# $Id: Makefile-header.gmk $
## @file
# VirtualBox Guest Additions kernel module Makefile, common parts.
#
# (For 2.6.x, the main file must be called 'Makefile'!)
#

#
# Copyright (C) 2006-2023 Oracle and/or its affiliates.
#
# This file is part of VirtualBox base platform packages, as
# available from https://www.virtualbox.org.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation, in version 3 of the
# License.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, see <https://www.gnu.org/licenses>.
#
# SPDX-License-Identifier: GPL-3.0-only
#

# Testing:
# * Building with KERN_DIR set uses the value specified and
#   the default value for the unspecified one if any.

#
# These file should be included by the Makefiles for any kernel modules we
# build as part of the Guest Additions.  The intended way of doing this is as
# follows:
#
# # Linux kbuild sets this to our source directory if we are called from there
# obj ?= $(CURDIR)
# include $(obj)/Makefile-header.gmk
# VBOXMOD_NAME = <name of the module to be built, without extension>
# VBOXMOD_OBJS = <list of object files which should be included>
# VBOXMOD_DEFS = <any additional defines which this module needs>
# VBOXMOD_INCL = <any additional include paths which this module needs>
# VBOXMOD_CFLAGS = <any additional CFLAGS which this module needs>
# include $(obj)/Makefile-footer.gmk
#
# To avoid potential confusion between kmk/kBuild and linux/kbuild,
# we use VBOX_KBUILD_TARGET_ARCH instead of KBUILD_TARGET_ARCH and
# VBOX_KBUILD_TYPE instead of KBUILD_TYPE.  The VBOX_KBUILD_ variable
# variant takes percedence over the kmk/kBuild ones.
#


#
# First, figure out which architecture we're targeting and the build type.
# (We have to support basic cross building (ARCH=i386|x86_64).)
# While at it, warn about *BUILD_* vars found to help with user problems.
#

# VBOX_KBUILD_TARGET_ARCH = amd64|x86
ifeq ($(filter-out x86_64 amd64 AMD64,$(shell uname -m)),)
 VBOX_KBUILD_TARGET_ARCH_DEFAULT := amd64
else
 VBOX_KBUILD_TARGET_ARCH_DEFAULT := x86
endif
ifdef VBOX_KBUILD_TARGET_ARCH
 ifneq ($(filter-out amd64 x86,$(VBOX_KBUILD_TARGET_ARCH)),)
  $(warning Ignoring unknown VBOX_KBUILD_TARGET_ARCH value '$(VBOX_KBUILD_TARGET_ARCH)'.)
  VBOX_KBUILD_TARGET_ARCH :=
 endif
else
 ifdef KBUILD_TARGET_ARCH
  ifneq ($(filter-out amd64 x86,$(KBUILD_TARGET_ARCH)),)
  $(warning Ignoring unknown KBUILD_TARGET_ARCH value '$(KBUILD_TARGET_ARCH)'.)
  VBOX_KBUILD_TARGET_ARCH :=
  endif
  else
   ifdef BUILD_TARGET_ARCH
    $(warning BUILD_TARGET_ARCH is deprecated, use VBOX_KBUILD_TARGET_ARCH instead.)
    ifneq ($(filter-out amd64 x86,$(BUILD_TARGET_ARCH)),)
     $(warning Ignoring unknown BUILD_TARGET_ARCH value '$(BUILD_TARGET_ARCH)'.)
     VBOX_KBUILD_TARGET_ARCH :=
   endif
  endif
 endif
endif
ifeq ($(VBOX_KBUILD_TARGET_ARCH),)
 ifeq ($(ARCH),x86_64)
  VBOX_KBUILD_TARGET_ARCH := amd64
 else
  ifeq ($(ARCH),i386)
   VBOX_KBUILD_TARGET_ARCH := x86
  else
   VBOX_KBUILD_TARGET_ARCH := $(VBOX_KBUILD_TARGET_ARCH_DEFAULT)
  endif
 endif
else
 ifneq ($(VBOX_KBUILD_TARGET_ARCH),$(VBOX_KBUILD_TARGET_ARCH_DEFAULT))
  $(warning Using VBOX_KBUILD_TARGET_ARCH='$(VBOX_KBUILD_TARGET_ARCH)' from the $(origin VBOX_KBUILD_TARGET_ARCH).)
 endif
endif

