meta/classes/kernel-yocto.bbclass - stefanberger/openbmc - Gitiles

 # remove tasks that modify the source tree in case externalsrc is inherited
 SRCTREECOVEREDTASKS += "do_kernel_link_vmlinux do_kernel_configme do_validate_branches do_kernel_configcheck do_kernel_checkout do_shared_workdir do_fetch do_unpack do_patch"

 # returns local (absolute) path names for all valid patches in the
 # src_uri
 def find_patches(d):
     patches = src_patches(d)
     patch_list=[]
     for p in patches:
         _, _, local, _, _, _ = bb.fetch.decodeurl(p)
         patch_list.append(local)

     return patch_list

 # returns all the elements from the src uri that are .scc files
 def find_sccs(d):
     sources=src_patches(d, True)
     sources_list=[]
     for s in sources:
         base, ext = os.path.splitext(os.path.basename(s))
         if ext and ext in [".scc", ".cfg"]:
             sources_list.append(s)
         elif base and base in 'defconfig':
             sources_list.append(s)

     return sources_list

 # check the SRC_URI for "kmeta" type'd git repositories. Return the name of
 # the repository as it will be found in WORKDIR
 def find_kernel_feature_dirs(d):
     feature_dirs=[]
     fetch = bb.fetch2.Fetch([], d)
     for url in fetch.urls:
         urldata = fetch.ud[url]
         parm = urldata.parm
         type=""
         if "type" in parm:
             type = parm["type"]
         if "destsuffix" in parm:
             destdir = parm["destsuffix"]
             if type == "kmeta":
                 feature_dirs.append(destdir)

     return feature_dirs

 # find the master/machine source branch. In the same way that the fetcher proceses
 # git repositories in the SRC_URI we take the first repo found, first branch.
 def get_machine_branch(d, default):
     fetch = bb.fetch2.Fetch([], d)
     for url in fetch.urls:
         urldata = fetch.ud[url]
         parm = urldata.parm
         if "branch" in parm:
             branches = urldata.parm.get("branch").split(',')
             btype = urldata.parm.get("type")
             if btype != "kmeta":
                 return branches[0]

     return default

 do_kernel_metadata() {
 	set +e
 	cd ${S}
 	export KMETA=${KMETA}

 	# if kernel tools are available in-tree, they are preferred
 	# and are placed on the path before any external tools. Unless
 	# the external tools flag is set, in that case we do nothing.
 	if [ -f "${S}/scripts/util/configme" ]; then
 		if [ -z "${EXTERNAL_KERNEL_TOOLS}" ]; then
 			PATH=${S}/scripts/util:${PATH}
 		fi
 	fi

 	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"
 	machine_srcrev="${SRCREV_machine}"
 	if [ -z "${machine_srcrev}" ]; then
 		# fallback to SRCREV if a non machine_meta tree is being built
 		machine_srcrev="${SRCREV}"
 	fi

 	# In a similar manner to the kernel itself:
 	#
 	#   defconfig: $(obj)/conf
 	#   ifeq ($(KBUILD_DEFCONFIG),)
 	#	$< --defconfig $(Kconfig)
 	#   else
 	#	@echo "*** Default configuration is based on '$(KBUILD_DEFCONFIG)'"
 	#	$(Q)$< --defconfig=arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG) $(Kconfig)
 	#   endif
 	#
 	# If a defconfig is specified via the KBUILD_DEFCONFIG variable, we copy it
 	# from the source tree, into a common location and normalized "defconfig" name,
 	# where the rest of the process will include and incoroporate it into the build
 	#
 	# If the fetcher has already placed a defconfig in WORKDIR (from the SRC_URI),
 	# we don't overwrite it, but instead warn the user that SRC_URI defconfigs take
 	# precendence.
 	#
 	if [ -n "${KBUILD_DEFCONFIG}" ]; then
 		if [ -f "${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG}" ]; then
 			if [ -f "${WORKDIR}/defconfig" ]; then
 				# If the two defconfig's are different, warn that we didn't overwrite the
 				# one already placed in WORKDIR by the fetcher.
 				cmp "${WORKDIR}/defconfig" "${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG}"
 				if [ $? -ne 0 ]; then
 					bbwarn "defconfig detected in WORKDIR. ${KBUILD_DEFCONFIG} skipped"
 				fi
 			else
 				cp -f ${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG} ${WORKDIR}/defconfig
 				sccs="${WORKDIR}/defconfig"
 			fi
 		else
 			bbfatal "A KBUILD_DECONFIG '${KBUILD_DEFCONFIG}' was specified, but not present in the source tree"
 		fi
 	fi

