SConstruct revision 9846:a4b5fd8937c9
1# -*- mode:python -*-
2
3# Copyright (c) 2013 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# Check for recent-enough Python and SCons versions.
82try:
83    # Really old versions of scons only take two options for the
84    # function, so check once without the revision and once with the
85    # revision, the first instance will fail for stuff other than
86    # 0.98, and the second will fail for 0.98.0
87    EnsureSConsVersion(0, 98)
88    EnsureSConsVersion(0, 98, 1)
89except SystemExit, e:
90    print """
91For more details, see:
92    http://gem5.org/Dependencies
93"""
94    raise
95
96# We ensure the python version early because because python-config
97# requires python 2.5
98try:
99    EnsurePythonVersion(2, 5)
100except SystemExit, e:
101    print """
102You can use a non-default installation of the Python interpreter by
103rearranging your PATH so that scons finds the non-default 'python' and
104'python-config' first.
105
106For more details, see:
107    http://gem5.org/wiki/index.php/Using_a_non-default_Python_installation
108"""
109    raise
110
111# Global Python includes
112import os
113import re
114import subprocess
115import sys
116
117from os import mkdir, environ
118from os.path import abspath, basename, dirname, expanduser, normpath
119from os.path import exists,  isdir, isfile
120from os.path import join as joinpath, split as splitpath
121
122# SCons includes
123import SCons
124import SCons.Node
125
126extra_python_paths = [
127    Dir('src/python').srcnode().abspath, # gem5 includes
128    Dir('ext/ply').srcnode().abspath, # ply is used by several files
129    ]
130
131sys.path[1:1] = extra_python_paths
132
133from m5.util import compareVersions, readCommand
134from m5.util.terminal import get_termcap
135
136help_texts = {
137    "options" : "",
138    "global_vars" : "",
139    "local_vars" : ""
140}
141
142Export("help_texts")
143
144
145# There's a bug in scons in that (1) by default, the help texts from
146# AddOption() are supposed to be displayed when you type 'scons -h'
147# and (2) you can override the help displayed by 'scons -h' using the
148# Help() function, but these two features are incompatible: once
149# you've overridden the help text using Help(), there's no way to get
150# at the help texts from AddOptions.  See:
151#     http://scons.tigris.org/issues/show_bug.cgi?id=2356
152#     http://scons.tigris.org/issues/show_bug.cgi?id=2611
153# This hack lets us extract the help text from AddOptions and
154# re-inject it via Help().  Ideally someday this bug will be fixed and
155# we can just use AddOption directly.
156def AddLocalOption(*args, **kwargs):
157    col_width = 30
158
159    help = "  " + ", ".join(args)
160    if "help" in kwargs:
161        length = len(help)
162        if length >= col_width:
163            help += "\n" + " " * col_width
164        else:
165            help += " " * (col_width - length)
166        help += kwargs["help"]
167    help_texts["options"] += help + "\n"
168
169    AddOption(*args, **kwargs)
170
171AddLocalOption('--colors', dest='use_colors', action='store_true',
172               help="Add color to abbreviated scons output")
173AddLocalOption('--no-colors', dest='use_colors', action='store_false',
174               help="Don't add color to abbreviated scons output")
175AddLocalOption('--default', dest='default', type='string', action='store',
176               help='Override which build_opts file to use for defaults')
177AddLocalOption('--ignore-style', dest='ignore_style', action='store_true',
178               help='Disable style checking hooks')
179AddLocalOption('--no-lto', dest='no_lto', action='store_true',
180               help='Disable Link-Time Optimization for fast')
181AddLocalOption('--update-ref', dest='update_ref', action='store_true',
182               help='Update test reference outputs')
183AddLocalOption('--verbose', dest='verbose', action='store_true',
184               help='Print full tool command lines')
185
186termcap = get_termcap(GetOption('use_colors'))
187
188########################################################################
189#
190# Set up the main build environment.
191#
192########################################################################
193use_vars = set([ 'AS', 'AR', 'CC', 'CXX', 'HOME', 'LD_LIBRARY_PATH',
194                 'LIBRARY_PATH', 'PATH', 'PKG_CONFIG_PATH', 'PYTHONPATH',
195                 'RANLIB', 'SWIG' ])
196
197use_prefixes = [
198    "M5",           # M5 configuration (e.g., path to kernels)
199    "DISTCC_",      # distcc (distributed compiler wrapper) configuration
200    "CCACHE_",      # ccache (caching compiler wrapper) configuration
201    "CCC_",         # clang static analyzer configuration
202    ]
203
204use_env = {}
205for key,val in os.environ.iteritems():
206    if key in use_vars or \
207            any([key.startswith(prefix) for prefix in use_prefixes]):
208        use_env[key] = val
209
210main = Environment(ENV=use_env)
211main.Decider('MD5-timestamp')
212main.root = Dir(".")         # The current directory (where this file lives).
213main.srcdir = Dir("src")     # The source directory
214
215main_dict_keys = main.Dictionary().keys()
216
217# Check that we have a C/C++ compiler
218if not ('CC' in main_dict_keys and 'CXX' in main_dict_keys):
219    print "No C++ compiler installed (package g++ on Ubuntu and RedHat)"
220    Exit(1)
221
222# Check that swig is present
223if not 'SWIG' in main_dict_keys:
224    print "swig is not installed (package swig on Ubuntu and RedHat)"
225    Exit(1)
226
227# add useful python code PYTHONPATH so it can be used by subprocesses
228# as well
229main.AppendENVPath('PYTHONPATH', extra_python_paths)
230
231########################################################################
232#
233# Mercurial Stuff.
