dry run for all common

README.adoc

@@ -3787,6 +3787,8 @@ although this can be useful when someone gives you a random image.
 
 TODO: explain link:update-buildroot-kernel-config[]
 
+TODO: mention `--dry-run`
+
 TODO Beware that Buildroot can `sed` override some of the configurations we make no matter what, e.g. it forces `CONFIG_BLK_DEV_INITRD=y` when `BR2_TARGET_ROOTFS_CPIO` is on, so you might want to double check as explained at <<find-the-kernel-config>>. TODO check if there is a way to prevent that patching and maybe patch Buildroot for it, it is too fuzzy. People should be able to just build with whatever `.config` they want.
 
 We have managed to come up with minimalistic kernel configs that work for both QEMU and gem5 (oh, the hours of bisection).

build

@@ -153,9 +153,7 @@ passing this option multiple times. Default: [{}]
 '''.format(common.default_arch))
 for component in component_names:
     add_bool_arg(parser, component)
-parser.add_argument('--dry-run', default=False, action='store_true', help='''\
+common.add_dry_run_argument(parser)
-Print the commands that would be run, but don't run them.
-''')
 args = parser.parse_args()
 
 # Decide archs.

build-linux

@@ -20,7 +20,8 @@ args = common.setup(parser)
 if args.clean:
     common.rmrf(common.linux_build_dir)
 else:
-    start_time = time.time()
+    if not common.dry_run:
+        start_time = time.time()
     os.makedirs(common.linux_build_dir, exist_ok=True)
     shutil.copy2(
         os.path.join(common.linux_config_dir, 'buildroot-{}'.format(args.arch)),
@@ -82,5 +83,6 @@ else:
         ),
         **common_args,
     ) == 0
-    end_time = time.time()
+    if not common.dry_run:
-    common.print_time(end_time - start_time)
+        end_time = time.time()
+        common.print_time(end_time - start_time)

common.py

@@ -80,6 +80,11 @@ def add_build_arguments(parser):
         action='store_true',
     )
 
+def add_dry_run_argument(parser):
+    parser.add_argument('--dry-run', default=False, action='store_true', help='''\
+    Print the commands that would be run, but don't run them.
+''')
+
 def base64_encode(string):
     return base64.b64encode(string.encode()).decode()
 
@@ -122,6 +127,7 @@ def get_argparse(default_args=None, argparse_args=None):
         formatter_class=argparse.RawTextHelpFormatter,
         **argparse_args
     )
+    this.add_dry_run_argument(parser)
     parser.add_argument(
         '-a', '--arch', choices=this.arch_choices, default=this.default_arch,
         help='CPU architecture. Default: %(default)s'
@@ -508,7 +514,7 @@ def run_cmd(
     #sigpipe_old = signal.getsignal(signal.SIGPIPE)
     #signal.signal(signal.SIGPIPE, signal.SIG_DFL)
 
-    if not dry_run:
+    if not dry_run and not this.dry_run:
         # https://stackoverflow.com/questions/15535240/python-popen-write-to-stdout-and-log-file-simultaneously/52090802#52090802
         with subprocess.Popen(cmd, stdout=stdout, stderr=stderr, env=env, **kwargs) as proc:
             if out_file is not None:
@@ -550,6 +556,7 @@ def setup(parser):
     if args.gem5_worktree is not None and not gem5_build_id_given:
         args.gem5_build_id = args.gem5_worktree
     this.machine = args.machine
+    this.dry_run = args.dry_run
     if args.arch == 'arm':
         this.armv = 7
         this.gem5_arch = 'ARM'