 	sccs="$sccs ${@" ".join(find_sccs(d))}"
 	patches="${@" ".join(find_patches(d))}"
 	feat_dirs="${@" ".join(find_kernel_feature_dirs(d))}"

 	# add any explicitly referenced features onto the end of the feature
 	# list that is passed to the kernel build scripts.
 	if [ -n "${KERNEL_FEATURES}" ]; then
 		for feat in ${KERNEL_FEATURES}; do
 			addon_features="$addon_features --feature $feat"
 		done
 	fi

 	# check for feature directories/repos/branches that were part of the
 	# SRC_URI. If they were supplied, we convert them into include directives
 	# for the update part of the process
 	if [ -n "${feat_dirs}" ]; then
 	    for f in ${feat_dirs}; do
 		if [ -d "${WORKDIR}/$f/meta" ]; then
 		    includes="$includes -I${WORKDIR}/$f/meta"
 		elif [ -d "${WORKDIR}/$f" ]; then
 		    includes="$includes -I${WORKDIR}/$f"
 		fi
 	    done
 	fi

 	# updates or generates the target description
 	updateme ${updateme_flags} -DKDESC=${KMACHINE}:${LINUX_KERNEL_TYPE} \
                          ${includes} ${addon_features} ${ARCH} ${KMACHINE} ${sccs} ${patches}
 	if [ $? -ne 0 ]; then
 		bbfatal_log "Could not update ${machine_branch}"
 	fi
 }

 do_patch() {
 	cd ${S}

 	# executes and modifies the source tree as required
 	patchme ${KMACHINE}
 	if [ $? -ne 0 ]; then
 		bberror "Could not apply patches for ${KMACHINE}."
 		bbfatal_log "Patch failures can be resolved in the linux source directory ${S})"
 	fi

 	# check to see if the specified SRCREV is reachable from the final branch.
 	# if it wasn't something wrong has happened, and we should error.
 	machine_srcrev="${SRCREV_machine}"
 	if [ -z "${machine_srcrev}" ]; then
 		# fallback to SRCREV if a non machine_meta tree is being built
 		machine_srcrev="${SRCREV}"
 		# if SRCREV cannot be reached something is wrong.
 		if [ -z "${machine_srcrev}" ]; then
 			bbfatal "Neither SRCREV_machine or SRCREV was specified!"
 		fi
 	fi

 	if [ "${machine_srcrev}" != "AUTOINC" ]; then
 		if ! [ "$(git rev-parse --verify ${machine_srcrev}~0)" = "$(git merge-base ${machine_srcrev} HEAD)" ]; then
 			bberror "SRCREV ${machine_srcrev} was specified, but is not reachable"
 			bbfatal "Check the BSP description for incorrect branch selection, or other errors."
 		fi
 	fi
 }

 do_kernel_checkout() {
 	set +e

 	source_dir=`echo ${S} | sed 's%/$%%'`
 	source_workdir="${WORKDIR}/git"
 	if [ -d "${WORKDIR}/git/" ]; then
 		# case: git repository
 		# if S is WORKDIR/git, then we shouldn't be moving or deleting the tree.
 		if [ "${source_dir}" != "${source_workdir}" ]; then
 			if [ -d "${source_workdir}/.git" ]; then
 				# regular git repository with .git
 				rm -rf ${S}
 				mv ${WORKDIR}/git ${S}
 			else
 				# create source for bare cloned git repository
 				git clone ${WORKDIR}/git ${S}
 				rm -rf ${WORKDIR}/git
 			fi
 		fi
 		cd ${S}
 	else
 		# case: we have no git repository at all.
 		# To support low bandwidth options for building the kernel, we'll just
 		# convert the tree to a git repo and let the rest of the process work unchanged

