gem5: replace --gem5-src with --gem5-worktree-path

README.adoc

@@ -10667,32 +10667,28 @@ Even removing remotes is not safe enough, since `git submodule update` and other
 
 Instead, we provide the following safer process.
 
-First do a separate private clone of you private repository:
+First do a separate private clone of you private repository outside of this repository:
 
 ....
 git clone https://my.private.repo.com/my-fork/gem5.git gem5-internal
 gem5_internal="$(pwd)/gem5-internal"
 ....
 
-Next, when you want to build with this repository, use the `--gem5-src` argument to point this repository to the private source code:
+Next, when you want to build with this repository, use the `--gem5-worktree-path` argument to point this repository to the private source code:
 
 ....
 cd linux-kernel-module-cheat
 ./build-gem5 \
   --gem5-build-id private/master \
-  --gem5-src "$gem5_internal" \
-  --gem5-worktree private/master \
+  --gem5-worktree-path "$gem5_internal" \
 ;
 ./run-gem5
   --gem5-build-id private/master \
-  --gem5-src "$gem5_internal" \
-  --gem5-worktree private/master \
+  --gem5-worktree-path "$gem5_internal" \
 ;
 ....
 
-`private` is not mandatory, but it is a sane default that will remind you at all times that you are dealing with private code instead of public.
-
-This setup only creates gitignored worktrees of the private repository inside this repository, which is pretty safe, while still allowing fully use our infrastructure as usual.
+With this setup, only the private gem5 build outputs are stored in this repository, and they are safely gitignored.
 
 ===== gem5 debug build
 

build-gem5

@@ -27,16 +27,17 @@ else:
     start_time = time.time()
     os.makedirs(binaries_dir, exist_ok=True)
     os.makedirs(disks_dir, exist_ok=True)
-    if  not os.path.exists(os.path.join(common.gem5_src_dir, '.git')):
-        if common.gem5_src_dir == common.gem5_default_src_dir:
-            raise Exception('gem5 submodule not checked out')
-        assert common.run_cmd([
-            'git',
-            '-C', common.gem5_default_src_dir,
-            'worktree', 'add',
-            '-b', os.path.join('wt', args.gem5_build_id),
-            common.gem5_src_dir
-        ]) == 0
+    if args.gem5_src is None:
+        if not os.path.exists(os.path.join(common.gem5_src_dir, '.git')):
+            if common.gem5_src_dir == common.gem5_default_src_dir:
+                raise Exception('gem5 submodule not checked out')
+            assert common.run_cmd([
+                'git',
+                '-C', common.gem5_default_src_dir,
+                'worktree', 'add',
+                '-b', os.path.join('wt', args.gem5_build_id),
+                common.gem5_src_dir
+            ]) == 0
     if args.arch == 'x86_64':
         dummy_img_path = os.path.join(disks_dir, 'linux-bigswap2.img')
         with open(dummy_img_path, 'wb') as dummy_img_file:

common.py

@@ -125,16 +125,18 @@ See the documentation for other values known to work.
         '-M', '--gem5-build-id', default=default_build_id,
         help='gem5 build ID. Allows you to keep multiple separate gem5 builds. Default: %(default)s'
     )
-    parser.add_argument(
-        '--gem5-src',
-        help='If given, use the gem5 directory exactly as submodules/gem5 is would normally used.'
-    )
     parser.add_argument(
         '-N', '--gem5-worktree',
         help='''\
 gem5 git worktree to use for build and Python scripts at runtime. Automatically
 create a new git worktree with the given id if one does not exist. If not
 given, just use the submodule source.
+'''
+    )
+    parser.add_argument(
+        '--gem5-src',
+        help='''\
+Use the given directory as the gem5 source tree. Ignore `--gem5-worktree`.
 '''
     )
     parser.add_argument(
@@ -528,14 +530,15 @@ def setup(parser):
     this.crosstool_ng_executable = os.path.join(this.crosstool_ng_util_dir, 'ct-ng')
     this.crosstool_ng_build_dir = os.path.join(this.crosstool_ng_buildid_dir, 'build')
     this.crosstool_ng_download_dir = os.path.join(this.crosstool_ng_out_dir, 'download')
-    if (args.gem5_src):
-        this.gem5_default_src_dir = args.gem5_src
+    this.gem5_default_src_dir = os.path.join(submodules_dir, 'gem5')
+    if args.gem5_src is not None:
+        this.gem5_src_dir = args.gem5_src
+        assert(os.path.exists(args.gem5_src))
     else:
-        this.gem5_default_src_dir = os.path.join(submodules_dir, 'gem5')
-    if args.gem5_worktree is not None:
-        this.gem5_src_dir = os.path.join(this.gem5_non_default_src_root_dir, args.gem5_worktree)
-    else:
-        this.gem5_src_dir = this.gem5_default_src_dir
+        if args.gem5_worktree is not None:
+            this.gem5_src_dir = os.path.join(this.gem5_non_default_src_root_dir, args.gem5_worktree)
+        else:
+            this.gem5_src_dir = this.gem5_default_src_dir
     if args.gem5:
         this.executable = this.gem5_executable
         this.run_dir = this.gem5_run_dir