kconfig: support board-specific defconfig

The current defconfigs are BIOS-specific which makes it difficult to maintain
multiple defconfigs for boards running the same BIOS.

This patch re-organizes the defconfigs to be board-specific. A command line
option BOARD is introduced to specify a board on which the current build targets
at. The original PLATFORM is kept for backward compatibility which redirects to
apl-mrb and nuc6cayh for sbl and uefi, respectively.

The getting started guide is also updated accordingly.

v1 -> v2:

* Rewrite 'up2' to 'UP2'.

Tracked-On: #1588
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Reviewed-by: Anthony Xu <anthony.xu@intel.com>

doc/getting-started/apl-nuc.rst

@@ -254,7 +254,7 @@ partition. Follow these steps:
 
       # systemctl enable weston@cl_sos
       # systemctl start weston@cl_sos
-      
+
 #. Reboot and select "The ACRN Service OS" to boot, as shown below:
 
 
@@ -537,7 +537,7 @@ The build results are found in the ``build`` directory.
 .. note::
    if you wish to use a different target folder for the build
    artefacts, set the ``O`` (that is capital letter 'O') to the
-   desired value. Example: ``make O=build-uefi PLATFORM=uefi``.
+   desired value. Example: ``make O=build-nuc BOARD=nuc6cayh``.
 
 Generating the documentation is decribed in details in the :ref:`acrn_doc`
 tutorial.
@@ -551,7 +551,7 @@ and are using it as the current working directory.
    .. code-block:: none
 
       $ cd hypervisor
-      $ make PLATFORM=uefi
+      $ make BOARD=nuc6cayh
 
    The build results are found in the ``build`` directory.
 
@@ -578,8 +578,8 @@ Generate the hypervisor configurations
 ======================================
 
 The ACRN hypervisor leverages Kconfig to manage configurations, powered by
-Kconfiglib. A default configuration is generated based on the platform you have
-selected via the ``PLATFORM=`` command line parameter. You can make further
+Kconfiglib. A default configuration is generated based on the board you have
+selected via the ``BOARD=`` command line parameter. You can make further
 changes to that default configuration to adjust to your specific
 requirements.
 
@@ -592,9 +592,9 @@ found under the target folder of your build.
    .. code-block:: none
 
       $ cd hypervisor
-      $ make defconfig PLATFORM=uefi
+      $ make defconfig BOARD=nuc6cayh
 
-The PLATFORM specified is used to select a defconfig under
+The BOARD specified is used to select a defconfig under
 ``arch/x86/configs/``. The other command-line based options (e.g. ``RELEASE``)
 take no effects when generating a defconfig.
 
@@ -611,7 +611,7 @@ the hypervisor using the updated ``.config``.
    .. code-block:: none
 
       $ cd hypervisor
-      $ make defconfig PLATFORM=uefi
+      $ make defconfig BOARD=nuc6cayh
       $ make menuconfig              # Modify the configurations per your needs
       $ make                         # Build the hypervisor with the new .config
 
@@ -628,21 +628,21 @@ Create a new default configuration
 ==================================
 
 Currently the ACRN hypervisor looks for default configurations under
-``hypervisor/arch/x86/configs/<PLATFORM>.config``, where ``<PLATFORM>`` is the
+``hypervisor/arch/x86/configs/<BOARD>.config``, where ``<BOARD>`` is the
 specified platform. The following steps allow you to create a defconfig for
 another platform based on a current one.
 
    .. code-block:: none
 
       $ cd hypervisor
-      $ make defconfig PLATFORM=uefi
+      $ make defconfig BOARD=nuc6cayh
       $ make menuconfig         # Modify the configurations
       $ make savedefconfig      # The minimized config reside at build/defconfig
       $ cp build/defconfig arch/x86/configs/xxx.config
 
 Then you can re-use that configuration by passing the name (``xxx`` in the
-example above) to 'PLATFORM=':
+example above) to 'BOARD=':
 
    .. code-block:: none
 
-      $ make defconfig PLATFORM=xxx
+      $ make defconfig BOARD=xxx

hypervisor/arch/x86/Kconfig

@@ -45,6 +45,16 @@ config PLATFORM
 	default "uefi" if PLATFORM_UEFI
 	default "sbl" if PLATFORM_SBL
 
+config BOARD
+	string "Target board"
+	help
+	The target board this build runs on top of.
+
+config DEFCONFIG_LIST
+	string
+	option defconfig_list
+	default "arch/x86/configs/$BOARD.config"
+
 config RELEASE
 	bool "Release build"
 	default n

hypervisor/arch/x86/configs/apl-mrb.config

@@ -1,2 +1,3 @@
+CONFIG_BOARD="apl-mrb"
 # CONFIG_PLATFORM_UEFI is not set
 CONFIG_PLATFORM_SBL=y

