| View previous topic :: View next topic |
| Author |
Message |
HotBBQ
Apprentice
Joined: 03 Mar 2004
Posts: 275
Location: West Melbourne, FL
|
 Posted: Thu Mar 12, 2009 1:39 pm Post subject: Questions about /dev/root and rootfs |
 |
|
I just did a fresh install of ~amd64 and I have some questions about rootfs and /dev/root. Here is the output of mount and my fstab.
| Code: |
rootfs on / type rootfs (rw)
/dev/root on / type ext4 (rw,noatime,barrier=1,data=ordered)
proc on /proc type proc (rw,nosuid,nodev,noexec)
rc-svcdir on /lib64/rc/init.d type tmpfs (rw,nosuid,nodev,noexec,size=1024k,mode=755)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec)
udev on /dev type tmpfs (rw,nosuid,size=10240k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,gid=5,mode=620)
shm on /dev/shm type tmpfs (rw,nosuid,nodev,noexec)
/dev/sdb3 on /home type ext4 (rw,noatime)
/dev/sda4 on /net type ext4 (rw,noatime)
usbfs on /proc/bus/usb type usbfs (rw,noexec,nosuid,devmode=0664,devgid=85)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
gvfs-fuse-daemon on /home/bowerad1/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=bowerad1)
|
| Code: |
/dev/sdb1 /boot ext2 noauto,noatime 1 2
/dev/sdb2 none swap sw 0 0
/dev/sdb3 /home ext4 noatime 0 2
/dev/sdb5 / ext4 noatime 0 1
/dev/sda4 /net ext4 noatime 0 2
shm /dev/shm tmpfs nodev,nosuid,noexec 0 0
|
I was curious as to why mount doesn't seem to think /dev/sdb5 is mounted on / and instead lists two separate entries mounted on root (rootfs and /dev/root). I suppose it's working fine as is, except I notice that gparted can't find the mount point for /dev/sdb5. I thought it might be an ext4 issue, but my other ext4 partitions can be seen just fine.
_________________
"If tyranny and oppression come to this land, it will be in the guise of fighting a foreign enemy." -- James Madison |
|
| Back to top |
|
 |
HotBBQ
Apprentice
Joined: 03 Mar 2004
Posts: 275
Location: West Melbourne, FL
|
| Posted: Fri Mar 13, 2009 5:20 pm Post subject: |
|
|
Bump.
_________________
"If tyranny and oppression come to this land, it will be in the guise of fighting a foreign enemy." -- James Madison |
|
| Back to top |
|
|
hensan
l33t
Joined: 26 Jun 2003
Posts: 868
Location: Sweden
|
| Posted: Mon Mar 30, 2009 5:28 pm Post subject: |
|
|
| I noticed this too. Anyone know why it looks like that? |
|
| Back to top |
|
|
BarryK
n00b
Joined: 14 Jul 2009
Posts: 1
|
| Posted: Tue Jul 14, 2009 2:06 am Post subject: |
|
|
I had a similar problem and while searching with google I came across this thread.
I'm a developer for Puppy Linux, and I have worked out a solution for our particular problem.
So, as no one else has responded to the query from you guys, here is my blog post with solution. I don't know if you will find it useful for your situation.
My blog post:
http://puppylinux.com/blog/?viewDetailed=00887
Regards,
Barry Kauler
_________________
http://puppylinux.com |
|
| Back to top |
|
|
legogogo
n00b
Joined: 08 May 2010
Posts: 2
|
| Posted: Sat May 08, 2010 6:36 pm Post subject: |
|
|
My /etc/init.d/mtab:
| Code: | #!/sbin/runscript
# Copyright (c) 2007-2008 Roy Marples <roy@marples.name>
# All rights reserved. Released under the 2-clause BSD license.
description="Update /etc/mtab to match what the kernel knows about"
depend()
{
need root
keyword -prefix
}
start()
{
# /etc/mtab could be a symlink to /proc/mounts
if [ ! -w /etc/mtab -a -L /etc/mtab ]; then
eeinfo "Skipping mtab update (non writeable symlink)"
return 0
fi
ebegin "Updating /etc/mtab"
if ! echo 2>/dev/null >/etc/mtab; then
ewend 1 "/etc/mtab is not updateable"