234#
235# If the gem5 directory is a mercurial repository, we should do some
236# extra things.
237#
238########################################################################
239
240hgdir = main.root.Dir(".hg")
241
242mercurial_style_message = """
243You're missing the gem5 style hook, which automatically checks your code
244against the gem5 style rules on hg commit and qrefresh commands.  This
245script will now install the hook in your .hg/hgrc file.
246Press enter to continue, or ctrl-c to abort: """
247
248mercurial_style_hook = """
249# The following lines were automatically added by gem5/SConstruct
250# to provide the gem5 style-checking hooks
251[extensions]
252style = %s/util/style.py
253
254[hooks]
255pretxncommit.style = python:style.check_style
256pre-qrefresh.style = python:style.check_style
257# End of SConstruct additions
258
259""" % (main.root.abspath)
260
261mercurial_lib_not_found = """
262Mercurial libraries cannot be found, ignoring style hook.  If
263you are a gem5 developer, please fix this and run the style
264hook. It is important.
265"""
266
267# Check for style hook and prompt for installation if it's not there.
268# Skip this if --ignore-style was specified, there's no .hg dir to
269# install a hook in, or there's no interactive terminal to prompt.
270if not GetOption('ignore_style') and hgdir.exists() and sys.stdin.isatty():
271    style_hook = True
272    try:
273        from mercurial import ui
274        ui = ui.ui()
275        ui.readconfig(hgdir.File('hgrc').abspath)
276        style_hook = ui.config('hooks', 'pretxncommit.style', None) and \
277                     ui.config('hooks', 'pre-qrefresh.style', None)
278    except ImportError:
279        print mercurial_lib_not_found
280
281    if not style_hook:
282        print mercurial_style_message,
283        # continue unless user does ctrl-c/ctrl-d etc.
284        try:
285            raw_input()
286        except:
287            print "Input exception, exiting scons.\n"
288            sys.exit(1)
289        hgrc_path = '%s/.hg/hgrc' % main.root.abspath
290        print "Adding style hook to", hgrc_path, "\n"
291        try:
292            hgrc = open(hgrc_path, 'a')
293            hgrc.write(mercurial_style_hook)
294            hgrc.close()
295        except:
296            print "Error updating", hgrc_path
297            sys.exit(1)
298
299
300###################################################
301#
302# Figure out which configurations to set up based on the path(s) of
303# the target(s).
304#
305###################################################
306
307# Find default configuration & binary.
308Default(environ.get('M5_DEFAULT_BINARY', 'build/ALPHA/gem5.debug'))
309
310# helper function: find last occurrence of element in list
311def rfind(l, elt, offs = -1):
312    for i in range(len(l)+offs, 0, -1):
313        if l[i] == elt:
314            return i
315    raise ValueError, "element not found"
316
317# Take a list of paths (or SCons Nodes) and return a list with all
318# paths made absolute and ~-expanded.  Paths will be interpreted
319# relative to the launch directory unless a different root is provided
320def makePathListAbsolute(path_list, root=GetLaunchDir()):
321    return [abspath(joinpath(root, expanduser(str(p))))
322            for p in path_list]
323
324# Each target must have 'build' in the interior of the path; the
325# directory below this will determine the build parameters.  For
326# example, for target 'foo/bar/build/ALPHA_SE/arch/alpha/blah.do' we
327# recognize that ALPHA_SE specifies the configuration because it
328# follow 'build' in the build path.
329
330# The funky assignment to "[:]" is needed to replace the list contents
331# in place rather than reassign the symbol to a new list, which
332# doesn't work (obviously!).
333BUILD_TARGETS[:] = makePathListAbsolute(BUILD_TARGETS)
334
335# Generate a list of the unique build roots and configs that the
336# collected targets reference.
337variant_paths = []
338build_root = None
339for t in BUILD_TARGETS:
340    path_dirs = t.split('/')
341    try:
342        build_top = rfind(path_dirs, 'build', -2)
343    except:
344        print "Error: no non-leaf 'build' dir found on target path", t
345        Exit(1)
346    this_build_root = joinpath('/',*path_dirs[:build_top+1])
347    if not build_root:
348        build_root = this_build_root
349    else:
350        if this_build_root != build_root:
351            print "Error: build targets not under same build root\n"\
352                  "  %s\n  %s" % (build_root, this_build_root)
353            Exit(1)
354    variant_path = joinpath('/',*path_dirs[:build_top+2])
355    if variant_path not in variant_paths:
356        variant_paths.append(variant_path)
357
358# Make sure build_root exists (might not if this is the first build there)
359if not isdir(build_root):
360    mkdir(build_root)
361main['BUILDROOT'] = build_root
362
363Export('main')
364
365main.SConsignFile(joinpath(build_root, "sconsign"))
366
367# Default duplicate option is to use hard links, but this messes up
368# when you use emacs to edit a file in the target dir, as emacs moves
369# file to file~ then copies to file, breaking the link.  Symbolic
370# (soft) links work better.
