
 533     Exit(1)
 534
 535 # Set up common yacc/bison flags (needed for Ruby)
 536 main['YACCFLAGS'] = '-d'
 537 main['YACCHXXFILESUFFIX'] = '.hh'
 538
 539 # Do this after we save setting back, or else we'll tack on an
 540 # extra 'qdo' every time we run scons.
 541 if main['BATCH']:
 542     main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
 543     main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
 544     main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
 545     main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
 546     main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
 547
 548 if sys.platform == 'cygwin':
 549     # cygwin has some header file issues...
 550     main.Append(CCFLAGS=["-Wno-uninitialized"])
 551
 552 # Check for the protobuf compiler
 553 protoc_version = readCommand([main['PROTOC'], '--version'],
 554                              exception='').split()
 555
 556 # First two words should be "libprotoc x.y.z"
 557 if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
 558     print termcap.Yellow + termcap.Bold + \
 559         'Warning: Protocol buffer compiler (protoc) not found.\n' + \
 560         '         Please install protobuf-compiler for tracing support.' + \
 561         termcap.Normal
 562     main['PROTOC'] = False
 563 else:
 564     # Based on the availability of the compress stream wrappers,
 565     # require 2.1.0
 566     min_protoc_version = '2.1.0'
 567     if compareVersions(protoc_version[1], min_protoc_version) < 0:
 568         print termcap.Yellow + termcap.Bold + \
 569             'Warning: protoc version', min_protoc_version, \
 570             'or newer required.\n' + \
 571             '         Installed version:', protoc_version[1], \
 572             termcap.Normal
 573         main['PROTOC'] = False
 574     else:
 575         # Attempt to determine the appropriate include path and
 576         # library path using pkg-config, that means we also need to
 577         # check for pkg-config. Note that it is possible to use
 578         # protobuf without the involvement of pkg-config. Later on we
 579         # check go a library config check and at that point the test
 580         # will fail if libprotobuf cannot be found.
 581         if readCommand(['pkg-config', '--version'], exception=''):
 582             try:
 583                 # Attempt to establish what linking flags to add for protobuf
 584                 # using pkg-config
 585                 main.ParseConfig('pkg-config --cflags --libs-only-L protobuf')
 586             except:
 587                 print termcap.Yellow + termcap.Bold + \
 588                     'Warning: pkg-config could not get protobuf flags.' + \
 589                     termcap.Normal
 590
 591
 592 # Check for 'timeout' from GNU coreutils. If present, regressions will
 593 # be run with a time limit. We require version 8.13 since we rely on
 594 # support for the '--foreground' option.
 595 if sys.platform.startswith('freebsd'):
 596     timeout_lines = readCommand(['gtimeout', '--version'],
 597                                 exception='').splitlines()
 598 else:
 599     timeout_lines = readCommand(['timeout', '--version'],
 600                                 exception='').splitlines()
 601 # Get the first line and tokenize it
 602 timeout_version = timeout_lines[0].split() if timeout_lines else []
 603 main['TIMEOUT'] =  timeout_version and \
 604     compareVersions(timeout_version[-1], '8.13') >= 0
 605
 606 # Add a custom Check function to test for structure members.
 607 def CheckMember(context, include, decl, member, include_quotes="<>"):
 608     context.Message("Checking for member %s in %s..." %
 609                     (member, decl))
 610     text = """
 611 #include %(header)s
 612 int main(){
 613   %(decl)s test;
 614   (void)test.%(member)s;
 615   return 0;
 616 };
 617 """ % { "header" : include_quotes[0] + include + include_quotes[1],
 618         "decl" : decl,
 619         "member" : member,
 620         }
 621
 622     ret = context.TryCompile(text, extension=".cc")
 623     context.Result(ret)
 624     return ret
 625
 626 # Platform-specific configuration.  Note again that we assume that all
 627 # builds under a given build root run on the same host platform.