 		# if ${S} hasn't been set to the proper subdirectory a default of "linux" is
 		# used, but we can't initialize that empty directory. So check it and throw a
 		# clear error

 	        cd ${S}
 		if [ ! -f "Makefile" ]; then
 			bberror "S is not set to the linux source directory. Check "
 			bbfatal "the recipe and set S to the proper extracted subdirectory"
 		fi
 		rm -f .gitignore
 		git init
 		git add .
 		git commit -q -m "baseline commit: creating repo for ${PN}-${PV}"
 		git clean -d -f
 	fi

 	# convert any remote branches to local tracking ones
 	for i in `git branch -a --no-color | grep remotes | grep -v HEAD`; do
 		b=`echo $i | cut -d' ' -f2 | sed 's%remotes/origin/%%'`;
 		git show-ref --quiet --verify -- "refs/heads/$b"
 		if [ $? -ne 0 ]; then
 			git branch $b $i > /dev/null
 		fi
 	done

 	# Create a working tree copy of the kernel by checking out a branch
 	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"

 	# checkout and clobber any unimportant files
 	git checkout -f ${machine_branch}
 }
 do_kernel_checkout[dirs] = "${S}"

 addtask kernel_checkout before do_kernel_metadata after do_unpack
 addtask kernel_metadata after do_validate_branches do_unpack before do_patch
 do_kernel_metadata[depends] = "kern-tools-native:do_populate_sysroot"

 do_kernel_configme[dirs] += "${S} ${B}"
 do_kernel_configme() {
 	bbnote "kernel configme"
 	export KMETA=${KMETA}

 	if [ -n "${KCONFIG_MODE}" ]; then
 		configmeflags=${KCONFIG_MODE}
 	else
 		# If a defconfig was passed, use =n as the baseline, which is achieved
 		# via --allnoconfig
 		if [ -f ${WORKDIR}/defconfig ]; then
 			configmeflags="--allnoconfig"
 		fi
 	fi

 	cd ${S}
 	PATH=${PATH}:${S}/scripts/util
 	configme ${configmeflags} --reconfig --output ${B} ${LINUX_KERNEL_TYPE} ${KMACHINE}
 	if [ $? -ne 0 ]; then
 		bbfatal_log "Could not configure ${KMACHINE}-${LINUX_KERNEL_TYPE}"
 	fi

 	echo "# Global settings from linux recipe" >> ${B}/.config
 	echo "CONFIG_LOCALVERSION="\"${LINUX_VERSION_EXTENSION}\" >> ${B}/.config
 }

 addtask kernel_configme before do_configure after do_patch

 python do_kernel_configcheck() {
     import re, string, sys

     # if KMETA isn't set globally by a recipe using this routine, we need to
     # set the default to 'meta'. Otherwise, kconf_check is not passed a valid
     # meta-series for processing
     kmeta = d.getVar( "KMETA", True ) or "meta"
     if not os.path.exists(kmeta):
         kmeta = "." + kmeta

     pathprefix = "export PATH=%s:%s; " % (d.getVar('PATH', True), "${S}/scripts/util/")
     cmd = d.expand("cd ${S}; kconf_check -config %s/meta-series ${S} ${B}" % kmeta)
     ret, result = oe.utils.getstatusoutput("%s%s" % (pathprefix, cmd))

     config_check_visibility = int(d.getVar( "KCONF_AUDIT_LEVEL", True ) or 0)
     bsp_check_visibility = int(d.getVar( "KCONF_BSP_AUDIT_LEVEL", True ) or 0)