371main.SetOption('duplicate', 'soft-copy')
372
373#
374# Set up global sticky variables... these are common to an entire build
375# tree (not specific to a particular build like ALPHA_SE)
376#
377
378global_vars_file = joinpath(build_root, 'variables.global')
379
380global_vars = Variables(global_vars_file, args=ARGUMENTS)
381
382global_vars.AddVariables(
383    ('CC', 'C compiler', environ.get('CC', main['CC'])),
384    ('CXX', 'C++ compiler', environ.get('CXX', main['CXX'])),
385    ('SWIG', 'SWIG tool', environ.get('SWIG', main['SWIG'])),
386    ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
387    ('BATCH', 'Use batch pool for build and tests', False),
388    ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
389    ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
390    ('EXTRAS', 'Add extra directories to the compilation', '')
391    )
392
393# Update main environment with values from ARGUMENTS & global_vars_file
394global_vars.Update(main)
395help_texts["global_vars"] += global_vars.GenerateHelpText(main)
396
397# Save sticky variable settings back to current variables file
398global_vars.Save(global_vars_file, main)
399
400# Parse EXTRAS variable to build list of all directories where we're
401# look for sources etc.  This list is exported as extras_dir_list.
402base_dir = main.srcdir.abspath
403if main['EXTRAS']:
404    extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
405else:
406    extras_dir_list = []
407
408Export('base_dir')
409Export('extras_dir_list')
410
411# the ext directory should be on the #includes path
412main.Append(CPPPATH=[Dir('ext')])
413
414def strip_build_path(path, env):
415    path = str(path)
416    variant_base = env['BUILDROOT'] + os.path.sep
417    if path.startswith(variant_base):
418        path = path[len(variant_base):]
419    elif path.startswith('build/'):
420        path = path[6:]
421    return path
422
423# Generate a string of the form:
424#   common/path/prefix/src1, src2 -> tgt1, tgt2
425# to print while building.
426class Transform(object):
427    # all specific color settings should be here and nowhere else
428    tool_color = termcap.Normal
429    pfx_color = termcap.Yellow
430    srcs_color = termcap.Yellow + termcap.Bold
431    arrow_color = termcap.Blue + termcap.Bold
432    tgts_color = termcap.Yellow + termcap.Bold
433
434    def __init__(self, tool, max_sources=99):
435        self.format = self.tool_color + (" [%8s] " % tool) \
436                      + self.pfx_color + "%s" \
437                      + self.srcs_color + "%s" \
438                      + self.arrow_color + " -> " \
439                      + self.tgts_color + "%s" \
440                      + termcap.Normal
441        self.max_sources = max_sources
442
443    def __call__(self, target, source, env, for_signature=None):
444        # truncate source list according to max_sources param
445        source = source[0:self.max_sources]
446        def strip(f):
447            return strip_build_path(str(f), env)
448        if len(source) > 0:
449            srcs = map(strip, source)
450        else:
451            srcs = ['']
452        tgts = map(strip, target)
453        # surprisingly, os.path.commonprefix is a dumb char-by-char string
454        # operation that has nothing to do with paths.
455        com_pfx = os.path.commonprefix(srcs + tgts)
456        com_pfx_len = len(com_pfx)
457        if com_pfx:
458            # do some cleanup and sanity checking on common prefix
459            if com_pfx[-1] == ".":
460                # prefix matches all but file extension: ok
461                # back up one to change 'foo.cc -> o' to 'foo.cc -> .o'
462                com_pfx = com_pfx[0:-1]
463            elif com_pfx[-1] == "/":
464                # common prefix is directory path: OK
465                pass
466            else:
467                src0_len = len(srcs[0])
468                tgt0_len = len(tgts[0])
469                if src0_len == com_pfx_len:
470                    # source is a substring of target, OK
471                    pass
472                elif tgt0_len == com_pfx_len:
473                    # target is a substring of source, need to back up to
474                    # avoid empty string on RHS of arrow
475                    sep_idx = com_pfx.rfind(".")
476                    if sep_idx != -1:
477                        com_pfx = com_pfx[0:sep_idx]
478                    else:
479                        com_pfx = ''
480                elif src0_len > com_pfx_len and srcs[0][com_pfx_len] == ".":
481                    # still splitting at file extension: ok
482                    pass
483                else:
484                    # probably a fluke; ignore it
485                    com_pfx = ''
486        # recalculate length in case com_pfx was modified
487        com_pfx_len = len(com_pfx)
488        def fmt(files):
489            f = map(lambda s: s[com_pfx_len:], files)
490            return ', '.join(f)
491        return self.format % (com_pfx, fmt(srcs), fmt(tgts))
492
493Export('Transform')
494
495# enable the regression script to use the termcap
496main['TERMCAP'] = termcap
497
498if GetOption('verbose'):
499    def MakeAction(action, string, *args, **kwargs):
500        return Action(action, *args, **kwargs)
501else:
502    MakeAction = Action
503    main['CCCOMSTR']        = Transform("CC")
504    main['CXXCOMSTR']       = Transform("CXX")
505    main['ASCOMSTR']        = Transform("AS")
506    main['SWIGCOMSTR']      = Transform("SWIG")
507    main['ARCOMSTR']        = Transform("AR", 0)
508    main['LINKCOMSTR']      = Transform("LINK", 0)
509    main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
510    main['M4COMSTR']        = Transform("M4")
511    main['SHCCCOMSTR']      = Transform("SHCC")
512    main['SHCXXCOMSTR']     = Transform("SHCXX")
513Export('MakeAction')
514
515# Initialize the Link-Time Optimization (LTO) flags
516main['LTO_CCFLAGS'] = []
517main['LTO_LDFLAGS'] = []
518
519# According to the readme, tcmalloc works best if the compiler doesn't
520# assume that we're using the builtin malloc and friends. These flags
521# are compiler-specific, so we need to set them after we detect which
522# compiler we're using.
