No Root File System Is Defined [Here Are Solutions]

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This wiki article will show you how to install Funtoo on ZFS (rootfs).

This page is unofficial. ZFS as root filesystem is not supported under Funtoo Linux, mainly because it has limited benefit. ZFS is still supported but boot on a non-ZFS filesystem first. See ZFS.

Configure your network according to the main installation guide.

Set the root password.

Exit the chroot and export your ZFS storage pool.

(chroot) #

zpool export rpool

Restart to boot into Funtoo Linux on a ZFS root!

ZFS has many interesting features not covered by this guide.

Useful information and instructions can be found in the online reference manuals. See man zpool and man zfs.

ZFS on Linux — http://www.zfsonlinux.org

ZFS — Gentoo Wiki — https://wiki.gentoo.org/wiki/ZFS

1 Introduction

Several common embedded file system construction methods: busybox, yocto, builroot, I think they are not as convenient as Ubuntu, powerful guarantee system, strong community support, you can directly install new software packages with apt-get install. This article describes how to build a complete ubuntu system based on Ubuntu-base. For archlinux installed or builtLFSFriends of this method can’t be more familiar with.

Ubuntu supports many architectures, arm, X86, powerpc, ppc, etc. This article is mainly based on X86_64 as an example, arm and arm64 also give simple production steps, and other architectures are similar in operation.

ZFS is designed for 64-bit systems. We only recommend and support 64-bit platforms and installations!

ZFS v07.5 (latest in ports as of 18 Jan 2018) is compatible with kernel versions 2.6.32 — 4.14

The guide is under rewrite

It is recommended to give the entire disk to ZFS. As such, this guide will only show how to install ZFS on the whole disk, using legacy boot. Installing on UEFI requires a separate partition for /boot, formatted as FAT32, and is out of the scope of this guide, even though installation on UEFI is certainly possible. Also, this guide will not cover anything related to encryption (native encryption is available: https://github.com/zfsonlinux/zfs/commit/b52563034230b35f0562b6f40ad1a00f02bd9a05).

Downloading the ISO (With ZFS)

In order to install Funtoo on ZFS, you will need an environment, such as live media, that provides the ZFS tools. This guide will utilize the Ubuntu Desktop 16.04 (live) DVD for amd64.

Now that the initial ZFS pool and datasets have been created, we can unpack the stage 3 tarball and proceed with basic system installation. This part does not differ much from a regular Funtoo Linux installation (https://www.funtoo.org/Install#Installing_the_Stage_3_tarball). We recommend using funtoo-current stages for ZFS.

tar xpf stage3-latest.tar.xz

Now, we need to create a chroot environment:

mount -t proc none proc
mount —rbind /sys sys
mount —rbind /dev dev

An important step is to copy the ZFS cache into the chroot. The ZFS cache was created when rpool was created with the -o cachefile=/tmp/zpool.cache flag.

mkdir -p /mnt/funtoo/etc/zfs
cp /tmp/zpool.cache /mnt/funtoo/etc/zfs/zpool.cache

You will also want to copy over resolv.conf in order to have proper resolution of Internet hostnames from inside the chroot:

cp /etc/resolv.conf /mnt/funtoo/etc/

We are now ready to chroot.

chroot /mnt/funtoo /bin/bash
export PS1=»(chroot) $PS1″; cd

Linux is a versatile and open-source operating system that you can use on your computer, server, or embedded device. One of the most common errors when using Linux is the “No Root File System is Defined” error.

Several factors can cause this error, but most often, it is caused by an incorrect or missing root file system. If you are getting this error, don’t worry. In this article, we will show you how to fix the “No Root File System is Defined” and make your computer run normally and able to access the correct partition.

If by any chance you happen to receive the “No Root File System is Defined” error, it means that during the installation process, Ubuntu/Linux could not detect the root partition when it was trying to install the OS.

Partitions are sections of your computer’s hard drive that you can use to keep your data organized. The root partition is where the core files of your Ubuntu/Linux installation are located.