 628 conf = Configure(main,
 629                  conf_dir = joinpath(build_root, '.scons_config'),
 630                  log_file = joinpath(build_root, 'scons_config.log'),
 631                  custom_tests = {
 632         'CheckMember' : CheckMember,
 633         })
 634
 635 # Check if we should compile a 64 bit binary on Mac OS X/Darwin
 636 try:
 637     import platform
 638     uname = platform.uname()
 639     if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
 640         if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
 641             main.Append(CCFLAGS=['-arch', 'x86_64'])
 642             main.Append(CFLAGS=['-arch', 'x86_64'])
 643             main.Append(LINKFLAGS=['-arch', 'x86_64'])
 644             main.Append(ASFLAGS=['-arch', 'x86_64'])
 645 except:
 646     pass
 647
 648 # Recent versions of scons substitute a "Null" object for Configure()
 649 # when configuration isn't necessary, e.g., if the "--help" option is
 650 # present.  Unfortuantely this Null object always returns false,
 651 # breaking all our configuration checks.  We replace it with our own
 652 # more optimistic null object that returns True instead.
 653 if not conf:
 654     def NullCheck(*args, **kwargs):
 655         return True
 656
 657     class NullConf:
 658         def __init__(self, env):
 659             self.env = env
 660         def Finish(self):
 661             return self.env
 662         def __getattr__(self, mname):
 663             return NullCheck
 664
 665     conf = NullConf(main)
 666
 667 # Cache build files in the supplied directory.
 668 if main['M5_BUILD_CACHE']:
 669     print 'Using build cache located at', main['M5_BUILD_CACHE']
 670     CacheDir(main['M5_BUILD_CACHE'])
 671
 672 main['USE_PYTHON'] = not GetOption('without_python')
 673 if main['USE_PYTHON']:
 674     # Find Python include and library directories for embedding the
 675     # interpreter. We rely on python-config to resolve the appropriate
 676     # includes and linker flags. ParseConfig does not seem to understand
 677     # the more exotic linker flags such as -Xlinker and -export-dynamic so
 678     # we add them explicitly below. If you want to link in an alternate
 679     # version of python, see above for instructions on how to invoke
 680     # scons with the appropriate PATH set.
 681     #
 682     # First we check if python2-config exists, else we use python-config
 683     python_config = readCommand(['which', 'python2-config'],
 684                                 exception='').strip()
 685     if not os.path.exists(python_config):
 686         python_config = readCommand(['which', 'python-config'],
 687                                     exception='').strip()
 688     py_includes = readCommand([python_config, '--includes'],
 689                               exception='').split()
 690     # Strip the -I from the include folders before adding them to the
 691     # CPPPATH
 692     main.Append(CPPPATH=map(lambda inc: inc[2:], py_includes))
 693
 694     # Read the linker flags and split them into libraries and other link
 695     # flags. The libraries are added later through the call the CheckLib.
 696     py_ld_flags = readCommand([python_config, '--ldflags'],
 697         exception='').split()
 698     py_libs = []
 699     for lib in py_ld_flags:
 700          if not lib.startswith('-l'):
 701              main.Append(LINKFLAGS=[lib])
 702          else:
 703              lib = lib[2:]
 704              if lib not in py_libs:
 705                  py_libs.append(lib)
 706
 707     # verify that this stuff works
 708     if not conf.CheckHeader('Python.h', '<>'):
 709         print "Error: can't find Python.h header in", py_includes
 710         print "Install Python headers (package python-dev on Ubuntu and RedHat)"
 711         Exit(1)
 712
 713     for lib in py_libs:
 714         if not conf.CheckLib(lib):
 715             print "Error: can't find library %s required by python" % lib
 716             Exit(1)
 717
 718 # On Solaris you need to use libsocket for socket ops
 719 if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
 720    if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
 721        print "Can't find library with socket calls (e.g. accept())"
 722        Exit(1)
 723
 724 # Check for zlib.  If the check passes, libz will be automatically
 725 # added to the LIBS environment variable.
