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scons: Use Kconfig to configure gem5.

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These are not yet consumed by anything, but convert all the settings
from SCons variables to Kconfig variables.

If you have existing SConsopts files which need to be converted, you
should take a look at KCONFIG.md to learn about how kconfig is used in
gem5. You should decide if any variables need to be available to C++ or
kconfig itself, and whether those are options which should be detected
automatically, or should be up to the user. Options which should be
measured automatically should still be in SConsopts files, while user
facing options should be added to new or existing Kconfig files.

Generally, make sure you're storing c++/kconfig visible options in
env['CONF'][...]. Also remove references to sticky_vars since persistent
options should now be handled with kconfig, and export_vars since
everything in env['CONF'] is now exported automatically.

Switch SCons/gem5 to use Kconfig for configuration, except EXTRAS which
is still a sticky SCons variable. This is necessary because EXTRAS also
controls what config options exist. If it came from Kconfig itself, then
there would be a circular dependency. This dependency could
theoretically be handled by reparsing the Kconfig when EXTRAS
directories were added or removed, but that would be complicated, and
isn't supported by kconfiglib. It wouldn't be worth the significant
effort it would take to add it, just to use Kconfig more purely.

Change-Id: I29ab1940b2d7b0e6635a490452d05befe5b4a2c9
This commit is contained in:
Gabe Black
2022-02-16 04:54:22 -08:00
committed by Roger Chang
parent 5f73a9bbf0
commit db3a6e8e84
80 changed files with 925 additions and 370 deletions
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@@ -77,6 +77,7 @@
# Global Python imports
import atexit
import itertools
import os
import sys
@@ -115,8 +116,6 @@ AddOption('--no-colors', dest='use_colors', action='store_false',
help="Don't add color to abbreviated scons output")
AddOption('--with-cxx-config', action='store_true',
help="Build with support for C++-based configuration")
AddOption('--default',
help='Override which build_opts file to use for defaults')
AddOption('--ignore-style', action='store_true',
help='Disable style checking hooks')
AddOption('--linker', action='store', default=None, choices=linker_options,
@@ -162,6 +161,7 @@ sys.path[1:1] = [ Dir('#build_tools').abspath ]
# declared above.
from gem5_scons import error, warning, summarize_warnings, parse_build_path
from gem5_scons import TempFileSpawn, EnvDefaults, MakeAction, MakeActionTool
from gem5_scons import kconfig
import gem5_scons
from gem5_scons.builders import ConfigFile, AddLocalRPATH, SwitchingHeaders
from gem5_scons.builders import Blob
@@ -215,13 +215,6 @@ Default(environ.get('M5_DEFAULT_BINARY', 'build/ARM/gem5.debug'))
#
########################################################################
# helper function: find last occurrence of element in list
def rfind(l, elt, offs = -1):
for i in range(len(l)+offs, 0, -1):
if l[i] == elt:
return i
raise ValueError("element not found")
# Take a list of paths (or SCons Nodes) and return a list with all
# paths made absolute and ~-expanded. Paths will be interpreted
# relative to the launch directory unless a different root is provided
@@ -381,6 +374,10 @@ for variant_path in variant_paths:
env['GEM5BUILD'] = gem5_build
Execute(Mkdir(gem5_build))
config_file = Dir(gem5_build).File('config')
kconfig_file = Dir(gem5_build).File('Kconfig')
gem5_kconfig_file = Dir('#src').File('Kconfig')
env.SConsignFile(os.path.join(gem5_build, 'sconsign'))
# Set up default C++ compiler flags
@@ -662,59 +659,13 @@ for variant_path in variant_paths:
after_sconsopts_callbacks.append(cb)
Export('AfterSConsopts')
# Sticky variables get saved in the variables file so they persist from
# one invocation to the next (unless overridden, in which case the new
# value becomes sticky).
sticky_vars = Variables(args=ARGUMENTS)