523main['TCMALLOC_CCFLAGS'] = []
524
525CXX_version = readCommand([main['CXX'],'--version'], exception=False)
526CXX_V = readCommand([main['CXX'],'-V'], exception=False)
527
528main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
529main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
530if main['GCC'] + main['CLANG'] > 1:
531    print 'Error: How can we have two at the same time?'
532    Exit(1)
533
534# Set up default C++ compiler flags
535if main['GCC'] or main['CLANG']:
536    # As gcc and clang share many flags, do the common parts here
537    main.Append(CCFLAGS=['-pipe'])
538    main.Append(CCFLAGS=['-fno-strict-aliasing'])
539    # Enable -Wall and then disable the few warnings that we
540    # consistently violate
541    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
542    # We always compile using C++11, but only gcc >= 4.7 and clang 3.1
543    # actually use that name, so we stick with c++0x
544    main.Append(CXXFLAGS=['-std=c++0x'])
545    # Add selected sanity checks from -Wextra
546    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
547                          '-Woverloaded-virtual'])
548else:
549    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
550    print "Don't know what compiler options to use for your compiler."
551    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
552    print termcap.Yellow + '       version:' + termcap.Normal,
553    if not CXX_version:
554        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
555               termcap.Normal
556    else:
557        print CXX_version.replace('\n', '<nl>')
558    print "       If you're trying to use a compiler other than GCC"
559    print "       or clang, there appears to be something wrong with your"
560    print "       environment."
561    print "       "
562    print "       If you are trying to use a compiler other than those listed"
563    print "       above you will need to ease fix SConstruct and "
564    print "       src/SConscript to support that compiler."
565    Exit(1)
566
567if main['GCC']:
568    # Check for a supported version of gcc, >= 4.4 is needed for c++0x
569    # support. See http://gcc.gnu.org/projects/cxx0x.html for details
570    gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
571    if compareVersions(gcc_version, "4.4") < 0:
572        print 'Error: gcc version 4.4 or newer required.'
573        print '       Installed version:', gcc_version
574        Exit(1)
575
576    main['GCC_VERSION'] = gcc_version
577
578    # Check for versions with bugs
579    if not compareVersions(gcc_version, '4.4.1') or \
580       not compareVersions(gcc_version, '4.4.2'):
581        print 'Info: Tree vectorizer in GCC 4.4.1 & 4.4.2 is buggy, disabling.'
582        main.Append(CCFLAGS=['-fno-tree-vectorize'])
583
584    # LTO support is only really working properly from 4.6 and beyond
585    if compareVersions(gcc_version, '4.6') >= 0:
586        # Add the appropriate Link-Time Optimization (LTO) flags
587        # unless LTO is explicitly turned off. Note that these flags
588        # are only used by the fast target.
589        if not GetOption('no_lto'):
590            # Pass the LTO flag when compiling to produce GIMPLE
591            # output, we merely create the flags here and only append
592            # them later/
593            main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
594
595            # Use the same amount of jobs for LTO as we are running
596            # scons with, we hardcode the use of the linker plugin
597            # which requires either gold or GNU ld >= 2.21
598            main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs'),
599                                   '-fuse-linker-plugin']
600
601    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
602                                  '-fno-builtin-realloc', '-fno-builtin-free'])
603
604elif main['CLANG']:
605    # Check for a supported version of clang, >= 2.9 is needed to
606    # support similar features as gcc 4.4. See
607    # http://clang.llvm.org/cxx_status.html for details
608    clang_version_re = re.compile(".* version (\d+\.\d+)")
609    clang_version_match = clang_version_re.match(CXX_version)
610    if (clang_version_match):
611        clang_version = clang_version_match.groups()[0]
612        if compareVersions(clang_version, "2.9") < 0:
613            print 'Error: clang version 2.9 or newer required.'
614            print '       Installed version:', clang_version
615            Exit(1)
616    else:
617        print 'Error: Unable to determine clang version.'
618        Exit(1)
619
620    # clang has a few additional warnings that we disable,
621    # tautological comparisons are allowed due to unsigned integers
622    # being compared to constants that happen to be 0, and extraneous
623    # parantheses are allowed due to Ruby's printing of the AST,
624    # finally self assignments are allowed as the generated CPU code
625    # is relying on this
626    main.Append(CCFLAGS=['-Wno-tautological-compare',
627                         '-Wno-parentheses',
628                         '-Wno-self-assign'])
629
630    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
631
632    # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
633    # opposed to libstdc++, as the later is dated.
634    if sys.platform == "darwin":
635        main.Append(CXXFLAGS=['-stdlib=libc++'])
636        main.Append(LIBS=['c++'])
637
638else:
639    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
640    print "Don't know what compiler options to use for your compiler."
641    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
642    print termcap.Yellow + '       version:' + termcap.Normal,
643    if not CXX_version:
644        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
645               termcap.Normal
646    else:
647        print CXX_version.replace('\n', '<nl>')
648    print "       If you're trying to use a compiler other than GCC"
649    print "       or clang, there appears to be something wrong with your"
650    print "       environment."
651    print "       "
652    print "       If you are trying to use a compiler other than those listed"
653    print "       above you will need to ease fix SConstruct and "
654    print "       src/SConscript to support that compiler."
655    Exit(1)
656
657# Set up common yacc/bison flags (needed for Ruby)
658main['YACCFLAGS'] = '-d'
659main['YACCHXXFILESUFFIX'] = '.hh'
660
661# Do this after we save setting back, or else we'll tack on an
662# extra 'qdo' every time we run scons.
663if main['BATCH']:
664    main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
665    main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
666    main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
667    main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
668    main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
669
670if sys.platform == 'cygwin':
671    # cygwin has some header file issues...