     # if config check visibility is non-zero, report dropped configuration values
     mismatch_file = "${S}/" + kmeta + "/" + "mismatch.cfg"
     if os.path.exists(mismatch_file):
         if config_check_visibility:
             with open (mismatch_file, "r") as myfile:
                 results = myfile.read()
                 bb.warn( "[kernel config]: specified values did not make it into the kernel's final configuration:\n\n%s" % results)

     # if config check visibility is level 2 or higher, report non-hardware options
     nonhw_file = "${S}/" + kmeta + "/" + "nonhw_report.cfg"
     if os.path.exists(nonhw_file):
         if config_check_visibility > 1:
             with open (nonhw_file, "r") as myfile:
                 results = myfile.read()
                 bb.warn( "[kernel config]: BSP specified non-hw configuration:\n\n%s" % results)

     bsp_desc = "${S}/" + kmeta + "/" + "top_tgt"
     if os.path.exists(bsp_desc) and bsp_check_visibility > 1:
         with open (bsp_desc, "r") as myfile:
             bsp_tgt = myfile.read()
             m = re.match("^(.*)scratch.obj(.*)$", bsp_tgt)
             if not m is None:
                 bb.warn( "[kernel]: An auto generated BSP description was used, this normally indicates a misconfiguration.\n" +
                          "Check that your machine (%s) has an associated kernel description." % "${MACHINE}" )
 }

 # Ensure that the branches (BSP and meta) are on the locations specified by
 # their SRCREV values. If they are NOT on the right commits, the branches
 # are corrected to the proper commit.
 do_validate_branches() {
 	set +e
 	cd ${S}

 	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"
 	machine_srcrev="${SRCREV_machine}"

 	# if SRCREV is AUTOREV it shows up as AUTOINC there's nothing to
 	# check and we can exit early
 	if [ "${machine_srcrev}" = "AUTOINC" ]; then
 		bbnote "SRCREV validation is not required for AUTOREV"
 	elif [ "${machine_srcrev}" = "" ]; then
 		if [ "${SRCREV}" != "AUTOINC" ] && [ "${SRCREV}" != "INVALID" ]; then
 		       # SRCREV_machine_<MACHINE> was not set. This means that a custom recipe
 		       # that doesn't use the SRCREV_FORMAT "machine_meta" is being built. In
 		       # this case, we need to reset to the give SRCREV before heading to patching
 		       bbnote "custom recipe is being built, forcing SRCREV to ${SRCREV}"
 		       force_srcrev="${SRCREV}"
 		fi
 	else
 		git cat-file -t ${machine_srcrev} > /dev/null
 		if [ $? -ne 0 ]; then
 			bberror "${machine_srcrev} is not a valid commit ID."
 			bbfatal_log "The kernel source tree may be out of sync"
 		fi
 		force_srcrev=${machine_srcrev}
 	fi

 	git checkout -q -f ${machine_branch}
 	if [ -n "${force_srcrev}" ]; then
 		# see if the branch we are about to patch has been properly reset to the defined
 		# SRCREV .. if not, we reset it.
 		branch_head=`git rev-parse HEAD`
 		if [ "${force_srcrev}" != "${branch_head}" ]; then
 			current_branch=`git rev-parse --abbrev-ref HEAD`
 			git branch "$current_branch-orig"
 			git reset --hard ${force_srcrev}
 		fi
 	fi
 }

 # Many scripts want to look in arch/$arch/boot for the bootable
 # image. This poses a problem for vmlinux based booting. This
 # task arranges to have vmlinux appear in the normalized directory
 # location.
 do_kernel_link_vmlinux() {
 	if [ ! -d "${B}/arch/${ARCH}/boot" ]; then
 		mkdir ${B}/arch/${ARCH}/boot
 	fi
 	cd ${B}/arch/${ARCH}/boot
 	ln -sf ../../../vmlinux
 }

