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msfu
n00b
Joined: 29 May 2019
Posts: 4
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 Posted: Wed May 29, 2019 5:15 pm Post subject: Could not find the root block device in . |
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Hi there,
I installed Pentoo (pentoo-full-amd64-hardened-2019.0_-r1) on my external HDD and it works under the old Dual Core Notebook which I used for the Install. But now when i try to boot the HDD under a new ASUS 64 bit Win10 machine it fails to boot and gives me the Error Message:
| Code: | The filesystem mounted at /dev/sdb2 does not appear to be valid /, try again
Could not find the root block device in .
Please specify another value or:
-press Enter for the same
-type "shell"for a shell
-type"q" to skip |
What I did after that was changing the devices to UUID in the /etc/fstab but nothing happens. There is the same Error Message.
Does anybody know what I can do next? |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54644
Location: 56N 3W
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| Posted: Wed May 29, 2019 5:26 pm Post subject: |
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msfu,
| Code: | | Could not find the root block device in . |
lists all the block devices that the kernel can see.
In this case, none at all.
As /etc/fstab is on the root partition, it cannot yet be read.
Mounting root depends on the kernel being told where root is, with the root= parameter on the kernel command line in grub.cfg
There is another wrinkle or two for USB external drives. The USB drivers need to be started before root can be mounted. The default startup sequence is to mount root, then start USB.
That's a problem for root on USB.
The fix is to add to the kernel command line in grub.cfg
If you will be in the habit of moving this external drive between systems, use root=PARTUUID= on the kernel command line.
The kernel understands PARTUUID= without the aid on an initrd and it won't change from system to system.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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NeddySeagoon
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Joined: 05 Jul 2003
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Location: 56N 3W
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| Posted: Wed May 29, 2019 5:27 pm Post subject: |
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Moved from Installing Gentoo to Unsupported Software.
As Pentoo is not Gentoo.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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msfu
n00b
Joined: 29 May 2019
Posts: 4
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| Posted: Wed May 29, 2019 5:55 pm Post subject: |
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Okay, sorry for that nooby question but i tried both and it doesn`t work.
Can you tell me what is the exact code and how to write in grub.cfg file?
Because when I type in : rootwait and save the grub.cfg file and then type grub2-mkconfig -o /boot/grub/grub.cfg
it says /usr/sbin/grub2-mkconfig: line 243: /boot/grub/grub.cfg.new: No such file or directory
What have I forgotten? |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54644
Location: 56N 3W
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| Posted: Wed May 29, 2019 7:42 pm Post subject: |
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msfu,
To start with, don't change the grub.cfg until you know it works.
Choose the entry you want to boot but press the 'e' key to edit the in memory copy of the boot stanza.
There will be on screen instructions.
At the end of the kernel line, add a space followed by rootwait
Now boot.
If the root filesystem never appears it will wait forever.
rootdelay=7 will make the kernel wait 7 seconds for root to appear, then comtine trying to mount it anyway.
rootwait, is the fastest, rootdelay=<sec> will generate a panic when it times out. The messages may be useful.
You can change root= in the same way.
will tell the PARTUUIDs
Do not use UUID here unless you have an initrd that understands UUID.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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Jaglover
Watchman
Joined: 29 May 2005
Posts: 8291
Location: Saint Amant, Acadiana
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msfu
n00b
Joined: 29 May 2019
Posts: 4
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| Posted: Wed May 29, 2019 8:43 pm Post subject: |
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Okay, I resetted the UUID in the /etc/fstab to /dev/sda1 and so on...
If I press e in the boot menu there comes a screen in which the last line is maybe the Kernel line... i really don`t know
i added a space and then rootwait and reboot but then the Display says Error invalid filename rootwait
Then there is Kernel Panic and it reboots after 60 seconds... I also tried rootdelay=7. The same Error.
@Jaglover on the old System it was connected via USB 2.0 and it still works. On the new machine its connected via USB 2.0, too. |
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 54644
Location: 56N 3W
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| Posted: Wed May 29, 2019 9:11 pm Post subject: |
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msfu,
The kernel command line starts with the word kernel.
