/dev/root doesn't exists m_melnikau-vaio ~ # mount rootfs on / type rootfs (rw) /dev/root on / type btrfs (rw,relatime) Reproducible: Always Steps to Reproduce: 1. emerge systemd 2. unmask grub2 3. run grub2-mkconfig Actual Results: /sbin/grub2-probe: error: cannot find a device for / (is /dev mounted?). Expected Results: some grub2 config ~ # stat /dev/root stat: cannot stat `/dev/root': No such file or directory ~ # cat /proc/self/mounts rootfs / rootfs rw 0 0 /dev/root / btrfs rw,relatime 0 0 devtmpfs /dev devtmpfs rw,relatime,size=1949488k,nr_inodes=487372,mode=755 0 0 proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0 sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0 tmpfs /dev/shm tmpfs rw,nosuid,nodev,relatime 0 0 devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0 tmpfs /run tmpfs rw,nosuid,nodev,relatime,mode=755 0 0 tmpfs /sys/fs/cgroup tmpfs rw,nosuid,nodev,noexec,relatime,mode=755 0 0 cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd 0 0 cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0 cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpuacct,cpu 0 0 cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0 cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0 cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0 cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0 cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0 systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=20,pgrp=1,timeout=300,minproto=5,maxproto=5,direct 0 0 tmpfs /var/run tmpfs rw,nosuid,nodev,relatime,mode=755 0 0 mqueue /dev/mqueue mqueue rw,relatime 0 0 fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0 configfs /sys/kernel/config configfs rw,relatime 0 0 tmpfs /media tmpfs rw,nosuid,nodev,noexec,relatime,mode=755 0 0 /dev/sda5 /boot ext4 rw,relatime,user_xattr,acl,barrier=1,data=ordered 0 0 /dev/sda9 /home ext4 rw,relatime,user_xattr,acl,barrier=1,data=ordered 0 0 ~ # cat /etc/fstab <dump/pass> UUID=339f07bd-78b5-48df-9c1a-0fef28be93f9 /boot ext4 defaults 0 2 UUID=41ab6314-cbef-4f03-80c7-0996e7ed4601 /home ext4 defaults 0 2 UUID=43b6466a-02c1-468d-98ad-2ab36c92786b none swap sw 0 0 UUID=5210029c-cfef-40b8-b193-67457dc7cede / btrfs defaults 0 0 ~ # cat /boot/grub/grub.cfg menuentry 'Gentoo 3.1.0 systemd' --class gentoo --class gnu-linux --class gnu --class os { insmod part_msdos linux /boot/kernel-genkernel-x86_64-3.1.0-gentoo-r1 root=/dev/sda8 init=/bin/systemd } m_melnikau-vaio ~ # emerge --info Portage 2.1.10.34 (default/linux/amd64/10.0/desktop/kde, gcc-4.6.1, glibc-2.13-r4, 3.1.0-gentoo-r1 x86_64) ================================================================= System uname: Linux-3.1.0-gentoo-r1-x86_64-Intel-R-_Core-TM-_i5_CPU_M_430_@_2.27GHz-with-gentoo-2.1 Timestamp of tree: Sat, 12 Nov 2011 11:00:01 +0000 distcc 3.1 x86_64-pc-linux-gnu [disabled] app-shells/bash: 4.2_p10 dev-java/java-config: 2.1.11-r3 dev-lang/python: 2.6.7-r2, 2.7.2-r3, 3.1.4-r3, 3.2.2 dev-util/cmake: 2.8.6-r3 dev-util/pkgconfig: 0.26 sys-apps/baselayout: 2.1 sys-apps/openrc: 0.9.4 sys-apps/sandbox: 2.5 sys-devel/autoconf: 2.13, 2.68 sys-devel/automake: 1.9.6-r3, 1.10.3, 1.11.1-r1 sys-devel/binutils: 2.21.1-r1 sys-devel/gcc: 4.4.4-r2, 4.5.3-r1, 4.6.1-r1 sys-devel/gcc-config: 1.5-r2 sys-devel/libtool: 2.4-r4 sys-devel/make: 3.82-r3 sys-kernel/linux-headers: 2.6.39 (virtual/os-headers) sys-libs/glibc: 2.13-r4 Repositories: gentoo sunrise systemd qting-edge local ACCEPT_KEYWORDS="amd64 ~amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-march=corei7 -Os -pipe" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/config /usr/share/gnupg/qualified.txt /usr/share/openvpn/easy-rsa /usr/share/themes/oxygen-gtk/gtk-2.0" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-march=corei7 -Os -pipe" DISTDIR="/usr/portage/distfiles" FEATURES="assume-digests binpkg-logs distlocks ebuild-locks fixlafiles metadata-transfer news parallel-fetch protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch" FFLAGS="" GENTOO_MIRRORS="http://distfiles.gentoo.org" LANG="en_US.UTF-8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" LINGUAS="en