 OE_TERMINAL_EXPORTS += "KBUILD_OUTPUT"
 KBUILD_OUTPUT = "${B}"

 python () {
     # If diffconfig is available, ensure it runs after kernel_configme
     if 'do_diffconfig' in d:
         bb.build.addtask('do_diffconfig', None, 'do_kernel_configme', d)
 }
	# remove tasks that modify the source tree in case externalsrc is inherited
	SRCTREECOVEREDTASKS += "do_kernel_link_vmlinux do_kernel_configme do_validate_branches do_kernel_configcheck do_kernel_checkout do_shared_workdir do_fetch do_unpack do_patch"

	# returns local (absolute) path names for all valid patches in the
	# src_uri
	def find_patches(d):
	patches = src_patches(d)
	patch_list=[]
	for p in patches:
	_, _, local, _, _, _ = bb.fetch.decodeurl(p)
	patch_list.append(local)

	return patch_list

	# returns all the elements from the src uri that are .scc files
	def find_sccs(d):
	sources=src_patches(d, True)
	sources_list=[]
	for s in sources:
	base, ext = os.path.splitext(os.path.basename(s))
	if ext and ext in [".scc", ".cfg"]:
	sources_list.append(s)
	elif base and base in 'defconfig':
	sources_list.append(s)

	return sources_list

	# check the SRC_URI for "kmeta" type'd git repositories. Return the name of
	# the repository as it will be found in WORKDIR
	def find_kernel_feature_dirs(d):
	feature_dirs=[]
	fetch = bb.fetch2.Fetch([], d)
	for url in fetch.urls:
	urldata = fetch.ud[url]
	parm = urldata.parm
	type=""
	if "type" in parm:
	type = parm["type"]
	if "destsuffix" in parm:
	destdir = parm["destsuffix"]
	if type == "kmeta":
	feature_dirs.append(destdir)

	return feature_dirs

	# find the master/machine source branch. In the same way that the fetcher proceses
	# git repositories in the SRC_URI we take the first repo found, first branch.
	def get_machine_branch(d, default):
	fetch = bb.fetch2.Fetch([], d)
	for url in fetch.urls:
	urldata = fetch.ud[url]
	parm = urldata.parm
	if "branch" in parm:
	branches = urldata.parm.get("branch").split(',')
	btype = urldata.parm.get("type")
	if btype != "kmeta":
	return branches[0]

	return default

	do_kernel_metadata() {
	set +e
	cd ${S}
	export KMETA=${KMETA}

	# if kernel tools are available in-tree, they are preferred
	# and are placed on the path before any external tools. Unless
	# the external tools flag is set, in that case we do nothing.
	if [ -f "${S}/scripts/util/configme" ]; then
	if [ -z "${EXTERNAL_KERNEL_TOOLS}" ]; then
	PATH=${S}/scripts/util:${PATH}
	fi
	fi

	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"
	machine_srcrev="${SRCREV_machine}"
	if [ -z "${machine_srcrev}" ]; then
	# fallback to SRCREV if a non machine_meta tree is being built
	machine_srcrev="${SRCREV}"
	fi

	# In a similar manner to the kernel itself:
	#
	# defconfig: $(obj)/conf
	# ifeq ($(KBUILD_DEFCONFIG),)
	# $< --defconfig $(Kconfig)
	# else
	# @echo "*** Default configuration is based on '$(KBUILD_DEFCONFIG)'"
	# $(Q)$< --defconfig=arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG) $(Kconfig)
	# endif
	#
	# If a defconfig is specified via the KBUILD_DEFCONFIG variable, we copy it
	# from the source tree, into a common location and normalized "defconfig" name,
	# where the rest of the process will include and incoroporate it into the build
	#
	# If the fetcher has already placed a defconfig in WORKDIR (from the SRC_URI),
	# we don't overwrite it, but instead warn the user that SRC_URI defconfigs take
	# precendence.
	#
	if [ -n "${KBUILD_DEFCONFIG}" ]; then
	if [ -f "${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG}" ]; then
	if [ -f "${WORKDIR}/defconfig" ]; then
	# If the two defconfig's are different, warn that we didn't overwrite the
	# one already placed in WORKDIR by the fetcher.
	cmp "${WORKDIR}/defconfig" "${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG}"
	if [ $? -ne 0 ]; then
	bbwarn "defconfig detected in WORKDIR. ${KBUILD_DEFCONFIG} skipped"
	fi
	else
	cp -f ${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG} ${WORKDIR}/defconfig
	sccs="${WORKDIR}/defconfig"
	fi
	else
	bbfatal "A KBUILD_DECONFIG '${KBUILD_DEFCONFIG}' was specified, but not present in the source tree"
	fi
	fi