return 0
fi
# With / as tmpfs we cannot umount -at tmpfs in localmount as that
# makes / readonly and dismounts all tmpfs even if in use which is
# not good. Luckily, umount uses /etc/mtab instead of /proc/mounts
# which allows this hack to work.
RETSTUFF="`grep -v "^rootfs" /proc/mounts`"
ROOTPARTITION="`rdev | grep ' /$' | cut -f 1 -d ' ' | grep -E '/dev/sd|/dev/hd|/dev/mmc'`"
nPATTERN="s%^/dev/root %${ROOTPARTITION} %"
[ "$ROOTPARTITION" ] && RETSTUFF="`echo "$RETSTUFF" | sed -e "$nPATTERN"`"
echo "$RETSTUFF" > /etc/mtab
# Remove stale backups
rm -f /etc/mtab~ /etc/mtab~~
eend 0
} |
|
|
| Back to top |
|
|
peppev
n00b
Joined: 10 Aug 2009
Posts: 26
Location: Italy
|
| Posted: Sat Mar 12, 2011 10:42 am Post subject: |
|
|
Get the same problem after updating my test gentoo box.
Another possible solution, I think, using "readlink" instead
of "rdev", not anymore available in util-linux.
My /etc/init.d/mtab:
| Code: |
#!/sbin/runscript
# Copyright (c) 2007-2008 Roy Marples <roy@marples.name>
# All rights reserved. Released under the 2-clause BSD license.
description="Update /etc/mtab to match what the kernel knows about"
depend()
{
need root
keyword -prefix
}
start()
{
# look in an easy way to where root is mounted from
ROOTFS=$(readlink -f /dev/root)
# /etc/mtab could be a symlink to /proc/mounts
if [ ! -w /etc/mtab -a -L /etc/mtab ]; then
eeinfo "Skipping mtab update (non writeable symlink)"
return 0
fi
ebegin "Updating /etc/mtab"
if ! echo 2>/dev/null >/etc/mtab; then
ewend 1 "/etc/mtab is not updateable"
return 0
fi
# With / as tmpfs we cannot umount -at tmpfs in localmount as that
# makes / readonly and dismounts all tmpfs even if in use which is
# not good. Luckily, umount uses /etc/mtab instead of /proc/mounts
# which allows this hack to work.
grep -v "^[^ ]* / tmpfs " /proc/mounts |
awk '$1 != "rootfs" {print}' | sed 's%/dev/root%'${ROOTFS}'%' > /etc/mtab
# Remove stale backups
rm -f /etc/mtab~ /etc/mtab~~
eend 0
}
|
|
|
| Back to top |
|
|
cach0rr0
Bodhisattva
Joined: 13 Nov 2008
Posts: 4123
Location: Houston, Republic of Texas
|
| Posted: Sat Mar 12, 2011 1:17 pm Post subject: |
|
|
from the kernel documentation:
/usr/src/linux/Documentation/filesystems/ramfs-rootfs-initramfs.txt
| Code: |
What is rootfs?
---------------
Rootfs is a special instance of ramfs (or tmpfs, if that's enabled), which is
always present in 2.6 systems. You can't unmount rootfs for approximately the
same reason you can't kill the init process; rather than having special code
to check for and handle an empty list, it's smaller and simpler for the kernel
to just make sure certain lists can't become empty.
Most systems just mount another filesystem over rootfs and ignore it. The
amount of space an empty instance of ramfs takes up is tiny.
|
These entries are, for all intents and purposes, vestigial, leftovers from the boot process, but they aren't going anywhere, and should be ignored.
The entry for 'rootfs on /' is explained above. The entry for /dev/root, I'd just botch the explanation. Have a quick look at 'ls -alh /dev/root' - you will note it's a symlink to /dev/sd<whatever>
Things may have one name during the initial phases of the boot process, before udev has had its time to work for example, than they do at the end. In the bootup process it is easier to just deal with /dev/root and let the symlink get created than it is trying to figure out partition names and THEN mount. If that makes sense.
_________________
Lost configuring your system?
dump lspci -n here | see Pappy's guide | Link Stash |
|
| Back to top |
|
|
peppev
n00b
Joined: 10 Aug 2009
Posts: 26
Location: Italy
|
| Posted: Sun Mar 13, 2011 10:00 am Post subject: |
|
|
| cach0rr0 wrote: |
These entries are, for all intents and purposes, vestigial, leftovers from the boot process, but they aren't going anywhere, and should be ignored.
The entry for 'rootfs on /' is explained above. The entry for /dev/root, I'd just botch the explanation. Have a quick look at 'ls -alh /dev/root' - you will note it's a symlink to /dev/sd<whatever>
Things may have one name during the initial phases of the boot process, before udev has had its time to work for example, than they do at the end. In the bootup process it is easier to just deal with /dev/root and let the symlink get created than it is trying to figure out partition names and THEN mount. If that makes sense. |
I agree. Should be ignored.