 726 if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
 727     print 'Error: did not find needed zlib compression library '\
 728           'and/or zlib.h header file.'
 729     print '       Please install zlib and try again.'
 730     Exit(1)
 731
 732 # If we have the protobuf compiler, also make sure we have the
 733 # development libraries. If the check passes, libprotobuf will be
 734 # automatically added to the LIBS environment variable. After
 735 # this, we can use the HAVE_PROTOBUF flag to determine if we have
 736 # got both protoc and libprotobuf available.
 737 main['HAVE_PROTOBUF'] = main['PROTOC'] and \
 738     conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
 739                             'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
 740
 741 # If we have the compiler but not the library, print another warning.
 742 if main['PROTOC'] and not main['HAVE_PROTOBUF']:
 743     print termcap.Yellow + termcap.Bold + \
 744         'Warning: did not find protocol buffer library and/or headers.\n' + \
 745     '       Please install libprotobuf-dev for tracing support.' + \
 746     termcap.Normal
 747
 748 # Check for librt.
 749 have_posix_clock = \
 750     conf.CheckLibWithHeader(None, 'time.h', 'C',
 751                             'clock_nanosleep(0,0,NULL,NULL);') or \
 752     conf.CheckLibWithHeader('rt', 'time.h', 'C',
 753                             'clock_nanosleep(0,0,NULL,NULL);')
 754
 755 have_posix_timers = \
 756     conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
 757                             'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
 758
 759 if not GetOption('without_tcmalloc'):
 760     if conf.CheckLib('tcmalloc'):
 761         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 762     elif conf.CheckLib('tcmalloc_minimal'):
 763         main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
 764     else:
 765         print termcap.Yellow + termcap.Bold + \
 766               "You can get a 12% performance improvement by "\
 767               "installing tcmalloc (libgoogle-perftools-dev package "\
 768               "on Ubuntu or RedHat)." + termcap.Normal
 769
 770
 771 # Detect back trace implementations. The last implementation in the
 772 # list will be used by default.
 773 backtrace_impls = [ "none" ]
 774
 775 if conf.CheckLibWithHeader(None, 'execinfo.h', 'C',
 776                            'backtrace_symbols_fd((void*)0, 0, 0);'):
 777     backtrace_impls.append("glibc")
 778 elif conf.CheckLibWithHeader('execinfo', 'execinfo.h', 'C',
 779                            'backtrace_symbols_fd((void*)0, 0, 0);'):
 780     # NetBSD and FreeBSD need libexecinfo.
 781     backtrace_impls.append("glibc")
 782     main.Append(LIBS=['execinfo'])
 783
 784 if backtrace_impls[-1] == "none":
 785     default_backtrace_impl = "none"
 786     print termcap.Yellow + termcap.Bold + \
 787         "No suitable back trace implementation found." + \
 788         termcap.Normal
 789
 790 if not have_posix_clock:
 791     print "Can't find library for POSIX clocks."
 792
 793 # Check for <fenv.h> (C99 FP environment control)
 794 have_fenv = conf.CheckHeader('fenv.h', '<>')
 795 if not have_fenv:
 796     print "Warning: Header file <fenv.h> not found."
 797     print "         This host has no IEEE FP rounding mode control."
 798
 799 # Check for <png.h> (libpng library needed if wanting to dump
 800 # frame buffer image in png format)
 801 have_png = conf.CheckHeader('png.h', '<>')
 802 if not have_png:
 803     print "Warning: Header file <png.h> not found."
 804     print "         This host has no libpng library."
 805     print "         Disabling support for PNG framebuffers."
 806
 807 # Check if we should enable KVM-based hardware virtualization. The API
 808 # we rely on exists since version 2.6.36 of the kernel, but somehow
 809 # the KVM_API_VERSION does not reflect the change. We test for one of
 810 # the types as a fall back.