672    main.Append(CCFLAGS=["-Wno-uninitialized"])
673
674# Check for the protobuf compiler
675protoc_version = readCommand([main['PROTOC'], '--version'],
676                             exception='').split()
677
678# First two words should be "libprotoc x.y.z"
679if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
680    print termcap.Yellow + termcap.Bold + \
681        'Warning: Protocol buffer compiler (protoc) not found.\n' + \
682        '         Please install protobuf-compiler for tracing support.' + \
683        termcap.Normal
684    main['PROTOC'] = False
685else:
686    # Based on the availability of the compress stream wrappers,
687    # require 2.1.0
688    min_protoc_version = '2.1.0'
689    if compareVersions(protoc_version[1], min_protoc_version) < 0:
690        print termcap.Yellow + termcap.Bold + \
691            'Warning: protoc version', min_protoc_version, \
692            'or newer required.\n' + \
693            '         Installed version:', protoc_version[1], \
694            termcap.Normal
695        main['PROTOC'] = False
696    else:
697        # Attempt to determine the appropriate include path and
698        # library path using pkg-config, that means we also need to
699        # check for pkg-config. Note that it is possible to use
700        # protobuf without the involvement of pkg-config. Later on we
701        # check go a library config check and at that point the test
702        # will fail if libprotobuf cannot be found.
703        if readCommand(['pkg-config', '--version'], exception=''):
704            try:
705                # Attempt to establish what linking flags to add for protobuf
706                # using pkg-config
707                main.ParseConfig('pkg-config --cflags --libs-only-L protobuf')
708            except:
709                print termcap.Yellow + termcap.Bold + \
710                    'Warning: pkg-config could not get protobuf flags.' + \
711                    termcap.Normal
712
713# Check for SWIG
714if not main.has_key('SWIG'):
715    print 'Error: SWIG utility not found.'
716    print '       Please install (see http://www.swig.org) and retry.'
717    Exit(1)
718
719# Check for appropriate SWIG version
720swig_version = readCommand([main['SWIG'], '-version'], exception='').split()
721# First 3 words should be "SWIG Version x.y.z"
722if len(swig_version) < 3 or \
723        swig_version[0] != 'SWIG' or swig_version[1] != 'Version':
724    print 'Error determining SWIG version.'
725    Exit(1)
726
727min_swig_version = '1.3.34'
728if compareVersions(swig_version[2], min_swig_version) < 0:
729    print 'Error: SWIG version', min_swig_version, 'or newer required.'
730    print '       Installed version:', swig_version[2]
731    Exit(1)
732
733if swig_version[2] in ["2.0.9", "2.0.10"]:
734    print '\n' + termcap.Yellow + termcap.Bold + \
735        'Warning: SWIG version 2.0.9/10 sometimes generates broken code.\n' + \
736        termcap.Normal + \
737        'This problem only affects some platforms and some Python\n' + \
738        'versions. See the following SWIG bug report for details:\n' + \
739        'http://sourceforge.net/p/swig/bugs/1297/\n'
740
741
742# Set up SWIG flags & scanner
743swig_flags=Split('-c++ -python -modern -templatereduce $_CPPINCFLAGS')
744main.Append(SWIGFLAGS=swig_flags)
745
746# filter out all existing swig scanners, they mess up the dependency
747# stuff for some reason
748scanners = []
749for scanner in main['SCANNERS']:
750    skeys = scanner.skeys
751    if skeys == '.i':
752        continue
753
754    if isinstance(skeys, (list, tuple)) and '.i' in skeys:
755        continue
756
757    scanners.append(scanner)
758
759# add the new swig scanner that we like better
760from SCons.Scanner import ClassicCPP as CPPScanner
761swig_inc_re = '^[ \t]*[%,#][ \t]*(?:include|import)[ \t]*(<|")([^>"]+)(>|")'
762scanners.append(CPPScanner("SwigScan", [ ".i" ], "CPPPATH", swig_inc_re))
763
764# replace the scanners list that has what we want
765main['SCANNERS'] = scanners
766
767# Add a custom Check function to the Configure context so that we can
768# figure out if the compiler adds leading underscores to global
769# variables.  This is needed for the autogenerated asm files that we
770# use for embedding the python code.
771def CheckLeading(context):
772    context.Message("Checking for leading underscore in global variables...")
773    # 1) Define a global variable called x from asm so the C compiler
774    #    won't change the symbol at all.
775    # 2) Declare that variable.
776    # 3) Use the variable
777    #
778    # If the compiler prepends an underscore, this will successfully
779    # link because the external symbol 'x' will be called '_x' which
780    # was defined by the asm statement.  If the compiler does not
781    # prepend an underscore, this will not successfully link because
782    # '_x' will have been defined by assembly, while the C portion of
783    # the code will be trying to use 'x'
784    ret = context.TryLink('''
785        asm(".globl _x; _x: .byte 0");
786        extern int x;
787        int main() { return x; }
788        ''', extension=".c")
789    context.env.Append(LEADING_UNDERSCORE=ret)
790    context.Result(ret)
791    return ret
792
793# Platform-specific configuration.  Note again that we assume that all
794# builds under a given build root run on the same host platform.
795conf = Configure(main,
796                 conf_dir = joinpath(build_root, '.scons_config'),
797                 log_file = joinpath(build_root, 'scons_config.log'),
798                 custom_tests = { 'CheckLeading' : CheckLeading })
799
800# Check for leading underscores.  Don't really need to worry either
801# way so don't need to check the return code.
