kconfig migrate: new option to migrate kernel configs

With this option you can run

$ pmbootstrap kconfig migrate --arch <arch> linux-postmarketos-xxx-xxx

to perform safe kconfig upgrades between kernel releases.

"make oldconfig" will ask question for every new/renamed kconfig option,
so you have no chance to miss anything.

pmb/build/menuconfig.py

@@ -78,12 +78,12 @@ def get_outputdir(args, pkgname, apkbuild):
                        " template with: pmbootstrap aportgen " + pkgname)
 
 
-def menuconfig(args, pkgname):
+def menuconfig(args, pkgname, use_oldconfig):
     # Pkgname: allow omitting "linux-" prefix
     if pkgname.startswith("linux-"):
         pkgname_ = pkgname.split("linux-")[1]
-        logging.info("PROTIP: You can simply do 'pmbootstrap kconfig edit " +
-                     pkgname_ + "'")
+        logging.info(f"PROTIP: You can simply do 'pmbootstrap kconfig "
+                     f"{args.action_kconfig} {pkgname_}'")
     else:
         pkgname = "linux-" + pkgname
 
@@ -99,18 +99,24 @@ def menuconfig(args, pkgname):
     pmb.build.init(args, suffix)
     if cross:
         pmb.build.init_compiler(args, [], cross, arch)
+
     depends = apkbuild["makedepends"]
-    kopt = "menuconfig"
     copy_xauth = False
-    if args.xconfig:
-        depends += ["qt5-qtbase-dev", "font-noto"]
-        kopt = "xconfig"
-        copy_xauth = True
-    elif args.nconfig:
-        kopt = "nconfig"
-        depends += ["ncurses-dev"]
+
+    if use_oldconfig:
+        kopt = "oldconfig"
     else:
-        depends += ["ncurses-dev"]
+        kopt = "menuconfig"
+        if args.xconfig:
+            depends += ["qt5-qtbase-dev", "font-noto"]
+            kopt = "xconfig"
+            copy_xauth = True
+        elif args.nconfig:
+            kopt = "nconfig"
+            depends += ["ncurses-dev"]
+        else:
+            depends += ["ncurses-dev"]
+
     pmb.chroot.apk.install(args, depends)
 
     # Copy host's .xauthority into native

pmb/helpers/frontend.py

@@ -417,12 +417,13 @@ def kconfig(args):
                 logging.info("NOTE: " + str(skipped) + " kernel(s) was skipped"
                              " (consider 'pmbootstrap kconfig check -f')")
             logging.info("kconfig check succeeded!")
-    elif args.action_kconfig == "edit":
+    elif args.action_kconfig in ["edit", "migrate"]:
         if args.package:
             pkgname = args.package
         else:
             pkgname = args.deviceinfo["codename"]
-        pmb.build.menuconfig(args, pkgname)
+        use_oldconfig = args.action_kconfig == "migrate"
+        pmb.build.menuconfig(args, pkgname, use_oldconfig)
 
 
 def deviceinfo_parse(args):

pmb/parse/arguments.py

@@ -456,6 +456,17 @@ def arguments_kconfig(subparser):
     if argcomplete:
         edit_package.completer = kernel_completer
 
+    # "pmbootstrap kconfig migrate"
+    migrate = sub.add_parser("migrate",
+                             help="Migrate kconfig from older version to "
+                                  "newer. Internally runs 'make oldconfig', "
+                                  "which asks question for every new kernel "
+                                  "config option.")
+    migrate.add_argument("--arch", choices=arch_choices, dest="arch")
+    migrate_package = migrate.add_argument("package", nargs='?')
+    if argcomplete:
+        migrate_package.completer = kernel_completer
+
 
 def arguments_repo_missing(subparser):
     ret = subparser.add_parser("repo_missing")