 811 have_kvm = conf.CheckHeader('linux/kvm.h', '<>')
 812 if not have_kvm:
 813     print "Info: Compatible header file <linux/kvm.h> not found, " \
 814         "disabling KVM support."
 815
 816 # Check if the TUN/TAP driver is available.
 817 have_tuntap = conf.CheckHeader('linux/if_tun.h', '<>')
 818 if not have_tuntap:
 819     print "Info: Compatible header file <linux/if_tun.h> not found."
 820
 821 # x86 needs support for xsave. We test for the structure here since we
 822 # won't be able to run new tests by the time we know which ISA we're
 823 # targeting.
 824 have_kvm_xsave = conf.CheckTypeSize('struct kvm_xsave',
 825                                     '#include <linux/kvm.h>') != 0
 826
 827 # Check if the requested target ISA is compatible with the host
 828 def is_isa_kvm_compatible(isa):
 829     try:
 830         import platform
 831         host_isa = platform.machine()
 832     except:
 833         print "Warning: Failed to determine host ISA."
 834         return False
 835
 836     if not have_posix_timers:
 837         print "Warning: Can not enable KVM, host seems to lack support " \
 838             "for POSIX timers"
 839         return False
 840
 841     if isa == "arm":
 842         return host_isa in ( "armv7l", "aarch64" )
 843     elif isa == "x86":
 844         if host_isa != "x86_64":
 845             return False
 846
 847         if not have_kvm_xsave:
 848             print "KVM on x86 requires xsave support in kernel headers."
 849             return False
 850
 851         return True
 852     else:
 853         return False
 854
 855
 856 # Check if the exclude_host attribute is available. We want this to
 857 # get accurate instruction counts in KVM.
 858 main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
 859     'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
 860
 861
 862 ######################################################################
 863 #
 864 # Finish the configuration
 865 #
 866 main = conf.Finish()
 867
 868 ######################################################################
 869 #
 870 # Collect all non-global variables
 871 #
 872
 873 # Define the universe of supported ISAs
 874 all_isa_list = [ ]
 875 all_gpu_isa_list = [ ]
 876 Export('all_isa_list')
 877 Export('all_gpu_isa_list')
 878
 879 class CpuModel(object):
 880     '''The CpuModel class encapsulates everything the ISA parser needs to
 881     know about a particular CPU model.'''
 882
 883     # Dict of available CPU model objects.  Accessible as CpuModel.dict.
 884     dict = {}
 885
 886     # Constructor.  Automatically adds models to CpuModel.dict.
 887     def __init__(self, name, default=False):
 888         self.name = name           # name of model
 889
 890         # This cpu is enabled by default
 891         self.default = default
 892
 893         # Add self to dict
 894         if name in CpuModel.dict:
 895             raise AttributeError, "CpuModel '%s' already registered" % name
 896         CpuModel.dict[name] = self
 897
 898 Export('CpuModel')
 899
 900 # Sticky variables get saved in the variables file so they persist from
 901 # one invocation to the next (unless overridden, in which case the new
 902 # value becomes sticky).