	sccs="$sccs ${@" ".join(find_sccs(d))}"
	patches="${@" ".join(find_patches(d))}"
	feat_dirs="${@" ".join(find_kernel_feature_dirs(d))}"

	# add any explicitly referenced features onto the end of the feature
	# list that is passed to the kernel build scripts.
	if [ -n "${KERNEL_FEATURES}" ]; then
	for feat in ${KERNEL_FEATURES}; do
	addon_features="$addon_features --feature $feat"
	done
	fi

	# check for feature directories/repos/branches that were part of the
	# SRC_URI. If they were supplied, we convert them into include directives
	# for the update part of the process
	if [ -n "${feat_dirs}" ]; then
	for f in ${feat_dirs}; do
	if [ -d "${WORKDIR}/$f/meta" ]; then
	includes="$includes -I${WORKDIR}/$f/meta"
	elif [ -d "${WORKDIR}/$f" ]; then
	includes="$includes -I${WORKDIR}/$f"
	fi
	done
	fi

	# updates or generates the target description
	updateme ${updateme_flags} -DKDESC=${KMACHINE}:${LINUX_KERNEL_TYPE} \
	${includes} ${addon_features} ${ARCH} ${KMACHINE} ${sccs} ${patches}
	if [ $? -ne 0 ]; then
	bbfatal_log "Could not update ${machine_branch}"
	fi
	}

	do_patch() {
	cd ${S}

	# executes and modifies the source tree as required
	patchme ${KMACHINE}
	if [ $? -ne 0 ]; then
	bberror "Could not apply patches for ${KMACHINE}."
	bbfatal_log "Patch failures can be resolved in the linux source directory ${S})"
	fi

	# check to see if the specified SRCREV is reachable from the final branch.
	# if it wasn't something wrong has happened, and we should error.
	machine_srcrev="${SRCREV_machine}"
	if [ -z "${machine_srcrev}" ]; then
	# fallback to SRCREV if a non machine_meta tree is being built
	machine_srcrev="${SRCREV}"
	# if SRCREV cannot be reached something is wrong.
	if [ -z "${machine_srcrev}" ]; then
	bbfatal "Neither SRCREV_machine or SRCREV was specified!"
	fi
	fi

	if [ "${machine_srcrev}" != "AUTOINC" ]; then
	if ! [ "$(git rev-parse --verify ${machine_srcrev}~0)" = "$(git merge-base ${machine_srcrev} HEAD)" ]; then
	bberror "SRCREV ${machine_srcrev} was specified, but is not reachable"
	bbfatal "Check the BSP description for incorrect branch selection, or other errors."
	fi
	fi
	}

	do_kernel_checkout() {
	set +e

	source_dir=`echo ${S} \| sed 's%/$%%'`
	source_workdir="${WORKDIR}/git"
	if [ -d "${WORKDIR}/git/" ]; then
	# case: git repository
	# if S is WORKDIR/git, then we shouldn't be moving or deleting the tree.
	if [ "${source_dir}" != "${source_workdir}" ]; then
	if [ -d "${source_workdir}/.git" ]; then
	# regular git repository with .git
	rm -rf ${S}
	mv ${WORKDIR}/git ${S}
	else
	# create source for bare cloned git repository
	git clone ${WORKDIR}/git ${S}
	rm -rf ${WORKDIR}/git
	fi
	fi
	cd ${S}
	else
	# case: we have no git repository at all.
	# To support low bandwidth options for building the kernel, we'll just
	# convert the tree to a git repo and let the rest of the process work unchanged