Export('sticky_vars')
extras_file = os.path.join(gem5_build, 'extras')
extras_var = Variables(extras_file, args=ARGUMENTS)
# EXTRAS is special since it affects what SConsopts need to be read.
sticky_vars.Add(('EXTRAS', 'Add extra directories to the compilation', ''))
# Set env variables according to the build directory config.
sticky_vars.files = []
# Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
# $BUILD_ROOT/$VARIANT_DIR/gem5.build/variables
gem5_build_vars = os.path.join(gem5_build, 'variables')
build_root_vars = os.path.join(build_root, 'variables', variant_dir)
current_vars_files = [gem5_build_vars, build_root_vars]
existing_vars_files = list(filter(isfile, current_vars_files))
if existing_vars_files:
sticky_vars.files.extend(existing_vars_files)
if not GetOption('silent'):
print('Using saved variables file(s) %s' %
', '.join(existing_vars_files))
else:
# Variant specific variables file doesn't exist.
# Get default build variables from source tree. Variables are
# normally determined by name of $VARIANT_DIR, but can be
# overridden by '--default=' arg on command line.
default = GetOption('default')
opts_dir = Dir('#build_opts').abspath
if default:
default_vars_files = [
gem5_build_vars,
build_root_vars,
os.path.join(opts_dir, default)
]
else:
default_vars_files = [os.path.join(opts_dir, variant_dir)]
existing_default_files = list(filter(isfile, default_vars_files))
if existing_default_files:
default_vars_file = existing_default_files[0]
sticky_vars.files.append(default_vars_file)
print("Variables file(s) %s not found,\n using defaults in %s" %
(' or '.join(current_vars_files), default_vars_file))
else:
error("Cannot find variables file(s) %s or default file(s) %s" %
(' or '.join(current_vars_files),
' or '.join(default_vars_files)))
Exit(1)
extras_var.Add(('EXTRAS', 'Add extra directories to the compilation', ''))
# Apply current settings for EXTRAS to env.
sticky_vars.Update(env)
extras_var.Update(env)
# Parse EXTRAS variable to build list of all directories where we're
# look for sources etc. This list is exported as extras_dir_list.
@@ -725,6 +676,17 @@ for variant_path in variant_paths:
Export('extras_dir_list')
# Generate a Kconfig that will source the main gem5 one, and any in any
# EXTRAS directories.
kconfig_base_py = Dir('#build_tools').File('kconfig_base.py')
kconfig_base_cmd_parts = [f'"{kconfig_base_py}" "{kconfig_file.abspath}"',
f'"{gem5_kconfig_file.abspath}"']
for ed in extras_dir_list:
kconfig_base_cmd_parts.append(f'"{ed}"')
kconfig_base_cmd = ' '.join(kconfig_base_cmd_parts)
if env.Execute(kconfig_base_cmd) != 0:
error("Failed to build base Kconfig file")
# Variables which were determined with Configure.
env['CONF'] = {}
@@ -752,24 +714,15 @@ for variant_path in variant_paths:
for cb in after_sconsopts_callbacks:
cb()
# Update env for new variables added by the SConsopts.
sticky_vars.Update(env)
# If no config exists yet, see if we know how to make one?
if not isfile(config_file.abspath):
buildopts_file = Dir('#build_opts').File(variant_dir)
if not isfile(buildopts_file.abspath):
error('No config found, and no implicit config recognized')
kconfig.defconfig(env, kconfig_file.abspath, buildopts_file.abspath,
config_file.abspath)
Help('''
Build variables for {dir}:
{help}
'''.format(dir=variant_dir, help=sticky_vars.GenerateHelpText(env)),
append=True)
# If the old vars file exists, delete it to avoid confusion/stale values.
if isfile(build_root_vars):
warning(f'Deleting old variant variables file "{build_root_vars}"')
remove(build_root_vars)
# Save sticky variables back to the gem5.build variant variables file.
sticky_vars.Save(gem5_build_vars, env)
# Pull all the sticky variables into the CONF dict.
env['CONF'].update({key: env[key] for key in sticky_vars.keys()})
kconfig.update_env(env, kconfig_file.abspath, config_file.abspath)
# Do this after we save setting back, or else we'll tack on an
# extra 'qdo' every time we run scons.