Then why having "/" listed twice by "mount" and "df", from a not
filtered "/etc/mtab" is considered a good idea?
I explored a little bit and a BUG was filed and CLOSED about this topic a while ago.
But if I present to my UNIX users, skilled using shell scripts, a system where "df"
list twice "any" filesystem, they are going to kill me. We have ton of scripts using
the output of standard commands to do any sort of work. They have been working
for decades in many variant of UNIX and POSIX systems, from AIX to FreebSD, from
Solaris to Linux, from CYGWIN to Darwin and this would disrupt them.
Just my 2 cents. |
|
| Back to top |
|
|
robb11
n00b
Joined: 20 May 2011
Posts: 17
Location: Milan, Italy
|
| Posted: Wed May 25, 2011 8:46 am Post subject: |
|
|
| peppev wrote: |
I agree. Should be ignored.
Then why having "/" listed twice by "mount" and "df", from a not
filtered "/etc/mtab" is considered a good idea?
I explored a little bit and a BUG was filed and CLOSED about this topic a while ago.
But if I present to my UNIX users, skilled using shell scripts, a system where "df"
list twice "any" filesystem, they are going to kill me. We have ton of scripts using
the output of standard commands to do any sort of work. They have been working
for decades in many variant of UNIX and POSIX systems, from AIX to FreebSD, from
Solaris to Linux, from CYGWIN to Darwin and this would disrupt them.
Just my 2 cents. |
Well... I have to say it, I agree with you. I have solved editing /etc/init.d/mtab, substituting
| Code: | | grep -v "^[^ ]* / tmpfs " /proc/mounts > /etc/mtab" |
with:
| Code: | | grep -v "^[^ ]* / tmpfs " /proc/mounts | grep -v "rootfs" > /etc/mtab" |
but I consider it just a personal patch.
Cheers,
Robb.
_________________
The Bible says: "A day Apocalypse's Knights will shout with superuser powers: <<rm>> " |
|
| Back to top |
|
|
anest
n00b
Joined: 12 Mar 2007
Posts: 31
|
| Posted: Tue Sep 20, 2011 5:55 pm Post subject: |
|
|
https://forums.gentoo.org/viewtopic-p-6609921.html#6609921
thanks peppev for the solution! its really works. and im wonder why this was not added to distro yet??!
this bug (yes, it is!) driving many people crazy! its MUST be added to distro as default script by replacing old one!
doing this manually every time is just a pain in butt, why no one cares?  |
|
| Back to top |
|
|
anton_kg
Tux's lil' helper
Joined: 10 Feb 2007
Posts: 93
|
| Posted: Wed Sep 21, 2011 6:51 am Post subject: |
|
|
I think you guys can raise your concerns in the following bugs and try to re-open if necessary (I'm no expert):
https://bugs.gentoo.org/show_bug.cgi?id=219038
https://bugs.gentoo.org/show_bug.cgi?id=367637
The current status as bellow:
| Quote: | Jeremy Olexa (darkside) 2011-05-18 00:04:26 UTC
This isn't a bug. Furthermore, it is covered in the migration guide.
http://www.gentoo.org/doc/en/openrc-migration.xml
rootfs entry in /etc/mtab
Previously, the initial rootfs entry was removed from /etc/mtab, and only the
real root / entry was present. The duplicate rootfs item was actually added
back during shutdown. In OpenRC, both entries must be present for full support
of initramfs and tmpfs-on-root. This also means that less writing is required
during shutdown.
|
|
|
| Back to top |
|
|
wcg
Guru
Joined: 06 Jan 2009
Posts: 588
|
| Posted: Wed Sep 21, 2011 4:15 pm Post subject: |
|
|
While I see this in the output of mount, too
(does not show the actual physical partition
mounted on root directory, only the ephemeral
rootfs and the /dev/root symbolic link), nothing has
complained, so apparently either nothing running
depends on being able to find the actual device
mounted on / or it finds it through the /dev/root
symbolic link.
The only thing I wanted to mention is that
the actual device to mount on / should be earlier
in the boot order in the OP's posted /etc/fstab.
You cannot mount /boot, /home, etc before the
root partition is mounted. Without a mounted
root partition containing those directories, those
mount points do not exist.
You can enable swap space in /etc/fstab before
the root partition, because swap space does not depend
on a filesystem mount point, but the actual device
to mount on / should be the next entry.