ru" MAKEOPTS="-j2" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages" PORTAGE_TMPDIR="/var/tmp" PORTDIR="/usr/portage" PORTDIR_OVERLAY="/var/lib/layman/sunrise /var/lib/layman/systemd /var/lib/layman/qting-edge /usr/local/portage" SYNC="rsync://rsync.gentoo.org/gentoo-portage" USE="X a52 aac aalib acpi alsa amd64 avahi berkdb bluetooth branding bzip2 cairo cdda cdr cli consolekit cracklib crypt cups curl cxx dbus declarative djvu dri dts dv dvd dvdr emboss encode exif fam ffmpeg firefox flac ftp gdbm gdu gif gnome-keyring gnutls gpm gps gsm gstreamer iconv icu imagemagick ios ipod ipv6 jingle jpeg jpeg2k kde kipi lame latex lcms ldap libcaca libnotify lm_sensors lzma lzo mad mmx mng modules mp3 mp4 mpeg mplayer mtp mudflap multilib musicbrainz ncurses netboot networkmanager nls nptl nptlonly ogg openal opengl openmp oscar pam pango pcre pdf phonon plasma png policykit portaudio postgres ppds pppd pulseaudio qt3support qt4 rdesktop readline ruby samba sdl semantic-desktop session smp speex spell sqlite sqlite3 sse sse2 ssl startup-notification subversion svg sysfs taglib tcpd theora tiff truetype udev unicode usb v4l v4l2 vaapi vim-syntax vnc vorbis wifi x264 xcb xcomposite xine xinerama xml xorg xscreensaver xulrunner xv xvid zeroconf zlib zsh-completion" 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" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="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="kexi words flow plan stage tables krita karbon braindump" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ubx" INPUT_DEVICES="keyboard mouse evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="en ru" PHP_TARGETS="php5-3" QEMU_SOFTMMU_TARGETS="x86_64 i386" QEMU_USER_TARGETS="x86_64 i386" RUBY_TARGETS="ruby18" USERLAND="GNU" VIDEO_CARDS="radeon dummy fbdev" 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: CPPFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS
e.g. system boots and runs successfully, problem is that /dev/root missing (how in this case fs was mounted?)
<kay> mgorny: /dev/root was distro specific, we don't do that anymore, and recommend not having it <kay> mgorny: it will break with stuff like btrfs, and tools should learn to live without it So, using it is a bug in grub. If base-system really insists on that, I guess we can add some fallback but fixing grub seems like a better idea to me.
i don't think /dev/root was distro specific. the kernel provides that info. simply look in /proc/mounts.
(In reply to comment #3) > i don't think /dev/root was distro specific. the kernel provides that info. > simply look in /proc/mounts. <kay> mgorny: no, it's a dead text string in case initramfs is not used, it is no info <kay> mgorny: the kernel does an mknod() in an invisible namespace to mount / <kay> mgorny: it's not an info that is intentional
(In reply to comment #4) this link has never been managed by openrc/baselayout that i can see. in Gentoo, udev is creating it. sounds like the systemd unit that you've made for udev isn't a complete replacement for the Gentoo init.d script. $ grep root /etc/init.d/udev root_link() /lib/udev/write_root_link_rule root_link
(In reply to comment #5) > (In reply to comment #4) > > this link has never been managed by openrc/baselayout that i can see. in > Gentoo, udev is creating it. sounds like the systemd unit that you've made for > udev isn't a complete replacement for the Gentoo init.d script. > > $ grep root /etc/init.d/udev > root_link() > /lib/udev/write_root_link_rule > root_link That's why I said I can add it as backwards compat but kay here (who is udev dev btw) says it is a bad idea after all. I wouldn't be suprised if that binary disappeared sometime soon :P.
(In reply to comment #6) that isn't a binary. it's a script the udev ebuild installs. as for grub, i think that's upstream code checking /dev/root, so the better place to report this would be the grub bugzilla.
