2018/2/20にコミットされたものがQAを経てのリリースとなっています。
“Meltdown”及び“Spectre”への対応として、gcc7.2がgcc7.3に変更となっています。
gcc6,3からgcc6.4に関しましては、今後の対応となります。

注意点ですが、Release Noteで記載されているupdate/Fixは、現時点のFixであり、2018/2/20の段階では
対応が行われていないものもあります。

本リリースの詳細は以下のURLにてご確認ください。
https://lists.yoctoproject.org/pipermail/yocto-announce/2018-March/00013...
---------------
Known Issues
---------------
https://bugzilla.yoctoproject.org/show_bug.cgi?id=12587

Runtime providers were sometimes changing order during builds, resulting in non-deterministic build results.

Example:

DEBUG: providers for lib32-initd-functions are: ['lib32-lsbinitscripts', 'lib32-initscripts']
or
DEBUG: providers for lib32-initd-functions are: ['lib32-initscripts', 'lib32-lsbinitscripts']

This can lead to test failures.

This is fixed with Bitbake rev: 223a0f68530571d2280f526bddbc718fa803a3dc
This change ensures we don't rely on the random order of dictionaries in
memory and act deterministically.

---------------
Security Fixes
---------------
glibc: Security fix CVE-2017-17426
glibc: Security Fix CVE-2017-16997
glibc: Security fix CVE-2017-15671
glibc: Security fix CVE-2017-15670

