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authorJuro Bystricky <juro.bystricky@intel.com>2017-08-09 10:48:32 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2017-08-16 00:03:15 +0100
commit55e9485735ae8393b410f30973c785236dc402d2 (patch)
tree9d87c88f5d25599c3cb9a06312cb3c74ed6c92d2 /meta/classes/kernel.bbclass
parentf3da1613c4d19f599ecea34fc9ea7b9935a8a26a (diff)
downloadpoky-55e9485735ae8393b410f30973c785236dc402d2.tar.gz
kernel.bbclass: improve reproducibility
Several tweaks to improve reproducibility: 1. If BUILD_REPRODUCIBLE_BINARIES == 1, set KBUILD_BUILD_TIMESTAMP to a reproducible value. This is either a non-zero SOURCE_DATE_EPOCH, or the value obtained from top entry of GIT repo, or (if there is no GIT repo) fallback to REPRODUCIBLE_TIMESTAMP_ROOTFS as the last resort. Also export KCONFIG_NOTIMESTAMP=1. 2. When compressing vmlinux.gz, use gzip "-n" option 3. Kernel and kernel modules contain hard coded paths referencing the host build system. This is usually because the source code contains __FILE__ at some place. This prevents binary reproducibility. However, some compilers allow remapping of the __FILE__ value. If we detect the compiler is capable of doing this, we replace the source path $(S) part of __FILE__ by a string "/kernel-source". For example: ​/data/master/build/tmp/work-shared/qemux86/kernel-source/drivers/media/v4l2-core/videobuf2-core.​c will be replaced by a reproducible value: /kernel-source/drivers/media/v4l2-core/videobuf2-core.c. (From OE-Core rev: 012a70da7ae0617740cd0cf807d01c3cd912c823) Signed-off-by: Juro Bystricky <juro.bystricky@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'meta/classes/kernel.bbclass')
-rw-r--r--meta/classes/kernel.bbclass39
1 files changed, 36 insertions, 3 deletions
diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
index ce2cab65ae..2a765547ac 100644
--- a/meta/classes/kernel.bbclass
+++ b/meta/classes/kernel.bbclass
@@ -255,8 +255,39 @@ python do_devshell_prepend () {
255 255
256addtask bundle_initramfs after do_install before do_deploy 256addtask bundle_initramfs after do_install before do_deploy
257 257
258get_cc_option () {
259 # Check if KERNEL_CC supports the option "file-prefix-map".
260 # This option allows us to build images with __FILE__ values that do not
261 # contain the host build path.
262 cc_option_supported=`${KERNEL_CC} -Q --help=joined | grep ffile-prefix-map`
263 cc_extra=""
264 if [ $cc_option_supported = "-ffile-prefix-map=<old=new>" ]; then
265 cc_extra=-ffile-prefix-map=${S}=/kernel-source/
266 fi
267 echo $cc_extra
268}
269
258kernel_do_compile() { 270kernel_do_compile() {
259 unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE 271 unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE
272 if [ "$BUILD_REPRODUCIBLE_BINARIES" = "1" ]; then
273 # kernel sources do not use do_unpack, so SOURCE_DATE_EPOCH may not
274 # be set....
275 if [ "$SOURCE_DATE_EPOCH" = "0" ]; then
276 olddir=`pwd`
277 cd ${S}
278 SOURCE_DATE_EPOCH=`git log -1 --pretty=%ct`
279 # git repo not guaranteed, so fall back to REPRODUCIBLE_TIMESTAMP_ROOTFS
280 if [ $? -ne 0 ]; then
281 SOURCE_DATE_EPOCH=${REPRODUCIBLE_TIMESTAMP_ROOTFS}
282 fi
283 cd $olddir
284 fi
285
286 ts=`LC_ALL=C date -d @$SOURCE_DATE_EPOCH`
287 export KBUILD_BUILD_TIMESTAMP="$ts"
288 export KCONFIG_NOTIMESTAMP=1
289 bbnote "KBUILD_BUILD_TIMESTAMP: $ts"
290 fi
260 # The $use_alternate_initrd is only set from 291 # The $use_alternate_initrd is only set from
261 # do_bundle_initramfs() This variable is specifically for the 292 # do_bundle_initramfs() This variable is specifically for the
262 # case where we are making a second pass at the kernel 293 # case where we are making a second pass at the kernel
@@ -270,20 +301,22 @@ kernel_do_compile() {
270 copy_initramfs 301 copy_initramfs
271 use_alternate_initrd=CONFIG_INITRAMFS_SOURCE=${B}/usr/${INITRAMFS_IMAGE_NAME}.cpio 302 use_alternate_initrd=CONFIG_INITRAMFS_SOURCE=${B}/usr/${INITRAMFS_IMAGE_NAME}.cpio
272 fi 303 fi
304 cc_extra=$(get_cc_option)
273 for typeformake in ${KERNEL_IMAGETYPE_FOR_MAKE} ; do 305 for typeformake in ${KERNEL_IMAGETYPE_FOR_MAKE} ; do
274 oe_runmake ${typeformake} CC="${KERNEL_CC}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS} $use_alternate_initrd 306 oe_runmake ${typeformake} CC="${KERNEL_CC} $cc_extra " LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS} $use_alternate_initrd
275 done 307 done
276 # vmlinux.gz is not built by kernel 308 # vmlinux.gz is not built by kernel
277 if (echo "${KERNEL_IMAGETYPES}" | grep -wq "vmlinux\.gz"); then 309 if (echo "${KERNEL_IMAGETYPES}" | grep -wq "vmlinux\.gz"); then
278 mkdir -p "${KERNEL_OUTPUT_DIR}" 310 mkdir -p "${KERNEL_OUTPUT_DIR}"
279 gzip -9c < ${B}/vmlinux > "${KERNEL_OUTPUT_DIR}/vmlinux.gz" 311 gzip -9cn < ${B}/vmlinux > "${KERNEL_OUTPUT_DIR}/vmlinux.gz"
280 fi 312 fi
281} 313}
282 314
283do_compile_kernelmodules() { 315do_compile_kernelmodules() {
284 unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE 316 unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS MACHINE
285 if (grep -q -i -e '^CONFIG_MODULES=y$' ${B}/.config); then 317 if (grep -q -i -e '^CONFIG_MODULES=y$' ${B}/.config); then
286 oe_runmake -C ${B} ${PARALLEL_MAKE} modules CC="${KERNEL_CC}" LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS} 318 cc_extra=$(get_cc_option)
319 oe_runmake -C ${B} ${PARALLEL_MAKE} modules CC="${KERNEL_CC} $cc_extra " LD="${KERNEL_LD}" ${KERNEL_EXTRA_ARGS}
287 320
288 # Module.symvers gets updated during the 321 # Module.symvers gets updated during the
289 # building of the kernel modules. We need to 322 # building of the kernel modules. We need to