 903 sticky_vars = Variables(args=ARGUMENTS)
 904 Export('sticky_vars')
 905
 906 # Sticky variables that should be exported
 907 export_vars = []
 908 Export('export_vars')
 909
 910 # For Ruby
 911 all_protocols = []
 912 Export('all_protocols')
 913 protocol_dirs = []
 914 Export('protocol_dirs')
 915 slicc_includes = []
 916 Export('slicc_includes')
 917
 918 # Walk the tree and execute all SConsopts scripts that wil add to the
 919 # above variables
 920 if GetOption('verbose'):
 921     print "Reading SConsopts"
 922 for bdir in [ base_dir ] + extras_dir_list:
 923     if not isdir(bdir):
 924         print "Error: directory '%s' does not exist" % bdir
 925         Exit(1)
 926     for root, dirs, files in os.walk(bdir):
 927         if 'SConsopts' in files:
 928             if GetOption('verbose'):
 929                 print "Reading", joinpath(root, 'SConsopts')
 930             SConscript(joinpath(root, 'SConsopts'))
 931
 932 all_isa_list.sort()
 933 all_gpu_isa_list.sort()
 934
 935 sticky_vars.AddVariables(
 936     EnumVariable('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
 937     EnumVariable('TARGET_GPU_ISA', 'Target GPU ISA', 'hsail', all_gpu_isa_list),
 938     ListVariable('CPU_MODELS', 'CPU models',
 939                  sorted(n for n,m in CpuModel.dict.iteritems() if m.default),
 940                  sorted(CpuModel.dict.keys())),
 941     BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
 942                  False),
 943     BoolVariable('SS_COMPATIBLE_FP',
 944                  'Make floating-point results compatible with SimpleScalar',
 945                  False),
 946     BoolVariable('USE_SSE2',
 947                  'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
 948                  False),
 949     BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
 950     BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
 951     BoolVariable('USE_PNG',  'Enable support for PNG images', have_png),
 952     BoolVariable('CP_ANNOTATE', 'Enable critical path annotation capability',
 953                  False),
 954     BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models',
 955                  have_kvm),
 956     BoolVariable('USE_TUNTAP',
 957                  'Enable using a tap device to bridge to the host network',
 958                  have_tuntap),
 959     BoolVariable('BUILD_GPU', 'Build the compute-GPU model', False),
 960     EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
 961                   all_protocols),
 962     EnumVariable('BACKTRACE_IMPL', 'Post-mortem dump implementation',
 963                  backtrace_impls[-1], backtrace_impls)
 964     )
 965
 966 # These variables get exported to #defines in config/*.hh (see src/SConscript).
 967 export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'TARGET_GPU_ISA',
 968                 'CP_ANNOTATE', 'USE_POSIX_CLOCK', 'USE_KVM', 'USE_TUNTAP',
 969                 'PROTOCOL', 'HAVE_PROTOBUF', 'HAVE_PERF_ATTR_EXCLUDE_HOST',
 970                 'USE_PNG']
 971
 972 ###################################################
 973 #
 974 # Define a SCons builder for configuration flag headers.
 975 #
 976 ###################################################
 977
 978 # This function generates a config header file that #defines the
 979 # variable symbol to the current variable setting (0 or 1).  The source
 980 # operands are the name of the variable and a Value node containing the
 981 # value of the variable.
 982 def build_config_file(target, source, env):
 983     (variable, value) = [s.get_contents() for s in source]
 984     f = file(str(target[0]), 'w')
 985     print >> f, '#define', variable, value
 986     f.close()
 987     return None
 988
 989 # Combine the two functions into a scons Action object.
 990 config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
 991
 992 # The emitter munges the source & target node lists to reflect what
 993 # we're really doing.
 994 def config_emitter(target, source, env):
 995     # extract variable name from Builder arg
 996     variable = str(target[0])
 997     # True target is config header file
 998     target = joinpath('config', variable.lower() + '.hh')
 999     val = env[variable]
1000     if isinstance(val, bool):
1001         # Force value to 0/1
1002         val = int(val)
1003     elif isinstance(val, str):
1004         val = '"' + val + '"'
1005
1006     # Sources are variable name & value (packaged in SCons Value nodes)
1007     return ([target], [Value(variable), Value(val)])
1008
1009 config_builder = Builder(emitter = config_emitter, action = config_action)
1010
1011 main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1012
1013 ###################################################
1014 #
1015 # Builders for static and shared partially linked object files.