# VBOX_KBUILD_TYPE = release|debug|profile|strict|asan
ifdef VBOX_KBUILD_TYPE
 VBOX_KBUILD_TYPE_VAR := VBOX_KBUILD_TYPE
 ifneq ($(filter-out release profile debug strict asan,$(VBOX_KBUILD_TYPE)),)
  $(warning Ignoring unknown VBOX_KBUILD_TYPE value '$(VBOX_KBUILD_TYPE)'.)
  VBOX_KBUILD_TYPE :=
 endif
else
 ifdef KBUILD_TYPE
  VBOX_KBUILD_TYPE_VAR := KBUILD_TYPE
  VBOX_KBUILD_TYPE := $(KBUILD_TYPE)
  ifneq ($(filter-out release profile debug strict asan,$(KBUILD_TYPE)),)
   $(warning Ignoring unknown KBUILD_TYPE value '$(KBUILD_TYPE)'.)
   VBOX_KBUILD_TYPE :=
  endif
 else
  ifdef BUILD_TYPE
   $(warning BUILD_TYPE is deprecated, use VBOX_KBUILD_TYPE instead.)
   VBOX_KBUILD_TYPE_VAR := BUILD_TYPE
   VBOX_KBUILD_TYPE := $(BUILD_TYPE)
   ifneq ($(filter-out release profile debug strict asan,$(BUILD_TYPE)),)
    $(warning Ignoring unknown BUILD_TYPE value '$(BUILD_TYPE)'.)
    VBOX_KBUILD_TYPE :=
   endif
  endif
 endif
endif
ifeq ($(VBOX_KBUILD_TYPE),)
 VBOX_KBUILD_TYPE_VAR = VBOX_KBUILD_TYPE
 VBOX_KBUILD_TYPE := release
else
 ifneq ($(VBOX_KBUILD_TYPE),release)
  ifndef VBOX_KERN_QUIET
   $(warning Using VBOX_KBUILD_TYPE='$(VBOX_KBUILD_TYPE)' from the $(origin $(VBOX_KBUILD_TYPE_VAR)) ($(VBOX_KBUILD_TYPE_VAR)).)
  endif
 endif
endif

ifeq ($(USERNAME),)
 USERNAME := noname
endif

ifeq ($(KERNELRELEASE),)

 #
 # building from this directory
 #

 # kernel base directory
 ifdef KERN_DIR
  ifndef KERN_VER
   ifeq ($(filter %/build,$(KERN_DIR)),)
    $(error The variable KERN_DIR must be a kernel build folder and end with /build without a trailing slash, or KERN_VER must be set)
   endif
  endif
 endif

 ifndef KERN_VER
  ifdef KERN_DIR
   KERN_VER = $(notdir $(patsubst %/build,%,$(KERN_DIR)))
   ifeq ($(shell expr $(KERN_VER) : '[0-9]*\.[0-9]*.[0-9]*'),0)
    $(error The kernel build folder path must end in <version>/build, or the variable KERN_VER must be set)
   endif
  endif
  KERN_VER ?= $(shell uname -r)
 endif

 ifeq ($(KERN_DIR),)
  KERN_DIR := /lib/modules/$(KERN_VER)/build
 endif

 # Is this 2.4 or < 2.6.6? The UTS_RELEASE "2.x.y.z" define is present in the header until 2.6.1x something.
 ifeq ($(shell if grep '"2\.4\.' $(KERN_DIR)/include/linux/version.h > /dev/null 2>&1; then echo yes; fi),yes)
  KERN_VERSION := 24
  VBOX_KERN_GROKS_EXTMOD :=
 else
  KERN_VERSION := 26
  VBOX_KERN_GROKS_EXTMOD := yes
  ifeq ($(shell if grep '"2\.6\.[012345][."]' $(KERN_DIR)/include/linux/version.h > /dev/null 2>&1; then echo yes; fi),yes)
   VBOX_KERN_GROKS_EXTMOD :=
  endif
  VBOX_KERN_GROKS_SUBDIRS  :=
  ifeq ($(shell if grep '"[432]\.' $(KERN_DIR)/include/linux/version.h > /dev/null 2>&1; then echo yes; fi),yes)
   VBOX_KERN_GROKS_SUBDIRS := yes
  endif
 endif

 #
 # Hack for Ubuntu 4.10 where we determine 2.6.8.1-3-generic-amd64 here, but the
 # the next invocation (M/SUBDIR) ends up with KERNELRELEASE=2.6.8.1-3.
 #
 ifeq ($(shell if grep '"[2]\.' $(KERN_DIR)/include/linux/version.h > /dev/null 2>&1; then echo yes; fi),yes)
  export KERN_VER KERN_DIR
 else
  # This makefile received some variables in the command line which should
  # not be passed to the recursive make invocations (of the Linux makefile
  # for building kernel modules), since they should derive KERN_DIR from the
  # respective command line variables to come up with the value they expect.
  unexport KERN_VER KERN_DIR
  MAKEOVERRIDES := $(filter-out KERN_VER=% KERN_DIR=%,$(MAKEOVERRIDES))
 endif

else # neq($(KERNELRELEASE),)

