#
# KBUILD Makefile for the NVIDIA Linux kernel module.
#
# The motivation for replacing the original Makefile is the hope that this
# version will simplify the build and installation process. In the past,
# many architectural and cosmetic changes to the Linux kernel have made it
# difficult to maintain compatibility or required duplication of logic.
#
# Linux 2.5 introduces numerous such changes, many of which impact modules.
# Relying on KBUILD, some aspects of the build system otherwise difficult
# to support (for example, module versioning) are abstracted away and dealt
# with elsewhere, making life significantly easier here.
#
# The new approach currently has its own share of problems, some of which
# are architectural difficulties with KBUILD, others minor annoyances. For
# this reason, an improved version of the NVIDIA Makefile is available to
# those experiencing difficulties.
#
# Please report any problems you may be experiencing with this experimental
# Makefile to either one (or, preferably, both) of us:
#
# Alistair J Strachan (alistair@devzero.co.uk) (first pass, enhancements)
# Christian Zander (zander@email.minion.de) (enhancements)
#

all: install
install: package-install

#
# The NVIDIA kernel module base name and static file names. KBUILD will go
# ahead and append ".o" or ".ko" to form the final module name.
#

MODULE_NAME := nvidia
VERSION_HEADER := nv_compiler.h

#
# List of object files to link into NVIDIA kernel module; make sure KBUILD
# understands that we want a module.
#

RESMAN_CORE_OBJS := nv-kernel.o
RESMAN_GLUE_OBJS := nv.o os-agp.o os-interface.o os-registry.o

$(MODULE_NAME)-objs := $(RESMAN_CORE_OBJS) $(RESMAN_GLUE_OBJS)

#
# A bug in KBUILD 2.4 means that leaving obj-m set in top-level context
# will cause Rules.make to call pathdown.sh, which is wrong. So, we only
# set this conditional of a kernel-level instance.
#

ifdef TOPDIR
obj-m += $(MODULE_NAME).o
endif

#
# Include local source directory in $(CC)'s include path and set disable any
# warning types that are of little interest to us.
#

EXTRA_CFLAGS += -I$(src)
EXTRA_CFLAGS += -Wno-cast-qual -Wno-strict-prototypes

#
# Determine location of the Linux kernel source tree. Allow users to override
# the default (i.e. automatically determined) kernel source location with the
# KERNDIR directive; this new directive replaces NVIDIA's SYSINCLUDE.
#

ifdef KERNDIR
  KERNEL_SOURCES := $(KERNDIR)
  KERNEL_HEADERS := -I$(KERNEL_SOURCES)/include
  MODULE_ROOT    := /lib/modules/$(shell uname -r)/kernel/drivers # XXX
else
  KERNEL_SOURCES := /lib/modules/$(shell uname -r)/build
  KERNEL_HEADERS := -I$(KERNEL_SOURCES)/include
  MODULE_ROOT    := /lib/modules/$(shell uname -r)/kernel/drivers
endif

#
# We rely on these two definitions below; if they aren't set, we set them to
# reasonable defaults (Linux 2.4's KBUILD, and top-level passes will not set
# these).
#

src ?= .
obj ?= .

#
# Sets any internal variables left unset by KBUILD (e.g. this happens during
# a top-level run).
#

TOPDIR ?= $(KERNEL_SOURCES)
PATCHLEVEL ?= $(shell sh $(src)/conftest.sh kernel_patch_level $(TOPDIR))

#
# Linux 2.4 uses the .o module extension. Linux 2.5, however, uses the .ko
# module extension. Handle these gracefully.
#

ifeq ($(PATCHLEVEL), 4)
  MODULE_OBJECT := $(MODULE_NAME).o
else
  MODULE_OBJECT := $(MODULE_NAME).ko
endif

#
# NVIDIA specific CFLAGS and #define's. The remap_page_range check has become
# necessary with the introduction of the five argument version to Linux 2.4
# distribution kernels; this conflicting change cannot be detected at compile
# time.
#

EXTRA_CFLAGS += -DNTRM -D_LOOSE_KERNEL_NAMES -D__KERNEL__ -DMODULE  -DNV_MAJOR_VERSION=1 -DNV_MINOR_VERSION=0 -DNV_PATCHLEVEL=4348  -DNV_UNIX   -DNV_LINUX   -DNV_INT64_OK   -DNVCPU_X86

ifeq ($(shell echo $(NVDEBUG)),1)
  ifeq ($(shell test -z $(RMDEBUG) && echo yes),yes)
    RMDEBUG=1
  endif
endif

ifeq ($(shell echo $(RMDEBUG)),1)
  EXTRA_CFLAGS += -DDEBUG -g -fno-common
endif

ifeq ($(shell sh $(src)/conftest.sh remap_page_range $(KERNEL_HEADERS)), 5)
  EXTRA_CFLAGS += -DREMAP_PAGE_RANGE_5
endif

ifeq ($(shell sh $(src)/conftest.sh remap_page_range $(KERNEL_HEADERS)), 4)
  EXTRA_CFLAGS += -DREMAP_PAGE_RANGE_4
endif