1016 #
1017 ###################################################
1018
1019 partial_static_builder = Builder(action=SCons.Defaults.LinkAction,
1020                                  src_suffix='$OBJSUFFIX',
1021                                  src_builder=['StaticObject', 'Object'],
1022                                  LINKFLAGS='$PLINKFLAGS',
1023                                  LIBS='')
1024
1025 def partial_shared_emitter(target, source, env):
1026     for tgt in target:
1027         tgt.attributes.shared = 1
1028     return (target, source)
1029 partial_shared_builder = Builder(action=SCons.Defaults.ShLinkAction,
1030                                  emitter=partial_shared_emitter,
1031                                  src_suffix='$SHOBJSUFFIX',
1032                                  src_builder='SharedObject',
1033                                  SHLINKFLAGS='$PSHLINKFLAGS',
1034                                  LIBS='')
1035
1036 main.Append(BUILDERS = { 'PartialShared' : partial_shared_builder,
1037                          'PartialStatic' : partial_static_builder })
1038
1039 # builds in ext are shared across all configs in the build root.
1040 ext_dir = abspath(joinpath(str(main.root), 'ext'))
1041 ext_build_dirs = []
1042 for root, dirs, files in os.walk(ext_dir):
1043     if 'SConscript' in files:
1044         build_dir = os.path.relpath(root, ext_dir)
1045         ext_build_dirs.append(build_dir)
1046         main.SConscript(joinpath(root, 'SConscript'),
1047                         variant_dir=joinpath(build_root, build_dir))
1048
1049 main.Prepend(CPPPATH=Dir('ext/pybind11/include/'))
1050
1051 ###################################################
1052 #
1053 # This builder and wrapper method are used to set up a directory with
1054 # switching headers. Those are headers which are in a generic location and
1055 # that include more specific headers from a directory chosen at build time
1056 # based on the current build settings.
1057 #
1058 ###################################################
1059
1060 def build_switching_header(target, source, env):
1061     path = str(target[0])
1062     subdir = str(source[0])
1063     dp, fp = os.path.split(path)
1064     dp = os.path.relpath(os.path.realpath(dp),
1065                          os.path.realpath(env['BUILDDIR']))
1066     with open(path, 'w') as hdr:
1067         print >>hdr, '#include "%s/%s/%s"' % (dp, subdir, fp)
1068
1069 switching_header_action = MakeAction(build_switching_header,
1070                                      Transform('GENERATE'))
1071
1072 switching_header_builder = Builder(action=switching_header_action,
1073                                    source_factory=Value,
1074                                    single_source=True)
1075
1076 main.Append(BUILDERS = { 'SwitchingHeader': switching_header_builder })
1077
1078 def switching_headers(self, headers, source):
1079     for header in headers:
1080         self.SwitchingHeader(header, source)
1081
1082 main.AddMethod(switching_headers, 'SwitchingHeaders')
1083
1084 ###################################################
1085 #
1086 # Define build environments for selected configurations.
1087 #
1088 ###################################################
1089
1090 for variant_path in variant_paths:
1091     if not GetOption('silent'):
1092         print "Building in", variant_path
1093
1094     # Make a copy of the build-root environment to use for this config.
1095     env = main.Clone()
1096     env['BUILDDIR'] = variant_path
1097
1098     # variant_dir is the tail component of build path, and is used to
1099     # determine the build parameters (e.g., 'ALPHA_SE')
1100     (build_root, variant_dir) = splitpath(variant_path)
1101
1102     # Set env variables according to the build directory config.
1103     sticky_vars.files = []
1104     # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1105     # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1106     # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1107     current_vars_file = joinpath(build_root, 'variables', variant_dir)
1108     if isfile(current_vars_file):
1109         sticky_vars.files.append(current_vars_file)
1110         if not GetOption('silent'):
1111             print "Using saved variables file %s" % current_vars_file
1112     elif variant_dir in ext_build_dirs:
1113         # Things in ext are built without a variant directory.
1114         continue
1115     else:
1116         # Build dir-specific variables file doesn't exist.