802conf.CheckLeading()
803
804# Check if we should compile a 64 bit binary on Mac OS X/Darwin
805try:
806    import platform
807    uname = platform.uname()
808    if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
809        if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
810            main.Append(CCFLAGS=['-arch', 'x86_64'])
811            main.Append(CFLAGS=['-arch', 'x86_64'])
812            main.Append(LINKFLAGS=['-arch', 'x86_64'])
813            main.Append(ASFLAGS=['-arch', 'x86_64'])
814except:
815    pass
816
817# Recent versions of scons substitute a "Null" object for Configure()
818# when configuration isn't necessary, e.g., if the "--help" option is
819# present.  Unfortuantely this Null object always returns false,
820# breaking all our configuration checks.  We replace it with our own
821# more optimistic null object that returns True instead.
822if not conf:
823    def NullCheck(*args, **kwargs):
824        return True
825
826    class NullConf:
827        def __init__(self, env):
828            self.env = env
829        def Finish(self):
830            return self.env
831        def __getattr__(self, mname):
832            return NullCheck
833
834    conf = NullConf(main)
835
836# Cache build files in the supplied directory.
837if main['M5_BUILD_CACHE']:
838    print 'Using build cache located at', main['M5_BUILD_CACHE']
839    CacheDir(main['M5_BUILD_CACHE'])
840
841# Find Python include and library directories for embedding the
842# interpreter. We rely on python-config to resolve the appropriate
843# includes and linker flags. ParseConfig does not seem to understand
844# the more exotic linker flags such as -Xlinker and -export-dynamic so
845# we add them explicitly below. If you want to link in an alternate
846# version of python, see above for instructions on how to invoke
847# scons with the appropriate PATH set.
848py_includes = readCommand(['python-config', '--includes'],
849                          exception='').split()
850# Strip the -I from the include folders before adding them to the
851# CPPPATH
852main.Append(CPPPATH=map(lambda inc: inc[2:], py_includes))
853
854# Read the linker flags and split them into libraries and other link
855# flags. The libraries are added later through the call the CheckLib.
856py_ld_flags = readCommand(['python-config', '--ldflags'], exception='').split()
857py_libs = []
858for lib in py_ld_flags:
859     if not lib.startswith('-l'):
860         main.Append(LINKFLAGS=[lib])
861     else:
862         lib = lib[2:]
863         if lib not in py_libs:
864             py_libs.append(lib)
865
866# verify that this stuff works
867if not conf.CheckHeader('Python.h', '<>'):
868    print "Error: can't find Python.h header in", py_includes
869    print "Install Python headers (package python-dev on Ubuntu and RedHat)"
870    Exit(1)
871
872for lib in py_libs:
873    if not conf.CheckLib(lib):
874        print "Error: can't find library %s required by python" % lib
875        Exit(1)
876
877# On Solaris you need to use libsocket for socket ops
878if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
879   if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
880       print "Can't find library with socket calls (e.g. accept())"
881       Exit(1)
882
883# Check for zlib.  If the check passes, libz will be automatically
884# added to the LIBS environment variable.
885if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
886    print 'Error: did not find needed zlib compression library '\
887          'and/or zlib.h header file.'
888    print '       Please install zlib and try again.'
889    Exit(1)
890
891# If we have the protobuf compiler, also make sure we have the
892# development libraries. If the check passes, libprotobuf will be
893# automatically added to the LIBS environment variable. After
894# this, we can use the HAVE_PROTOBUF flag to determine if we have
895# got both protoc and libprotobuf available.
896main['HAVE_PROTOBUF'] = main['PROTOC'] and \
897    conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
898                            'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
899
900# If we have the compiler but not the library, print another warning.
901if main['PROTOC'] and not main['HAVE_PROTOBUF']:
902    print termcap.Yellow + termcap.Bold + \
903        'Warning: did not find protocol buffer library and/or headers.\n' + \
904    '       Please install libprotobuf-dev for tracing support.' + \
905    termcap.Normal
906
907# Check for librt.
908have_posix_clock = \
909    conf.CheckLibWithHeader(None, 'time.h', 'C',
910                            'clock_nanosleep(0,0,NULL,NULL);') or \
911    conf.CheckLibWithHeader('rt', 'time.h', 'C',
912                            'clock_nanosleep(0,0,NULL,NULL);')
913
914if conf.CheckLib('tcmalloc'):
915    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
916elif conf.CheckLib('tcmalloc_minimal'):
917    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
918else:
919    print termcap.Yellow + termcap.Bold + \
920          "You can get a 12% performance improvement by installing tcmalloc "\
921          "(libgoogle-perftools-dev package on Ubuntu or RedHat)." + \
922          termcap.Normal
923
924if not have_posix_clock:
925    print "Can't find library for POSIX clocks."
926
927# Check for <fenv.h> (C99 FP environment control)
928have_fenv = conf.CheckHeader('fenv.h', '<>')
929if not have_fenv:
930    print "Warning: Header file <fenv.h> not found."
931    print "         This host has no IEEE FP rounding mode control."
932
933# Check if we should enable KVM-based hardware virtualization
934have_kvm = conf.CheckHeader('linux/kvm.h', '<>')
935if not have_kvm:
936    print "Info: Header file <linux/kvm.h> not found, " \
937        "disabling KVM support."
938
939# Check if the requested target ISA is compatible with the host
940def is_isa_kvm_compatible(isa):
941    isa_comp_table = {
942        "arm" : ( "armv7l" ),
943        }
944    try:
945        import platform
946        host_isa = platform.machine()
947    except:
948        print "Warning: Failed to determine host ISA."