	# if ${S} hasn't been set to the proper subdirectory a default of "linux" is
	# used, but we can't initialize that empty directory. So check it and throw a
	# clear error

	cd ${S}
	if [ ! -f "Makefile" ]; then
	bberror "S is not set to the linux source directory. Check "
	bbfatal "the recipe and set S to the proper extracted subdirectory"
	fi
	rm -f .gitignore
	git init
	git add .
	git commit -q -m "baseline commit: creating repo for ${PN}-${PV}"
	git clean -d -f
	fi

	# convert any remote branches to local tracking ones
	for i in `git branch -a --no-color \| grep remotes \| grep -v HEAD`; do
	b=`echo $i \| cut -d' ' -f2 \| sed 's%remotes/origin/%%'`;
	git show-ref --quiet --verify -- "refs/heads/$b"
	if [ $? -ne 0 ]; then
	git branch $b $i > /dev/null
	fi
	done

	# Create a working tree copy of the kernel by checking out a branch
	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"

	# checkout and clobber any unimportant files
	git checkout -f ${machine_branch}
	}
	do_kernel_checkout[dirs] = "${S}"

	addtask kernel_checkout before do_kernel_metadata after do_unpack
	addtask kernel_metadata after do_validate_branches do_unpack before do_patch
	do_kernel_metadata[depends] = "kern-tools-native:do_populate_sysroot"

	do_kernel_configme[dirs] += "${S} ${B}"
	do_kernel_configme() {
	bbnote "kernel configme"
	export KMETA=${KMETA}

	if [ -n "${KCONFIG_MODE}" ]; then
	configmeflags=${KCONFIG_MODE}
	else
	# If a defconfig was passed, use =n as the baseline, which is achieved
	# via --allnoconfig
	if [ -f ${WORKDIR}/defconfig ]; then
	configmeflags="--allnoconfig"
	fi
	fi

	cd ${S}
	PATH=${PATH}:${S}/scripts/util
	configme ${configmeflags} --reconfig --output ${B} ${LINUX_KERNEL_TYPE} ${KMACHINE}
	if [ $? -ne 0 ]; then
	bbfatal_log "Could not configure ${KMACHINE}-${LINUX_KERNEL_TYPE}"
	fi

	echo "# Global settings from linux recipe" >> ${B}/.config
	echo "CONFIG_LOCALVERSION="\"${LINUX_VERSION_EXTENSION}\" >> ${B}/.config
	}

	addtask kernel_configme before do_configure after do_patch

	python do_kernel_configcheck() {
	import re, string, sys

	# if KMETA isn't set globally by a recipe using this routine, we need to
	# set the default to 'meta'. Otherwise, kconf_check is not passed a valid
	# meta-series for processing
	kmeta = d.getVar( "KMETA", True ) or "meta"
	if not os.path.exists(kmeta):
	kmeta = "." + kmeta

	pathprefix = "export PATH=%s:%s; " % (d.getVar('PATH', True), "${S}/scripts/util/")
	cmd = d.expand("cd ${S}; kconf_check -config %s/meta-series ${S} ${B}" % kmeta)
	ret, result = oe.utils.getstatusoutput("%s%s" % (pathprefix, cmd))

	config_check_visibility = int(d.getVar( "KCONF_AUDIT_LEVEL", True ) or 0)
	bsp_check_visibility = int(d.getVar( "KCONF_BSP_AUDIT_LEVEL", True ) or 0)