1117
1118         # Make sure the directory is there so we can create it later
1119         opt_dir = dirname(current_vars_file)
1120         if not isdir(opt_dir):
1121             mkdir(opt_dir)
1122
1123         # Get default build variables from source tree.  Variables are
1124         # normally determined by name of $VARIANT_DIR, but can be
1125         # overridden by '--default=' arg on command line.
1126         default = GetOption('default')
1127         opts_dir = joinpath(main.root.abspath, 'build_opts')
1128         if default:
1129             default_vars_files = [joinpath(build_root, 'variables', default),
1130                                   joinpath(opts_dir, default)]
1131         else:
1132             default_vars_files = [joinpath(opts_dir, variant_dir)]
1133         existing_files = filter(isfile, default_vars_files)
1134         if existing_files:
1135             default_vars_file = existing_files[0]
1136             sticky_vars.files.append(default_vars_file)
1137             print "Variables file %s not found,\n  using defaults in %s" \
1138                   % (current_vars_file, default_vars_file)
1139         else:
1140             print "Error: cannot find variables file %s or " \
1141                   "default file(s) %s" \
1142                   % (current_vars_file, ' or '.join(default_vars_files))
1143             Exit(1)
1144
1145     # Apply current variable settings to env
1146     sticky_vars.Update(env)
1147
1148     help_texts["local_vars"] += \
1149         "Build variables for %s:\n" % variant_dir \
1150                  + sticky_vars.GenerateHelpText(env)
1151
1152     # Process variable settings.
1153
1154     if not have_fenv and env['USE_FENV']:
1155         print "Warning: <fenv.h> not available; " \
1156               "forcing USE_FENV to False in", variant_dir + "."
1157         env['USE_FENV'] = False
1158
1159     if not env['USE_FENV']:
1160         print "Warning: No IEEE FP rounding mode control in", variant_dir + "."
1161         print "         FP results may deviate slightly from other platforms."
1162
1163     if not have_png and env['USE_PNG']:
1164         print "Warning: <png.h> not available; " \
1165               "forcing USE_PNG to False in", variant_dir + "."
1166         env['USE_PNG'] = False
1167
1168     if env['USE_PNG']:
1169         env.Append(LIBS=['png'])
1170
1171     if env['EFENCE']:
1172         env.Append(LIBS=['efence'])
1173
1174     if env['USE_KVM']:
1175         if not have_kvm:
1176             print "Warning: Can not enable KVM, host seems to lack KVM support"
1177             env['USE_KVM'] = False
1178         elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1179             print "Info: KVM support disabled due to unsupported host and " \
1180                 "target ISA combination"
1181             env['USE_KVM'] = False
1182
1183     if env['USE_TUNTAP']:
1184         if not have_tuntap:
1185             print "Warning: Can't connect EtherTap with a tap device."
1186             env['USE_TUNTAP'] = False
1187
1188     if env['BUILD_GPU']:
1189         env.Append(CPPDEFINES=['BUILD_GPU'])
1190
1191     # Warn about missing optional functionality
1192     if env['USE_KVM']:
1193         if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1194             print "Warning: perf_event headers lack support for the " \
1195                 "exclude_host attribute. KVM instruction counts will " \
1196                 "be inaccurate."
1197
1198     # Save sticky variable settings back to current variables file
1199     sticky_vars.Save(current_vars_file, env)
1200
1201     if env['USE_SSE2']:
1202         env.Append(CCFLAGS=['-msse2'])
1203
1204     # The src/SConscript file sets up the build rules in 'env' according
1205     # to the configured variables.  It returns a list of environments,
1206     # one for each variant build (debug, opt, etc.)
1207     SConscript('src/SConscript', variant_dir = variant_path, exports = 'env')
1208
1209 # base help text
1210 Help('''
1211 Usage: scons [scons options] [build variables] [target(s)]
1212
1213 Extra scons options:
1214 %(options)s
1215
1216 Global build variables:
1217 %(global_vars)s
1218
1219 %(local_vars)s
1220 ''' % help_texts)