949        return False
950
951    return host_isa in isa_comp_table.get(isa, [])
952
953
954######################################################################
955#
956# Finish the configuration
957#
958main = conf.Finish()
959
960######################################################################
961#
962# Collect all non-global variables
963#
964
965# Define the universe of supported ISAs
966all_isa_list = [ ]
967Export('all_isa_list')
968
969class CpuModel(object):
970    '''The CpuModel class encapsulates everything the ISA parser needs to
971    know about a particular CPU model.'''
972
973    # Dict of available CPU model objects.  Accessible as CpuModel.dict.
974    dict = {}
975    list = []
976    defaults = []
977
978    # Constructor.  Automatically adds models to CpuModel.dict.
979    def __init__(self, name, filename, includes, strings, default=False):
980        self.name = name           # name of model
981        self.filename = filename   # filename for output exec code
982        self.includes = includes   # include files needed in exec file
983        # The 'strings' dict holds all the per-CPU symbols we can
984        # substitute into templates etc.
985        self.strings = strings
986
987        # This cpu is enabled by default
988        self.default = default
989
990        # Add self to dict
991        if name in CpuModel.dict:
992            raise AttributeError, "CpuModel '%s' already registered" % name
993        CpuModel.dict[name] = self
994        CpuModel.list.append(name)
995
996Export('CpuModel')
997
998# Sticky variables get saved in the variables file so they persist from
999# one invocation to the next (unless overridden, in which case the new
1000# value becomes sticky).
1001sticky_vars = Variables(args=ARGUMENTS)
1002Export('sticky_vars')
1003
1004# Sticky variables that should be exported
1005export_vars = []
1006Export('export_vars')
1007
1008# For Ruby
1009all_protocols = []
1010Export('all_protocols')
1011protocol_dirs = []
1012Export('protocol_dirs')
1013slicc_includes = []
1014Export('slicc_includes')
1015
1016# Walk the tree and execute all SConsopts scripts that wil add to the
1017# above variables
1018if not GetOption('verbose'):
1019    print "Reading SConsopts"
1020for bdir in [ base_dir ] + extras_dir_list:
1021    if not isdir(bdir):
1022        print "Error: directory '%s' does not exist" % bdir
1023        Exit(1)
1024    for root, dirs, files in os.walk(bdir):
1025        if 'SConsopts' in files:
1026            if GetOption('verbose'):
1027                print "Reading", joinpath(root, 'SConsopts')
1028            SConscript(joinpath(root, 'SConsopts'))
1029
1030all_isa_list.sort()
1031
1032sticky_vars.AddVariables(
1033    EnumVariable('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
1034    ListVariable('CPU_MODELS', 'CPU models',
1035                 sorted(n for n,m in CpuModel.dict.iteritems() if m.default),
1036                 sorted(CpuModel.list)),
1037    BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
1038                 False),
1039    BoolVariable('SS_COMPATIBLE_FP',
1040                 'Make floating-point results compatible with SimpleScalar',
1041                 False),
1042    BoolVariable('USE_SSE2',
1043                 'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
1044                 False),
1045    BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
1046    BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
1047    BoolVariable('CP_ANNOTATE', 'Enable critical path annotation capability', False),
1048    BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models', have_kvm),
1049    EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
1050                  all_protocols),
1051    )
1052
1053# These variables get exported to #defines in config/*.hh (see src/SConscript).
1054export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'CP_ANNOTATE',
1055                'USE_POSIX_CLOCK', 'PROTOCOL', 'HAVE_PROTOBUF']
1056
1057###################################################
1058#
1059# Define a SCons builder for configuration flag headers.
1060#
1061###################################################
1062
1063# This function generates a config header file that #defines the
1064# variable symbol to the current variable setting (0 or 1).  The source
1065# operands are the name of the variable and a Value node containing the
1066# value of the variable.
1067def build_config_file(target, source, env):
1068    (variable, value) = [s.get_contents() for s in source]
1069    f = file(str(target[0]), 'w')
1070    print >> f, '#define', variable, value
1071    f.close()
1072    return None
1073
1074# Combine the two functions into a scons Action object.
1075config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1076
1077# The emitter munges the source & target node lists to reflect what
1078# we're really doing.
1079def config_emitter(target, source, env):
1080    # extract variable name from Builder arg
1081    variable = str(target[0])
1082    # True target is config header file
1083    target = joinpath('config', variable.lower() + '.hh')
1084    val = env[variable]
1085    if isinstance(val, bool):
1086        # Force value to 0/1
1087        val = int(val)
1088    elif isinstance(val, str):
1089        val = '"' + val + '"'
1090
1091    # Sources are variable name & value (packaged in SCons Value nodes)
1092    return ([target], [Value(variable), Value(val)])
1093
1094config_builder = Builder(emitter = config_emitter, action = config_action)
1095
1096main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1097
1098# libelf build is shared across all configs in the build root.
1099main.SConscript('ext/libelf/SConscript',
1100                variant_dir = joinpath(build_root, 'libelf'))
1101
1102# gzstream build is shared across all configs in the build root.
1103main.SConscript('ext/gzstream/SConscript',
1104                variant_dir = joinpath(build_root, 'gzstream'))
1105
1106# libfdt build is shared across all configs in the build root.
