################################################################################
  #
  # perf
  #
  ################################################################################
  
  LINUX_TOOLS += perf
  
  PERF_DEPENDENCIES = host-flex host-bison
  
  ifeq ($(KERNEL_ARCH),x86_64)
  PERF_ARCH=x86
  else
  PERF_ARCH=$(KERNEL_ARCH)
  endif
  
  PERF_MAKE_FLAGS = \
  	$(LINUX_MAKE_FLAGS) \
  	JOBS=$(PARALLEL_JOBS) \
  	ARCH=$(PERF_ARCH) \
  	DESTDIR=$(TARGET_DIR) \
  	prefix=/usr \
  	WERROR=0 \
  	NO_LIBAUDIT=1 \
  	NO_NEWT=1 \
  	NO_GTK2=1 \
  	NO_LIBPERL=1 \
  	NO_LIBPYTHON=1 \
  	NO_LIBBIONIC=1
  
  # We need to pass an argument to ld for setting the endianness when
  # building it for MIPS architecture, otherwise the default one will
  # always be used (which is big endian) and the compilation for little
  # endian will always fail showing an error like this one:
  #  LD    foo.o
  # mips-linux-gnu-ld: foo.o: compiled for a little endian system and
  # target is big endian
  ifeq ($(BR2_mips)$(BR2_mips64),y)
  PERF_MAKE_FLAGS += LD="$(TARGET_LD) -EB"
  else ifeq ($(BR2_mipsel)$(BR2_mips64el),y)
  PERF_MAKE_FLAGS += LD="$(TARGET_LD) -EL"
  endif
  
  # The call to backtrace() function fails for ARC, because for some
  # reason the unwinder from libgcc returns early. Thus the usage of
  # backtrace() should be disabled in perf explicitly: at build time
  # backtrace() appears to be available, but it fails at runtime: the
  # backtrace will contain only several functions from the top of stack,
  # instead of the complete backtrace.
  ifeq ($(BR2_arc),y)
  PERF_MAKE_FLAGS += NO_BACKTRACE=1
  endif
  
  ifeq ($(BR2_PACKAGE_SLANG),y)
  PERF_DEPENDENCIES += slang
  else
  PERF_MAKE_FLAGS += NO_SLANG=1
  endif
  
  ifeq ($(BR2_PACKAGE_LIBUNWIND),y)
  PERF_DEPENDENCIES += libunwind
  else
  PERF_MAKE_FLAGS += NO_LIBUNWIND=1
  endif
  
  ifeq ($(BR2_PACKAGE_NUMACTL),y)
  PERF_DEPENDENCIES += numactl
  else
  PERF_MAKE_FLAGS += NO_LIBNUMA=1
  endif
  
  ifeq ($(BR2_PACKAGE_ELFUTILS),y)
  PERF_DEPENDENCIES += elfutils
  else
  PERF_MAKE_FLAGS += NO_LIBELF=1 NO_DWARF=1
  endif
  
  ifeq ($(BR2_PACKAGE_ZLIB),y)
  PERF_DEPENDENCIES += zlib
  else
  PERF_MAKE_FLAGS += NO_ZLIB=1
  endif
  
  # lzma is provided by xz
  ifeq ($(BR2_PACKAGE_XZ),y)
  PERF_DEPENDENCIES += xz
  else
  PERF_MAKE_FLAGS += NO_LZMA=1
  endif
  
  # We really do not want to build the perf documentation, because it
  # has stringent requirement on the documentation generation tools,
  # like xmlto and asciidoc), which may be lagging behind on some
  # distributions.
  # We name it 'GNUmakefile' so that GNU make will use it instead of
  # the existing 'Makefile'.
  define PERF_DISABLE_DOCUMENTATION
  	if [ -f $(@D)/tools/perf/Documentation/Makefile ]; then \
  		printf "%%:
  \t@:
  " >$(@D)/tools/perf/Documentation/GNUmakefile; \
  	fi
  endef
  LINUX_POST_PATCH_HOOKS += PERF_DISABLE_DOCUMENTATION
  
  # O must be redefined here to overwrite the one used by Buildroot for
  # out of tree build. We build perf in $(@D)/tools/perf/ and not just
  # $(@D) so that it isn't built in the root directory of the kernel
  # sources.
  define PERF_BUILD_CMDS
  	$(Q)if test ! -f $(@D)/tools/perf/Makefile ; then \
  		echo "Your kernel version is too old and does not have the perf tool." ; \
  		echo "At least kernel 2.6.31 must be used." ; \
  		exit 1 ; \
  	fi
  	$(Q)if test "$(BR2_PACKAGE_ELFUTILS)" = "" ; then \
  		if ! grep -q NO_LIBELF $(@D)/tools/perf/Makefile* ; then \
  			if ! test -r $(@D)/tools/perf/config/Makefile ; then \
  				echo "The perf tool in your kernel cannot be built without libelf." ; \
  				echo "Either upgrade your kernel to >= 3.7, or enable the elfutils package." ; \
  				exit 1 ; \
  			fi \
  		fi \
  	fi
  	$(TARGET_MAKE_ENV) $(MAKE1) $(PERF_MAKE_FLAGS) \
  		-C $(@D)/tools/perf O=$(@D)/tools/perf/
  endef
  
  # After installation, we remove the Perl and Python scripts from the
  # target.
  define PERF_INSTALL_TARGET_CMDS
  	$(TARGET_MAKE_ENV) $(MAKE1) $(PERF_MAKE_FLAGS) \
  		-C $(@D)/tools/perf O=$(@D)/tools/perf/ install
  	$(RM) -rf $(TARGET_DIR)/usr/libexec/perf-core/scripts/
  	$(RM) -rf $(TARGET_DIR)/usr/libexec/perf-core/tests/
  endef