(In reply to comment #7) > as for grub, i think that's upstream code checking /dev/root, so the better > place to report this would be the grub bugzilla. That's why I reassigned the bug to someone who's supposed to have an account there :P.
but you didn't re-assign it to someone who agrees/cares with your request :P
The write_root_link_rule is something that is added to udev by our ebuild, so /dev/root is in fact distro specific. If upstreams are using it, they shouldn't be.
Udev-171-r4 fixes the script to write the rule correctly on systemd systems, so this bug could be closed. However, a bug should be opened against grub upstream to get this fixed properly if grub is using /dev/root.
systemd-37 requires at least udev-172, udev-175 doesn't have this fix. Could you add fix to udev-175 too?
Did you check udev-175-r1? the fix should be there as well.
I don't see shell-compat-KV.sh related fix in udev-175-r1, and still # grub2-mkconfig /sbin/grub2-probe: error: cannot find a device for / (is /dev mounted?).
(In reply to comment #14) > I don't see shell-compat-KV.sh related fix in udev-175-r1, and still > # grub2-mkconfig > /sbin/grub2-probe: error: cannot find a device for / (is /dev mounted?). The shell-compat-KV.sh fix is not the one you want for this bug. Look at /lib/udev/write_root_link_rule. The fix is in there. If you haven't rebooted, you may need to run rc-service udev restart.
It think this is a manifestation of bug 381761. Basically, /dev/root appears in /proc/mounts if you have a btrfs root filesystem and no initramfs.
For more info on what might be causing this, you might want to look at bug #381761. Is that your issue? do you have a btrfs root filesystem?
Yes, I use btrfs on / and no initrd, so, now this bug looks for me as duplicate of bug 381761
(In reply to comment #18) > Yes, I use btrfs on / and no initrd, so, now this bug looks for me as duplicate > of bug 381761 I have the same problem, after a stage4 migration to a larger hard disk. btrfs on / and no initrd. # grub2-probe / grub2-probe: error: cannot find a device for / (is /dev mounted?). The problem was reported in gentoo forum: http://forums.gentoo.org/viewtopic-p-6890676.html For me 'udevadm info --export --export-prefix="ROOT_" --device-id-of->file=/' gives ROOT_MAJOR=0 also, and so write_root_link_rule exits without writing the rule. This is for udev-171-r5 and grub-1.99-r2.
i'm not sure how you can say /dev/root is distro specific when it's the kernel that uses this naming convention $ cd /usr/src/linux $ grep /dev/root init/*.c init/do_mounts.c: fd = sys_open("/dev/root", O_RDWR | O_NDELAY, 0); init/do_mounts.c: create_dev("/dev/root", ROOT_DEV); init/do_mounts.c: mount_block_root("/dev/root", root_mountflags); init/do_mounts_initrd.c: create_dev("/dev/root.old", Root_RAM0); init/do_mounts_initrd.c: mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY); init/do_mounts_initrd.c: int fd = sys_open("/dev/root.old", O_RDWR, 0); init/do_mounts_rd.c: create_dev("/dev/root", ROOT_DEV); init/do_mounts_rd.c: return rd_load_image("/dev/root"); $ grep /dev/root /proc/mounts /dev/root / ext4 rw,noatime,data=ordered 0 0
*** Bug 430426 has been marked as a duplicate of this bug. ***
*** Bug 427818 has been marked as a duplicate of this bug. ***
*** Bug 438028 has been marked as a duplicate of this bug. ***
(In reply to comment #20) > i'm not sure how you can say /dev/root is distro specific when it's the > kernel that uses this naming convention > Just ask Linus about that, I'm sure he'll deal with Kay appropriately.
(In reply to comment #24) > (In reply to comment #20) > > i'm not sure how you can say /dev/root is distro specific when it's the > > kernel that uses this naming convention > > > > Just ask Linus about that, I'm sure he'll deal with Kay appropriately. I don't see where the kernel is using this naming convention. it isn't on my box at all, and it doesn't appear when I run "grep /dev/root /proc/mounts". "/dev/root" was created by write_root_link_rule, which was a gentoo specific addon to udev.
On my system I have /dev/root in /proc/mounts, but not in /etc/fstab. I use ext4 as a root fs, udev-194 and openrc-0.9.9.3. My kernel is configured to support and mount devtmpfs, that is where /dev/root is created in the first place: CONFIG_DEVTMPFS=y CONFIG_DEVTMPFS_MOUNT=y just to be remounted and removed later by all-the-clever udev.