1107main.SConscript('ext/libfdt/SConscript',
1108                variant_dir = joinpath(build_root, 'libfdt'))
1109
1110###################################################
1111#
1112# This function is used to set up a directory with switching headers
1113#
1114###################################################
1115
1116main['ALL_ISA_LIST'] = all_isa_list
1117def make_switching_dir(dname, switch_headers, env):
1118    # Generate the header.  target[0] is the full path of the output
1119    # header to generate.  'source' is a dummy variable, since we get the
1120    # list of ISAs from env['ALL_ISA_LIST'].
1121    def gen_switch_hdr(target, source, env):
1122        fname = str(target[0])
1123        f = open(fname, 'w')
1124        isa = env['TARGET_ISA'].lower()
1125        print >>f, '#include "%s/%s/%s"' % (dname, isa, basename(fname))
1126        f.close()
1127
1128    # Build SCons Action object. 'varlist' specifies env vars that this
1129    # action depends on; when env['ALL_ISA_LIST'] changes these actions
1130    # should get re-executed.
1131    switch_hdr_action = MakeAction(gen_switch_hdr,
1132                          Transform("GENERATE"), varlist=['ALL_ISA_LIST'])
1133
1134    # Instantiate actions for each header
1135    for hdr in switch_headers:
1136        env.Command(hdr, [], switch_hdr_action)
1137Export('make_switching_dir')
1138
1139###################################################
1140#
1141# Define build environments for selected configurations.
1142#
1143###################################################
1144
1145for variant_path in variant_paths:
1146    print "Building in", variant_path
1147
1148    # Make a copy of the build-root environment to use for this config.
1149    env = main.Clone()
1150    env['BUILDDIR'] = variant_path
1151
1152    # variant_dir is the tail component of build path, and is used to
1153    # determine the build parameters (e.g., 'ALPHA_SE')
1154    (build_root, variant_dir) = splitpath(variant_path)
1155
1156    # Set env variables according to the build directory config.
1157    sticky_vars.files = []
1158    # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1159    # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1160    # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1161    current_vars_file = joinpath(build_root, 'variables', variant_dir)
1162    if isfile(current_vars_file):
1163        sticky_vars.files.append(current_vars_file)
1164        print "Using saved variables file %s" % current_vars_file
1165    else:
1166        # Build dir-specific variables file doesn't exist.
1167
1168        # Make sure the directory is there so we can create it later
1169        opt_dir = dirname(current_vars_file)
1170        if not isdir(opt_dir):
1171            mkdir(opt_dir)
1172
1173        # Get default build variables from source tree.  Variables are
1174        # normally determined by name of $VARIANT_DIR, but can be
1175        # overridden by '--default=' arg on command line.
1176        default = GetOption('default')
1177        opts_dir = joinpath(main.root.abspath, 'build_opts')
1178        if default:
1179            default_vars_files = [joinpath(build_root, 'variables', default),
1180                                  joinpath(opts_dir, default)]
1181        else:
1182            default_vars_files = [joinpath(opts_dir, variant_dir)]
1183        existing_files = filter(isfile, default_vars_files)
1184        if existing_files:
1185            default_vars_file = existing_files[0]
1186            sticky_vars.files.append(default_vars_file)
1187            print "Variables file %s not found,\n  using defaults in %s" \
1188                  % (current_vars_file, default_vars_file)
1189        else:
1190            print "Error: cannot find variables file %s or " \
1191                  "default file(s) %s" \
1192                  % (current_vars_file, ' or '.join(default_vars_files))
1193            Exit(1)
1194
1195    # Apply current variable settings to env
1196    sticky_vars.Update(env)
1197
1198    help_texts["local_vars"] += \
1199        "Build variables for %s:\n" % variant_dir \
1200                 + sticky_vars.GenerateHelpText(env)
1201
1202    # Process variable settings.
1203
1204    if not have_fenv and env['USE_FENV']:
1205        print "Warning: <fenv.h> not available; " \
1206              "forcing USE_FENV to False in", variant_dir + "."
1207        env['USE_FENV'] = False
1208
1209    if not env['USE_FENV']:
1210        print "Warning: No IEEE FP rounding mode control in", variant_dir + "."
1211        print "         FP results may deviate slightly from other platforms."
1212
1213    if env['EFENCE']:
1214        env.Append(LIBS=['efence'])
1215
1216    if env['USE_KVM']:
1217        if not have_kvm:
1218            print "Warning: Can not enable KVM, host seems to lack KVM support"
1219            env['USE_KVM'] = False
1220        elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1221            print "Info: KVM support disabled due to unsupported host and " \
1222                "target ISA combination"
1223            env['USE_KVM'] = False
1224
1225    # Save sticky variable settings back to current variables file
1226    sticky_vars.Save(current_vars_file, env)
1227
1228    if env['USE_SSE2']:
1229        env.Append(CCFLAGS=['-msse2'])
1230
1231    # The src/SConscript file sets up the build rules in 'env' according
1232    # to the configured variables.  It returns a list of environments,
1233    # one for each variant build (debug, opt, etc.)
1234    envList = SConscript('src/SConscript', variant_dir = variant_path,
1235                         exports = 'env')
1236
1237    # Set up the regression tests for each build.
1238    for e in envList:
1239        SConscript('tests/SConscript',
1240                   variant_dir = joinpath(variant_path, 'tests', e.Label),
1241                   exports = { 'env' : e }, duplicate = False)
1242
1243# base help text
1244Help('''
1245Usage: scons [scons options] [build variables] [target(s)]
1246
1247Extra scons options:
1248%(options)s
1249
1250Global build variables:
1251%(global_vars)s
1252
1253%(local_vars)s
1254''' % help_texts)
1255