# $Id: Makefile-header.gmk 77740 2019-03-17 03:03:50Z vboxsync $
## @file
# VirtualBox Guest Additions kernel module Makefile, common parts.
#
# (For 2.6.x, the main file must be called 'Makefile'!)
#

#
# Copyright (C) 2006-2019 Oracle Corporation
#
# This file is part of VirtualBox Open Source Edition (OSE), as
# available from http://www.virtualbox.org. This file is free software;
# you can redistribute it and/or modify it under the terms of the GNU
# General Public License (GPL) as published by the Free Software
# Foundation, in version 2 as it comes in the "COPYING" file of the
# VirtualBox OSE distribution. VirtualBox OSE is distributed in the
# hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
#

# 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
#
# The kmk kBuild define KBUILD_TARGET_ARCH is available.
#


#
# 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.
#
ifeq ($(filter-out x86_64 amd64 AMD64,$(shell uname -m)),)
 BUILD_TARGET_ARCH_DEF := amd64
else
 BUILD_TARGET_ARCH_DEF := x86
endif
ifneq ($(filter-out amd64 x86,$(BUILD_TARGET_ARCH)),)
 $(warning Ignoring unknown BUILD_TARGET_ARCH value '$(BUILD_TARGET_ARCH)'.)
 BUILD_TARGET_ARCH :=
endif
ifeq ($(BUILD_TARGET_ARCH),)
 ifeq ($(ARCH),x86_64)
  BUILD_TARGET_ARCH := amd64
 else
  ifeq ($(ARCH),i386)
   BUILD_TARGET_ARCH := x86
  else
   BUILD_TARGET_ARCH := $(BUILD_TARGET_ARCH_DEF)
  endif
 endif
else
 ifneq ($(BUILD_TARGET_ARCH),$(BUILD_TARGET_ARCH_DEF))
  $(warning Using BUILD_TARGET_ARCH='$(BUILD_TARGET_ARCH)' from the $(origin BUILD_TARGET_ARCH).)
 endif
endif

ifneq ($(filter-out release profile debug strict,$(BUILD_TYPE)),)
 $(warning Ignoring unknown BUILD_TYPE value '$(BUILD_TYPE)'.)
 BUILD_TYPE :=
endif
ifeq ($(BUILD_TYPE),)
 BUILD_TYPE := release
else
 ifneq ($(BUILD_TYPE),release)
  ifndef VBOX_KERN_QUIET
   $(warning Using BUILD_TYPE='$(BUILD_TYPE)' from the $(origin BUILD_TYPE).)
  endif
 endif
endif
ifeq ($(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
 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 ($(KERN_DIR),)
  KERN_DIR := /lib/modules/$(KERN_VER)/build
 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)

#
# The KBUILD_EXTMOD variable is used by 2.6.6 and later when build external
# modules (see https://lwn.net/Articles/79984/).  It will be set to SUBDIRS
# or M by the linux kernel makefile.  We fake it here for older kernels.
#
## @todo Drop this KBUILD_EXTMOD glue once it has been removed from all our makefiles (see sharedfolders).
ifndef CURDIR # for make < v3.79
 CURDIR := $(shell pwd)
endif
ifndef KBUILD_EXTMOD
 KBUILD_EXTMOD := $(CURDIR)
endif


# 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.
#
ifdef MAKEFILE_LIST
 VBOX_MODULE_SRC_DIR := $(dir $(word $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)))
else
 VBOX_MODULE_SRC_DIR := $(CURDIR)/
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: KBUILD_EXTMOD    = $(KBUILD_EXTMOD))
$(warning dbg: VBOX_MODULE_SRC_DIR = $(VBOX_MODULE_SRC_DIR))
 endif
endif