This is from grub-legacy but the kernel and initrd lines are the same.
| Code: | kernel /boot/5.0.7-gentoo root=PARTUUID=01e92c83-e4d9-496b-8efa-33f83a14bbd5 rootdelay=5 video=intelfb:mttr:3,ywrap,1024x600-32@60 net.ifnames=0
initrd /boot/early_ucode.cpio
initrd /boot/fbsplash-initrd |
This system boots from USB2 too.
| Code: | | kernel /boot/5.0.7-gentoo |
Tells grub to load the file /boot/5.0.7-gentoo as the kernel.
The rest of the line is passed to the kernel.
| Code: | | root=PARTUUID=01e92c83-e4d9-496b-8efa-33f83a14bbd5 rootdelay=5 video=intelfb:mttr:3,ywrap,1024x600-32@60 net.ifnames=0 |
root=PARTUUID=01e92c83-e4d9-496b-8efa-33f83a14bbd5 in partition UUID (not filesystem UUID) to use for the root filesystem..
rootdelay=5 wait 5 seconds for USB to start.
video=intelfb:mttr:3,ywrap,1024x600-32@60 set up the console framebuffer
net.ifnames=0 turn off persistent network naming.
| Code: | # blkid
/dev/mmcblk0p1: UUID="76378f34-1dc3-45c1-a4e1-2d01d2949764" TYPE="ext2"
/dev/sda1: UUID="2d6bdd2d-bfd7-4860-a289-7045dc00620a" TYPE="ext2"
/dev/sda2: UUID="5e1c3bfc-c16d-4b1e-bee8-374ce6f46385" TYPE="swap"
/dev/sda3: UUID="5ce8691c-eaab-46de-8498-267b30d25e0c" SEC_TYPE="ext2" TYPE="ext3"
/dev/sdb1: UUID="ed6fedb7-ee7e-486b-a51a-a5a9fbf8cc65" TYPE="ext2" PARTLABEL="netbook_boot" PARTUUID="139f2af5-9841-455e-8276-e2fc4b19dce5"
/dev/sdb2: UUID="43584678-7555-4bd6-b99e-5bab5e2cdde8" TYPE="swap" PARTLABEL="swap" PARTUUID="4421a161-7097-4eb0-a9cb-9840acc73eb9"
/dev/sdb3: UUID="449af2b1-485e-4042-8eff-362887bb30c3" TYPE="ext4" PARTLABEL="netbook_root" PARTUUID="01e92c83-e4d9-496b-8efa-33f83a14bbd5" |
That tells that root is /dev/sdb3 but /dev/sdb3 is not portable. PARTUUID="01e92c83-e4d9-496b-8efa-33f83a14bbd5" finds it wherever it is.
Its similar in /etc/fstab. /dev/sdXY names are not portable. UUID, PARTUUID or filesystem LABEL all work there.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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msfu
n00b
Joined: 29 May 2019
Posts: 4
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| Posted: Thu May 30, 2019 8:33 am Post subject: |
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Thanks a lot for your help!
I Tried it with UUID and rootdelay=5 in the kernel line.
The kernel line now looks like this:
| Code: | | GRUB_CMDLINE_LINUX="root=dev/ram0 real_root=UUID=a21bb1a9-7f1d-480d-a27b-b084426cc586 rootdelay=5 video=uvesafb:mtrr:3,ywrap,1024x768-16 console=tty1 net.ifnames=0 ro" |
Afterwards i typed in the Terminal: grub2-mkconfig -o /boot/grub/grub.cfg
And all what it says is: /usr/sbin/grub2-mkconfig: line243: boot/grub/grub.cfg.new: No such file or directory
Is that right? |
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NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54644
Location: 56N 3W
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| Posted: Thu May 30, 2019 6:58 pm Post subject: |
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msfu,
Is /boot mounted?
I don't use gub2. For testing you can use grubs built in editor.
editing /boot/grub/grub.cfg by hand works but its not recommended as your next grub2-mkconfig -o /boot/grub/grub.cfg will remove your edits.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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Unsupported Software