hypervisor/arch/x86/configs/apl-nuc.config

@@ -0,0 +1 @@
+nuc6cayh.config

hypervisor/arch/x86/configs/nuc6cayh.config

@@ -0,0 +1,3 @@
+CONFIG_BOARD="NUC6CAYH"
+CONFIG_PLATFORM_UEFI=y
+# CONFIG_PLATFORM_SBL is not set

hypervisor/arch/x86/configs/up2.config

@@ -1,2 +1,3 @@
+CONFIG_BOARD="UP2"
 CONFIG_PLATFORM_UEFI=y
 # CONFIG_PLATFORM_SBL is not set

hypervisor/scripts/kconfig/kconfig.mk

@@ -30,9 +30,27 @@ endif
 endif
 
 -include $(HV_OBJDIR)/$(HV_CONFIG_MK)
-$(eval $(call override_config,PLATFORM,sbl))
+
+# Backward-compatibility for PLATFORM=(sbl|uefi)
+# * PLATFORM=sbl is equivalent to BOARD=apl-mrb
+# * PLATFORM=uefi is equivalent to BOARD=apl-nuc (i.e. NUC6CAYH)
+ifndef BOARD
+ifeq ($(PLATFORM),sbl)
+BOARD=apl-mrb
+else ifeq ($(PLATFORM),uefi)
+BOARD=apl-nuc
+endif
+endif
+
+$(eval $(call override_config,BOARD,apl-mrb))
 $(eval $(call override_config,RELEASE,n))
 
+ifdef BOARD
+TARGET_BOARD=$(BOARD)
+else
+TARGET_BOARD=$(CONFIG_BOARD)
+endif
+
 $(eval $(call check_dep_exec,python3,KCONFIG_DEPS))
 $(eval $(call check_dep_py3lib,kconfiglib,KCONFIG_DEPS))
 
@@ -59,8 +77,8 @@ $(HV_OBJDIR)/$(HV_CONFIG_H): $(HV_OBJDIR)/$(HV_CONFIG)
 .PHONY: defconfig
 defconfig: $(KCONFIG_DEPS)
 	@mkdir -p $(HV_OBJDIR)
-	@python3 $(KCONFIG_DIR)/defconfig.py Kconfig \
-		arch/x86/configs/$(CONFIG_PLATFORM).config \
+	@BOARD=$(TARGET_BOARD) \
+	 python3 $(KCONFIG_DIR)/defconfig.py Kconfig \
 		$(HV_OBJDIR)/$(HV_CONFIG)
 
 # Use silentoldconfig to forcefully update the current .config, or generate a
@@ -73,9 +91,9 @@ defconfig: $(KCONFIG_DEPS)
 .PHONY: oldconfig
 oldconfig: $(KCONFIG_DEPS)
 	@mkdir -p $(HV_OBJDIR)
-	@python3 $(KCONFIG_DIR)/silentoldconfig.py Kconfig \
+	@BOARD=$(TARGET_BOARD) \
+	 python3 $(KCONFIG_DIR)/silentoldconfig.py Kconfig \
 		$(HV_OBJDIR)/$(HV_CONFIG) \
-		PLATFORM_$(shell echo $(PLATFORM) | tr a-z A-Z)=y \
 		RELEASE=$(RELEASE)
 
 # Minimize the current .config. This target can be used to generate a defconfig

scripts/kconfig/defconfig.py

@@ -12,28 +12,45 @@ import sys, os
 import kconfiglib
 
 def usage():
-    sys.stdout.write("%s: <Kconfig file> <defconfig> <path to .config>\n" % sys.argv[0])
+    sys.stdout.write("%s: <Kconfig file> <path to .config>\n" % sys.argv[0])
 
 def main():
-    if len(sys.argv) < 4:
+    if len(sys.argv) < 3:
         usage()
         sys.exit(1)
 
+    target_board = os.environ['BOARD']
+
     kconfig_path = sys.argv[1]
     if not os.path.isfile(kconfig_path):
         sys.stderr.write("Cannot find file %s\n" % kconfig_path)
         sys.exit(1)
 
-    defconfig_path = sys.argv[2]
-    if not os.path.isfile(defconfig_path):
-        sys.stderr.write("Cannot find file %s\n" % defconfig_path)
+    kconfig = kconfiglib.Kconfig(kconfig_path)
+    defconfig_path = kconfig.defconfig_filename
+    if not defconfig_path or not os.path.isfile(defconfig_path):
+        sys.stderr.write("No defconfig found for board %s.\n" % target_board)
         sys.exit(1)
 
-    sys.stdout.write("Default configuration based on %s.\n" % defconfig_path)
-    kconfig = kconfiglib.Kconfig(kconfig_path)
     kconfig.load_config(defconfig_path)
-    kconfig.write_config(sys.argv[3])
-    sys.stdout.write("Configuration written to %s.\n" % sys.argv[3])
+
+    config_path = sys.argv[2]
+    if os.path.isfile(config_path):
+        # No need to change .config if it is already equivalent to the specified
+        # default.
+        kconfig_current = kconfiglib.Kconfig(kconfig_path)
+        kconfig_current.load_config(config_path)
+        same_config = True
+        for sym in kconfig_current.syms:
+            if kconfig_current.syms[sym].str_value != kconfig.syms[sym].str_value:
+                same_config = False
+                break
+        if same_config:
+            sys.exit(0)
+
+    sys.stdout.write("Default configuration based on %s.\n" % defconfig_path)
+    kconfig.write_config(config_path)
+    sys.stdout.write("Configuration written to %s.\n" % config_path)
 
 if __name__ == "__main__":
     main()