 #
 # building from kbuild (make -C <kernel_directory> M=`pwd`)
 #

 # guess kernel version (24 or 26)
 ifeq ($(VERSION).$(PATCHLEVEL),2.4)
  KERN_VERSION := 24
  VBOX_KERN_GROKS_EXTMOD :=
 else
  KERN_VERSION := 26
  VBOX_KERN_GROKS_EXTMOD := yes
  ifeq ($(VERSION).$(PATCHLEVEL),2.6)
   ifeq ($(findstring @$(SUBLEVEL)@,@0@1@2@3@4@5@),@$(SUBLEVEL)@)
    VBOX_KERN_GROKS_EXTMOD :=
   endif
  endif
  VBOX_KERN_GROKS_SUBDIRS  :=
  ifeq ($(VERSION),2)
   VBOX_KERN_GROKS_SUBDIRS := yes
  endif
  ifeq ($(VERSION),3)
   VBOX_KERN_GROKS_SUBDIRS := yes
  endif
  ifeq ($(VERSION),4)
   VBOX_KERN_GROKS_SUBDIRS := yes
  endif
 endif

 KERN_VER := $(KERNELRELEASE)

 ifeq ($(KERN_DIR),)
  ifneq ($(srctree),)
   KERN_DIR := $(srctree)
  else
   KERN_DIR := /lib/modules/$(KERN_VER)/build
  endif
 endif
endif # neq($(KERNELRELEASE),)

# Kernel build folder
ifneq ($(shell if test -d $(KERN_DIR); then echo yes; fi),yes)
 $(error Error: unable to find the headers of the Linux kernel to build against (KERN_DIR=$(KERN_DIR)). \
          Specify KERN_VER=<version> (currently $(KERN_VER)) and run Make again)
endif
# Kernel include folder
KERN_INCL := $(KERN_DIR)/include
# module install folder
INSTALL_MOD_DIR ?= misc
MODULE_DIR := $(INSTALL_MOD_PATH)/lib/modules/$(KERN_VER)/$(INSTALL_MOD_DIR)

# For VBOX_GCC_CHECK_CC
VBOX_CLOSEPAR := )
VBOX_DOLLAR   := $$
## Modified VBOX_GCC_CHECK_EX_CC_CXX macro from /Config.kmk.
# @param 1 The option to test for.
# @param 2 The return value when supported.
# @param 3 The return value when NOT supported.
VBOX_GCC_CHECK_CC = $(shell \
    > /tmp/$(VBOX_DOLLAR)$(VBOX_DOLLAR).check.c; \
    if $(CC) $(subst -Wno-,-W,$(1)) -Werror -c -o /dev/null /tmp/$(VBOX_DOLLAR)$(VBOX_DOLLAR).check.c > /dev/null 2>&1; then \
        case "`LC_ALL=C $(CC) $(subst -Wno-,-W,$(1)) -Werror -c -o /dev/null /tmp/$(VBOX_DOLLAR)$(VBOX_DOLLAR).check.c 2>&1`" in \
            "error: unknown warning option"*$(VBOX_CLOSEPAR) echo "$(3)";; \
            *$(VBOX_CLOSEPAR) echo "$(2)";; \
         esac; \
    else echo "$(3)"; fi; \
    rm -f /tmp/$(VBOX_DOLLAR)$(VBOX_DOLLAR).check.c; )

#
# Guess the module directory ASSUMING that this file is located in that directory.
# Note! The special MAKEFILE_LIST variable was introduced in GNU make 3.80.
#
ifndef VBOX_MODULE_SRC_DIR
 ifdef MAKEFILE_LIST
  VBOX_MODULE_SRC_DIR := $(dir $(word $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)))
 else
  VBOX_MODULE_SRC_DIR := $(CURDIR)/
 endif
endif


# debug - show guesses.
ifdef DEBUG
 ifndef VBOX_KERN_QUIET
$(warning dbg: INSTALL_MOD_PATH = $(INSTALL_MOD_PATH))
$(warning dbg: INSTALL_MOD_DIR  = $(INSTALL_MOD_DIR))
$(warning dbg: KERN_DIR         = $(KERN_DIR))
$(warning dbg: KERN_INCL        = $(KERN_INCL))
$(warning dbg: KERN_VERSION     = $(KERN_VERSION))
$(warning dbg: MODULE_DIR       = $(MODULE_DIR))
$(warning dbg: VBOX_MODULE_SRC_DIR = $(VBOX_MODULE_SRC_DIR))
 endif
endif