	# if config check visibility is non-zero, report dropped configuration values
	mismatch_file = "${S}/" + kmeta + "/" + "mismatch.cfg"
	if os.path.exists(mismatch_file):
	if config_check_visibility:
	with open (mismatch_file, "r") as myfile:
	results = myfile.read()
	bb.warn( "[kernel config]: specified values did not make it into the kernel's final configuration:\n\n%s" % results)

	# if config check visibility is level 2 or higher, report non-hardware options
	nonhw_file = "${S}/" + kmeta + "/" + "nonhw_report.cfg"
	if os.path.exists(nonhw_file):
	if config_check_visibility > 1:
	with open (nonhw_file, "r") as myfile:
	results = myfile.read()
	bb.warn( "[kernel config]: BSP specified non-hw configuration:\n\n%s" % results)

	bsp_desc = "${S}/" + kmeta + "/" + "top_tgt"
	if os.path.exists(bsp_desc) and bsp_check_visibility > 1:
	with open (bsp_desc, "r") as myfile:
	bsp_tgt = myfile.read()
	m = re.match("^(.)scratch.obj(.)$", bsp_tgt)
	if not m is None:
	bb.warn( "[kernel]: An auto generated BSP description was used, this normally indicates a misconfiguration.\n" +
	"Check that your machine (%s) has an associated kernel description." % "${MACHINE}" )
	}

	# Ensure that the branches (BSP and meta) are on the locations specified by
	# their SRCREV values. If they are NOT on the right commits, the branches
	# are corrected to the proper commit.
	do_validate_branches() {
	set +e
	cd ${S}

	machine_branch="${@ get_machine_branch(d, "${KBRANCH}" )}"
	machine_srcrev="${SRCREV_machine}"

	# if SRCREV is AUTOREV it shows up as AUTOINC there's nothing to
	# check and we can exit early
	if [ "${machine_srcrev}" = "AUTOINC" ]; then
	bbnote "SRCREV validation is not required for AUTOREV"
	elif [ "${machine_srcrev}" = "" ]; then
	if [ "${SRCREV}" != "AUTOINC" ] && [ "${SRCREV}" != "INVALID" ]; then
	# SRCREV_machine_<MACHINE> was not set. This means that a custom recipe
	# that doesn't use the SRCREV_FORMAT "machine_meta" is being built. In
	# this case, we need to reset to the give SRCREV before heading to patching
	bbnote "custom recipe is being built, forcing SRCREV to ${SRCREV}"
	force_srcrev="${SRCREV}"
	fi
	else
	git cat-file -t ${machine_srcrev} > /dev/null
	if [ $? -ne 0 ]; then
	bberror "${machine_srcrev} is not a valid commit ID."
	bbfatal_log "The kernel source tree may be out of sync"
	fi
	force_srcrev=${machine_srcrev}
	fi

	git checkout -q -f ${machine_branch}
	if [ -n "${force_srcrev}" ]; then
	# see if the branch we are about to patch has been properly reset to the defined
	# SRCREV .. if not, we reset it.
	branch_head=`git rev-parse HEAD`
	if [ "${force_srcrev}" != "${branch_head}" ]; then
	current_branch=`git rev-parse --abbrev-ref HEAD`
	git branch "$current_branch-orig"
	git reset --hard ${force_srcrev}
	fi
	fi
	}

	# Many scripts want to look in arch/$arch/boot for the bootable
	# image. This poses a problem for vmlinux based booting. This
	# task arranges to have vmlinux appear in the normalized directory
	# location.
	do_kernel_link_vmlinux() {
	if [ ! -d "${B}/arch/${ARCH}/boot" ]; then
	mkdir ${B}/arch/${ARCH}/boot
	fi
	cd ${B}/arch/${ARCH}/boot
	ln -sf ../../../vmlinux
	}

	OE_TERMINAL_EXPORTS += "KBUILD_OUTPUT"
	KBUILD_OUTPUT = "${B}"

	python () {
	# If diffconfig is available, ensure it runs after kernel_configme
	if 'do_diffconfig' in d:
	bb.build.addtask('do_diffconfig', None, 'do_kernel_configme', d)
	}