(In reply to comment #26) > On my system I have /dev/root in /proc/mounts, but not in /etc/fstab. I use > ext4 as a root fs, udev-194 and openrc-0.9.9.3. And which version of udev-init-scripts? > My kernel is configured to support and mount devtmpfs, that is where > /dev/root is created in the first place: > CONFIG_DEVTMPFS=y > CONFIG_DEVTMPFS_MOUNT=y > just to be remounted and removed later by all-the-clever udev. No. udev-init-scripts does not attempt to remount /dev if you have config_devtmpfs_mount=y. To see that, look in /etc/init.d/udev-mount.
I have sent an email to lkml to ask for sure whether the kernel creates this symlink.
(In reply to comment #27) > (In reply to comment #26) > > On my system I have /dev/root in /proc/mounts, but not in /etc/fstab. I use > > ext4 as a root fs, udev-194 and openrc-0.9.9.3. > > And which version of udev-init-scripts? =sys-fs/udev-init-scripts-16 > > My kernel is configured to support and mount devtmpfs, that is where > > /dev/root is created in the first place: > > CONFIG_DEVTMPFS=y > > CONFIG_DEVTMPFS_MOUNT=y > > just to be remounted and removed later by all-the-clever udev. > > No. udev-init-scripts does not attempt to remount /dev if you have > config_devtmpfs_mount=y. To see that, look in /etc/init.d/udev-mount. Than I have no idea what removes /dev/root. According to /proc/mounts it was definitely there during mount process.
Here is the thread I started on lkml: https://lkml.org/lkml/2012/10/12/483
(In reply to comment #29) > Than I have no idea what removes /dev/root. According to /proc/mounts it was > definitely there during mount process. Are you using an initramfs? If you are not, comment #4 above applies. In other words, /dev/root appearing in /proc/mounts is a left-over from the hidden device that the kernel uses to mount the rootfs.
Another thing to consider is /usr/src/linux/Documentation/devices.txt. See the section on "Locally defined links". Note that all of these links are *optional*, so if software is relying on them, this is a bug in the software.
(In reply to comment #31) > (In reply to comment #29) > > Than I have no idea what removes /dev/root. According to /proc/mounts it was > > definitely there during mount process. > > Are you using an initramfs? If you are not, comment #4 above applies. In > other words, /dev/root appearing in /proc/mounts is a left-over from the > hidden device that the kernel uses to mount the rootfs. No, I don't use initramfs, so this is my case. (In reply to comment #32) > Another thing to consider is /usr/src/linux/Documentation/devices.txt. See > the section on "Locally defined links". > > Note that all of these links are *optional*, so if software is relying on > them, this is a bug in the software. In my case quota doesn't depend on /dev/root, but depends on /proc/mounts which contain non-existent /dev/root, this confuses quota tools, because they can't access mounted device mentioned in /proc/mounts! So either symlink should exist, or /dev/root should not be mentioned in /proc/mounts.
(In reply to comment #33) > So either symlink should exist, or /dev/root should not be mentioned in > /proc/mounts. Ideally, /dev/root should not be mentioned in /proc/mounts. I wrote a script that walks through /proc/mounts and ignores the line mentioning "/dev/root" as the device name. There is also a line mentioning "rootfs" as the device name which needs to be ignored. If you ignore both of those lines, you can still find the root file system in /proc/mounts. I am going to re-open the quotatools bug, because I think the best fix is for quotatools to ignore /dev/root.
(In reply to comment #34) > (In reply to comment #33) > > So either symlink should exist, or /dev/root should not be mentioned in > > /proc/mounts. > > Ideally, /dev/root should not be mentioned in /proc/mounts. Well I suggest you hack up a kernel patch for that then since the kernel uses /dev/root a whole lot.
(In reply to comment #35) > Well I suggest you hack up a kernel patch for that then since the kernel > uses /dev/root a whole lot. You mean like [1] or [2]? [1] https://bugs.gentoo.org/175243#C11 [2] https://bugs.gentoo.org/175243#C12 You probably know these patches better than I would, so would you please update them and see about getting them into the kernel? Thanks, William
To clarify something, I did not mean any sarcasm or nasty tone at all by that last comment. I am just asking you to confirm that's what you meant, and, since you know the patches best, if you would follow up with them. Thanks, William
I spoke with Cardoe on irc, and we both agreed that this is really a kernel issue. I am closing this bug as invalid for that reason and moving everything to #438380. If you are following this bug and want to continue following the work on it, add yourself to the cc list for that bug.
/dev/root is created again by >=sys-fs/udev-init-scripts-25. It's temporary until everything has been ported away from it: grub:0, quota, nilfs-utils, ... So resolution INVALID doesn't really match anymore, changing to FIXED ->