(My systems always mount partitions in the order that
they are specified in /etc/fstab. The mount program may
be able to rearrange things to mount the root partition
first, but why make it take that path through the code
when one can simply tell it to mount the root partition
first directly in /etc/fstab.)
_________________
TIA |
|
| Back to top |
|
|
anest
n00b
Joined: 12 Mar 2007
Posts: 31
|
| Posted: Sun Oct 30, 2011 6:27 pm Post subject: |
|
|
It's very weird case. On all my *old* installations (servers, routers, desktops. its all been updated to up to day offcourse) the script just simple works!:
| Code: |
mybeast ~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/md3 718965936 110868996 571575580 17% /
rc-svcdir 1024 92 932 9% /lib64/rc/init.d
udev 10240 184 10056 2% /dev
shm 4094272 0 4094272 0% /dev/shm
/dev/md1 132134 14739 110573 12% /boot
mybeast ~ # |
| Code: | FX6850 ~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda3 959221208 903923548 6572056 100% /
udev 4078340 4 4078336 1% /dev
tmpfs 1635512 1160 1634352 1% /run
none 5120 4 5116 1% /run/lock
none 4088776 72052 4016724 2% /run/shm
/dev/sda1 248895 57871 178174 25% /boot
FX6850 ~ # |
but on all my *new* installations (even after all system updates) this script not works any more! WTF!
| Code: | router ~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 239073888 3030308 223899248 2% /
devtmpfs 256836 12 256824 1% /dev
rc-svcdir 1024 68 956 7% /lib/rc/init.d
shm 257000 0 257000 0% /dev/shm
/dev/hda1 254244 6693 234424 3% /boot
router ~ # |
anyone can help to figure out that, please??!
who wants to see this nasty "/dev/root"??? i want my normal /dev/[sh]da3 back!  |
|
| Back to top |
|
|
anest
n00b
Joined: 12 Mar 2007
Posts: 31
|
| Posted: Sun Oct 30, 2011 7:02 pm Post subject: |
|
|
sorry, i overlooked post with symlink solution 
this ln -s /dev/hda3 /dev/root resolved my problem:
| Code: | router ~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 239073888 3030484 223899072 2% /
devtmpfs 256836 12 256824 1% /dev
rc-svcdir 1024 68 956 7% /lib/rc/init.d
shm 257000 0 257000 0% /dev/shm
/dev/hda1 254244 6693 234424 3% /boot
router ~ #
router ~ # ln -s /dev/hda3 /dev/root
router ~ #
router ~ # grep -v "^rootfs" /proc/mounts
/dev/root / ext4 rw,noatime,user_xattr,acl,barrier=1,data=ordered 0 0
devtmpfs /dev devtmpfs rw,relatime,size=256836k,nr_inodes=64209,mode=755 0 0
proc /proc proc rw,relatime 0 0
rc-svcdir /lib/rc/init.d tmpfs rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620 0 0
shm /dev/shm tmpfs rw,nosuid,nodev,noexec,relatime 0 0
/dev/hda1 /boot ext2 rw,noatime,errors=continue 0 0
usbfs /proc/bus/usb usbfs rw,nosuid,noexec,relatime,devgid=85,devmode=664 0 0
router ~ #
router ~ # /etc/init.d/mtab restart
* WARNING: you are stopping a boot service
* Updating /etc/mtab ... [ ok ]
router ~ #
router ~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hda3 239073888 3030484 223899072 2% /
devtmpfs 256836 12 256824 1% /dev
rc-svcdir 1024 68 956 7% /lib/rc/init.d
shm 257000 0 257000 0% /dev/shm
/dev/hda1 254244 6693 234424 3% /boot
router ~ #
|
but i wonder why this symlink not created just automatically by system? i still thinking its a BUG. |
|
| Back to top |
|
|
Hu
Moderator
Joined: 06 Mar 2007
Posts: 21607
|
| Posted: Sun Oct 30, 2011 7:26 pm Post subject: |
|
|
| If your system is fully up to date, you should not have any hdX device nodes left. Updated systems should be using the PATA/SATA layer, which does not use the hdX naming convention. |
|
| Back to top |
|
|
anest
n00b
Joined: 12 Mar 2007
Posts: 31
|
| Posted: Sun Oct 30, 2011 8:48 pm Post subject: |
|
|
i was wrong - symlink just works until next reboot 
after reboot again i see this nasty /dev/root and not /dev/hda3 any more
any solution? |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
|
Kernel & Hardware