#
# NVIDIA binary object file includes .common section.
#

EXTRA_LDFLAGS := -d

#
# Miscellaneous NVIDIA kernel module build support targets. They are needed
# to satisfy KBUILD requirements and to support NVIDIA specifics.
#

$(obj)/nv-kernel.o:
	cp $(src)/$(RESMAN_CORE_OBJS) $(obj)/$(RESMAN_CORE_OBJS)

$(obj)/$(VERSION_HEADER):
	echo \#define NV_COMPILER \"`$(CC) -v 2>&1 | tail -1`\" > $@

$(obj)/nv.o: $(obj)/$(VERSION_HEADER)

#
# More quirks for Linux 2.4 KBUILD, which doesn't link automatically.
#

ifeq ($(PATCHLEVEL), 4)
$(obj)/$(MODULE_NAME).o: $($(MODULE_NAME)-objs)
	$(LD) $(EXTRA_LDFLAGS) -r -o $@ $($(MODULE_NAME)-objs)
endif

#
# KBUILD build parameters.
#

KBUILD_PARAMS := -C $(KERNEL_SOURCES) SUBDIRS=$(PWD)

#
# NVIDIA sanity checks.
#

suser-sanity-check:
	@if ! sh conftest.sh suser_sanity_check; then \
	  echo; \
	  echo "You have insufficient privileges for this operation. Please "; \
	  echo "run \"make install\" as root!                               "; \
	  echo; \
	  exit 1; \
	fi

rmmod-sanity-check:
	@if ! sh conftest.sh rmmod_sanity_check $(MODULE_NAME); then \
	  echo; \
	  echo "Unable to unload the currently loaded NVIDIA kernel module! "; \
	  echo "Please be certain that you have exited X before attempting  "; \
	  echo "to install this version.                                    "; \
	  echo; \
	  exit 1; \
	fi

cc-sanity-check:
	@if ! sh conftest.sh cc_sanity_check $(CC); then \
	  echo; \
	  echo "You appear to be building the NVIDIA kernel module with a  "; \
	  echo "compiler different from the one that was used to build the "; \
	  echo "running kernel. This may be perfectly fine, but there are  "; \
	  echo "cases where this can lead to unexpected behaviour and      "; \
	  echo "system crashes.                                            "; \
	  echo; \
	  echo "If you know what you are doing and want to override this   "; \
	  echo "check, you can do so by setting IGNORE_CC_MISMATCH.        "; \
	  echo; \
	  echo "In any other case, set the CC environment variable to the  "; \
	  echo "name of the compiler that was used to build the kernel.    "; \
	  echo; \
	  exit 1; \
	fi

#
# Build the NVIDIA kernel module using Linux KBUILD. This target is used by
# the "package-install" target below.
#

module: cc-sanity-check
	@make $(KBUILD_PARAMS) modules; \
	if ! [ -f $(MODULE_OBJECT) ]; then \
	  echo "$(MODULE_OBJECT) failed to build!"; \
	  exit 1; \
	fi

#
# Build the NVIDIA kernel module with KBUILD. Verify that the user posesses
# sufficient privileges. Rebuild the module dependency file.
#

module-install: suser-sanity-check module
	@mkdir -p $(MODULE_ROOT)/video; \
	install -m 0664 -o root -g root $(MODULE_OBJECT) $(MODULE_ROOT)/video; \
	/sbin/depmod -ae;

#
# This target builds, then installs, then creates device nodes and inserts
# the module, if successful.
#

package-install: module-install rmmod-sanity-check
	@sh makedevices.sh; \
	/sbin/modprobe $(MODULE_NAME) && \
	echo "$(MODULE_OBJECT) installed successfully.";

#
# Support hack, KBUILD isn't prepared to clean up after external modules.
#

clean:
	@rm -f $(RESMAN_GLUE_OBJS) .*.{cmd,flags}
	@rm -f $(MODULE_NAME).{o,ko,mod.{o,c}} built-in.o $(VERSION_HEADER) *~

#
# Linux 2.4 KBUILD requires the inclusion of Rules.make; Linux 2.5's KBUILD
# includes dependencies automatically.
#

ifeq ($(PATCHLEVEL), 4)
include $(KERNEL_SOURCES)/Rules.make
endif