When emerging sys-kernel/linux-firmware with the "initramfs" USE flag and then configuring my grub config to this: linux /boot/vmlinuz root=UUID=30ffd27c-9d7d-434e-9ed5-6bb46e945050 ro init=/lib/systemd/systemd quiet systemd.show_status=1 echo 'Loading initial ramdisk ...' initrd /boot/amd-uc.img the kernel is unbootable. It aborts with a kernel panic very early on, when it tries to mount the initramfs image: Kernel panic - not syncing: VFS: Unable to mount root fs on unknown block(0,0) This happens both with sys-kernel/gentoo-kernel-bin-5.10.15 as well as with a manually compiled sys-kernel/gentoo-sources (using the same config as gentoo-kernel-bin.)
$ emerge --info sys-kernel/linux-firmware Portage 3.0.14 (python 3.8.7-final-0, default/linux/amd64/17.1/desktop/plasma/systemd, gcc-10.2.0, glibc-2.32-r7, 5.10.15-gentoo x86_64) ================================================================= System Settings ================================================================= System uname: Linux-5.10.15-gentoo-x86_64-AMD_Ryzen_7_3700X_8-Core_Processor-with-glibc2.2.5 KiB Mem: 16384624 total, 13897096 free KiB Swap: 4219712 total, 4219712 free Timestamp of repository gentoo: Thu, 11 Feb 2021 13:00:01 +0000 Head commit of repository gentoo: 20a697ec94dd5f167b50a970bba0bffccbd70775 Timestamp of repository steam-overlay: Sat, 23 Jan 2021 10:41:07 +0000 Head commit of repository steam-overlay: d4fc70b86dcf24462ef302663199c26de4be50cd sh bash 5.1_p4 ld GNU ld (Gentoo 2.35.2 p1) 2.35.2 app-shells/bash: 5.1_p4::gentoo dev-lang/perl: 5.32.0-r1::gentoo dev-lang/python: 3.8.7-r1::gentoo dev-util/cmake: 3.19.4::gentoo sys-apps/baselayout: 2.7-r1::gentoo sys-apps/sandbox: 2.20::gentoo sys-devel/autoconf: 2.13-r1::gentoo, 2.69-r5::gentoo sys-devel/automake: 1.16.3-r1::gentoo sys-devel/binutils: 2.35.2::gentoo sys-devel/gcc: 10.2.0-r5::gentoo sys-devel/gcc-config: 2.3.3::gentoo sys-devel/libtool: 2.4.6-r6::gentoo sys-devel/make: 4.3::gentoo sys-kernel/linux-headers: 5.10::gentoo (virtual/os-headers) sys-libs/glibc: 2.32-r7::gentoo Repositories: gentoo location: /var/db/repos/gentoo sync-type: rsync sync-uri: rsync://rsync.gentoo.org/gentoo-portage priority: -1000 sync-rsync-verify-jobs: 1 sync-rsync-extra-opts: sync-rsync-verify-max-age: 24 sync-rsync-verify-metamanifest: yes local location: /usr/local/portage masters: gentoo steam-overlay location: /var/db/repos/steam-overlay sync-type: git sync-uri: https://github.com/gentoo-mirror/steam-overlay.git masters: gentoo ACCEPT_KEYWORDS="amd64 ~amd64" ACCEPT_LICENSE="*" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-O2 -pipe -mtune=native -march=native -ftree-vectorize" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/config /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/vmware-installer" CXXFLAGS="-O2 -pipe -mtune=native -march=native -ftree-vectorize" DISTDIR="/var/cache/distfiles" EMERGE_DEFAULT_OPTS="--backtrack=200 --quiet-build=y --with-bdeps=y" ENV_UNSET="CARGO_HOME DBUS_SESSION_BUS_ADDRESS DISPLAY GOBIN GOPATH PERL5LIB PERL5OPT PERLPREFIX PERL_CORE PERL_MB_OPT PERL_MM_OPT XAUTHORITY XDG_CACHE_HOME XDG_CONFIG_HOME XDG_DATA_HOME XDG_RUNTIME_DIR" FCFLAGS="-O2 -pipe -mtune=native -march=native -ftree-vectorize" FEATURES="assume-digests binpkg-docompress binpkg-dostrip binpkg-logs cgroup config-protect-if-modified distlocks ebuild-locks fixlafiles ipc-sandbox merge-sync multilib-strict network-sandbox news parallel-fetch pid-sandbox preserve-libs protect-owned qa-unresolved-soname-deps sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr" FFLAGS="-O2 -pipe -mtune=native -march=native -ftree-vectorize" GENTOO_MIRRORS="http://ftp-stud.hs-esslingen.de/pub/Mirrors/gentoo/ http://ftp.ntua.gr/pub/linux/gentoo/" LANG="en-US.UTF8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" LINGUAS="en_US en" MAKEOPTS="-j16" PKGDIR="/var/cache/binpkgs" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git" PORTAGE_TMPDIR="/var/tmp" USE="X a52 aac acl acpi activities amd64 berkdb branding bzip2 cairo cdr cli crypt dbus declarative dist-kernel dri dts dvdr emboss encode exif flac fortran gdbm gif gpm grub gtk gui iconv icu ipv6 jpeg kde kipi kwallet lcms libglvnd libnotify libtirpc lto mad mng mp3 mp4 mpeg multilib ncurses networkmanager nptl nvidia offensive ogg opengl openmp pam pango pcre pdf pgo phonon plasma png policykit ppds pulseaudio qml qt5 readline sdl seccomp spell split-usr ssl startup-notification svg systemd tcpd tiff truetype udev udisks unicode upower usb vorbis vulkan widgets wxwidgets x264 xattr xcb xml xv xvid zlib" ABI_X86="64" ADA_TARGET="gnat_2018" ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0 intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="karbon sheets words" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx avx2 f16c fma3 mmx mmxext pclmul popcnt rdrand sha sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock greis isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="libinput" KERNEL="linux" L10N="en-US en" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LLVM_TARGETS="WebAssembly" LUA_SINGLE_TARGET="lua5-1" LUA_TARGETS="lua5-1" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php7-3 php7-4" POSTGRES_TARGETS="postgres10 postgres11" PYTHON_SINGLE_TARGET="python3_8" PYTHON_TARGETS="python3_8" RUBY_TARGETS="ruby26" USERLAND="GNU" VIDEO_CARDS="nvidia" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: CC, CPPFLAGS, CTARGET, CXX, INSTALL_MASK, LC_ALL, PORTAGE_BINHOST, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS ================================================================= Package Settings ================================================================= sys-kernel/linux-firmware-20210208::gentoo was built with the following: USE="initramfs redistributable -savedconfig (-unknown-license)" ABI_X86="(64)"
sys-kernel/linux-firmware does not provide a complete initramfs. It provides an early microcode initramfs with just the microcode image. To boot using a UUID for root, you must also configure a full-featured initramfs. This may be generated by something like dracut or genkernel.
Alternatively, you could pass a block device name or partition UUID to the kernel instead of a UUID. The kernel is able to interpret these without the use of an initramfs. For example: root=/dev/sda1 root=PARTUUID=b5f48230-bc75-4e71-8839-f948ee324e2c
Ah, thank you! That indeed works.