---------------
Fixes
---------------
glibc: Update to tip of 2.26
glibc: Adapt do_install_append_aarch64() for usrmerge
libtirpc: refresh patches
libtirpc: stop dropping in NIS headers
libunwind: Fix multilib header conflict - libunwind.h
libmpc: fix SRC_URI
siteinfo: add aarch64_illp32 decode
update-rc.d: QA regression.
webkitgtk_2.18.6.bb: Fix configure failure for aarch64 build
eglinfo-fb: Pass -DMESA_EGL_NO_X11_HEADERS to cxxflags
openssl: remove patch from 1.0.2m left behind after update to 1.0.2n
p11-kit: take source code from official git
meta-yocto-bsp: bump to the latest linux stable kernel for the non-x86 BSPs
linux-yocto: update genericx86* SRCREVs for v4.4
linux-yocto: update genericx86* SRCREVs for v4.9
linux-yocto: update genericx86* SRCREVs for v4.12
meta-yocto-bsp: bump to the latest linux stable kernel for the non-x86 BSPs
linux-yocto/4.12: fix qemuarm64 boot failure
kernel-yocto/4.9: update to v4.9.82
linux-yocto/4.12: update to v4.12.20
libc6: improve reproducibility
musl: Disable thumb1 ISA
musl: prevent errors if do_install is run more than once
musl: Update to 1.1.18
musl: Update to latest
gcc-7.3: Drop upstreamed musl cpuinfo patch
packagegroup-core-tools-profile: disable valgrind on armeb
webkitgtk: update to 2.18.6
linux-yocto/4.12: pinctrl backports
package_rpm.bbclass: Fix matching of architecture independent packages
openssl: update to 1.0.2n
openssl-ptest: improve reproducibility
build-appliance-image: Update to rocko head revision
poky.conf: Bump version for 2.4.2 rocko release
documentation: Updated Manual Revision Table for 2.4.2 Release Date
yocto-project-qs: Fixed spelling error in Welcome section
dev-manual: Fixed variable link to DEFAULTTUNE variable
ref-manual: Removed Ubuntu 14.04 from Supported Linux Distribution
documentation: Prepared files for a 2.4.2 point release
ref-manual, yocto-project-qs, poky.ent: Fixed CentOS package
mega-manual: Updated sdk-manual figure used
ref-manual: Updated Note to use bullet form and fixed link to sdk-manual
ref-manual, yocto-project-qs: Fixed targets for sdk-manual links
mega-manual.sed: Fixed string for sdk-manual links
net-tools: change a '=' to '+='
kernel-uboot: support Image kernel type for arm64
libunwind: Fix PACKAGECONFIG option typo
glibc-locale.inc: avoid duplicate packages
tzdata: update to 2018c
tzcode: update to 2018c
grub: Move grub-editenv packaging to grub2.inc
grub-efi: Add loadenv and test as default built-in
grub-efi: Rework GRUB_BUILTIN variable as it is too long
grub-efi: Fix DEPENDS
libarchive: Enable xz and lzo by default
libepoxy: Fix build break for EGL_CAST dependency
image_types_wic.bbclass: Ensure '-c image_wic' works
uninative.bbclass: Fix broken symlink issue
linux-yocto/4.12: update to v4.12.19
linux-yocto/4.9: update to v4.9.78
linux-yocto/4.4: update to v4.4.113
linux-yocto/4.12: iwlwifi and pci id backports
kernel-yocto: make SRC_URI defconfig removal more specific
linux-yocto/4.12: drm & mips fixes
linux-yocto/4.12: coffeeLake-s graphics and audio support
linux-yocto/4.12: CQM and rdt backports
linux-yocto/4.4: update to 4.4.99
linux-yocto/4.9: fix aufs build
linux-yocto/4.9: update to v4.9.71
gcc: Upgrade 7.2 -> 7.3
lz4: remove ptest changes
lz4: fix upstream version check
glibc: fix C++ compile failures related to 'assert'
populate_sdk_ext: Set cleandirs correctly
lib/oe/package_manager/sdk: Ensure do_populate_sdk_ext and do_populate_sdk repos don't conflict
image: Expand PV to avoid AUTOREV parsing failures
webkitgtk: update to 2.18.5 (includes Spectre mitigations; see commit description)
pax-utils: update SRC_URI
linux-firmware: Bump to bf04291 revision
linux-firmware: Split out the QAT firmware
libunwind: Disable documentation explicitly
oeqa/runtime/buildcpio: Use our own mirror for source
binutils: Convert SRC_URI and SRCREV to weak defines
binutils: update to 2.29.1
acpica: fix build with x32
boost: fix build with x32 and musl
runqemu: Add workaround for APIC hang on pre 4.15 kernels on qemux86
glib-2.0: Add python3 modules required by gdbus-codegen
lib/oe/patch: add missing import
bmap-tools: fix RDEPENDS and update SRC_URI
rm_work: remove debugging statements
kernel-fitimage: Fix bad image type replacement for aarch64
image-live.bbclass: add MLPREFIX to core-image-minimal-initramfs
image-live.bbclass: print warn when initramfs is invalid
wic: Fix a path to a psuedo state directory (PSEUDO_LOCALSTATEDIR).
waf.bbclass: explicitly pass bindir and libdir if supported
kernel.bbclass: Fix do_sizecheck behaviour
image_types: btrfs use sparse file creation
rm_work: Handle race with -inital tasks
linux-yocto/4.12: CQM and kmemleak fixes
linux-yocto/4.12: common-pc*: enable X2APIC by default
linux-yocto/4.12: update to v.4.12.18
linux-yocto/4.12: bug fixes and feature backports
linux-yocto/4.x: configuration updates
linux-yocto/4.12: ipv4 stable backport and config changes
linux-yocto/4.12: bug fixes and VRF feature addition
linux-yocto/4.12: update to v4.12.16
systemd: fix segfault when terminating systemd --test
recipetool: create: fix conflict between SRCREV and tag
libxslt: use HTTP instead of FTP in SRC_URI
ovmf: Fix build failure for PARALLEL_MAKE with no space
kernel-yocto: ensure that only a single defconfig is processed
kernel-yocto: Stop the build if defconfig is missing
kernel-yocto: ensure sccs variable is set when using KBUILD_DEFCONFIG
linux-yocto/4.9: update to v4.9.65
linux-yocto/4.12: iwlwifi calltrace fixes and configuration warning cleanups
linux-yocto/4.9: update to v4.9.61
rootfs-postcommands.bbclass: ensure that rootfs gets mounted ro
connman.inc: do not check IMAGE_FEATURES
templates/layer.conf: remove backslash to enable bbappend setting
systemd: allow dots in arguments to template units
package_manager: force dnf to refresh the cache
meta-selftest: fix upstream version checks for devtool test recipes
mtd-utils: fix flash_eraseall installation conflict
wpa-supplicant: add a missing WPA_COMMON_CTRL_IFACE definition
update-alternatives.bbclass: refuse to manage SysV init scripts
Revert "classes: Fix alternatives and rc.d ordering"
initscripts: rrecommend initscripts-functions
lsbinitscripts: don't use update-alternatives
initscripts: don't use update-alternatives
sysklogd: don't use update-alternatives
install*.sh: add short sleep after parted commands
init-install: fix grub-install command
initramfs-module-install: Remove allarch and FILESEXTRAPATHS
initramfs-framework: add install module
initramfs-module-install-efi: update summary
initramfs-module-install-efi: point to original copy and delete new file
wic: support filesystem label for rawcopy
openssl: fix runtime errors with Thumb2 when using binutils 2.29
openssl: Upgrade 1.1.0f -> 1.1.0g
openssl10: fix runtime errors with Thumb2 when using binutils 2.29
openssl10: Upgrade 1.0.2l -> 1.0.2m
python[3]-setuptools: inherit setuptools
local.conf.sample: Weakly set BB_DISKMON_DIRS
documentation: Prepped manual set for a 2.4.1 point release
bitbake: toaster: add 'nobuild' option to Toaster
bitbake: toaster: landing page show cmdline capture
bitbake: toaster: enable custom env support for shell calls
bitbake: toaster: some recipe events do not include packages
bitbake: toaster: update Toaster for Django 1.11
bitbake: toaster: unset BBPATH before starting bbserver for backwards compatibility
populate_sdk_ext: Use prebuilt uninative tarball
makefile: Removed "yocto-environment.png" from tar list of mega-manual
ref-manual: Fixed redundant link for "build system"
ref-manual: Added new terms to Yocto Project Terms section.
dev-manual: Updated bitbake-layers overview section.
ref-manual: 2.4 Migration Revisions
build-appliance: Fix branch name