For Ubuntu/Linux to be installed correctly, it needs to be able to find the root partition. If it can’t find the root partition, you will receive the “No Root File System is Defined” error.

Below are the leading causes of this error:

Forgot to reset password?

You will need to chroot into your Funtoo on ZFS root installation if you forgot to set the root password. Repeat the earlier instructions to load the the live CD/USB, including the installation of ZFS kernel modules.

When the ZFS kernel modules are loaded, your existing ZFS Storage Pool (rpool) will be imported automatically. This will also result in an attempt to mount the various ZFS filesystems that you created. Mounting your root partition (/) will fail since this location is not empty; / is allocated to the live CD/USB distribution!

pool: rpool
state: ONLINE
scan: none requested
config:

NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF ONLINE 0 0 0

errors: No known data errors

To get around this issue, first, manually export the pool.

zpool export rpool

no pools available

zpool import -o cachefile=/tmp/zpool.cache -R /mnt/funtoo -d /dev/disk/by-id/ rpool

Will not mount on first reboot?

Things to check:

Rpool is ‘busy’ on zpool export

This happens when swapon is used.
Swap must be turned off to free the pool for export.

Unable to add universe repository in Ubuntu?

Take a snapshot of your Funtoo at installation.

The use of snapshots, including sending snapshots as a method of backup, are not covered in this guide. See Further Reading.

ZFS Adjustable Replacement Cache (ARC) size

The Adjustable Replacement Cache (ARC) is a fundamental part of ZFS. Refer to this article by Aaron Toponce for details on how to set up an ARC.

Without configuration, ZFS will use up to 50% of your memory (RAM) for the ARC. It is possible to change this maximum. There are different ways to achieve this on both a temporary and persistent basis. One such way is to create and edit the file /etc/modprobe.d/zfs.conf, which affects the ZFS kernel module.

/etc/modprobe.d/zfs.conf — set maximum ARC size to 4 GiB

options zfs zfs_arc_max=4294967296

where zfs_arc_max is set to a value in Bytes. After configuring this file, re-generate the initramfs. Rebooting will then apply this change.

To apply this change immediately without a reboot, issue the command:

After Kernel or ZFS updates

The default Funtoo Linux kernel (sys-kernel/debian-sources) does not automatically build a ZFS-capable initramfs. Similarly, the package sys-fs/zfs and its dependencies do not automatically build a ZFS-capable initramfs.

After each kernel update, you must recreate an initramfs. Similarly, sys-fs/zfs updates also require you to regenerate an initramfs. This is especially true for updates to sys-fs/zfs that introduce new storage pool features. Neglecting to update your initramfs will make your system unbootable.

First, rebuild sys-fs/zfs, sys-fs/zfs-kmod and sys-kernel/spl:

emerge —ask —verbose -1 zfs zfs-kmod spl

genkernel initramfs —no-clean —no-mountboot —makeopts=-j4 —kernel-config=/usr/src/linux/.config —zfs

mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1

Finally, repeat the earlier instructions for generating /boot/grub/grub.cfg and manually adding the new initramfs as initrd to the generated /boot/grub/grub.cfg.

We are letting ZFS automatically partition the drive. This is ideal for our example using a single disk and legacy (BIOS) boot.

Creating of pool

Create a ZFS Storage Pool using a single whole disk.

The options used here are

Please note that the options ‘ashift’ and ‘cachefile’ are preceded with a lowercase ‘-o’, while ‘normalization’ and ‘atime’ are preceded with an uppercase ‘-O’.

Without additional options, this will create our storage pool and enable all ‘features’ available under version 0.6.5.6. The pool will be automatically mounted at the (temporary) location /mnt/funtoo.

To confirm the presence of our newly created pool:

Create ZFS Datasets

Now, we will create one or more ZFS datasets within our storage pool. These will contain Funtoo Linux.

Create the Root file system (Required)

zfs create -o mountpoint=none -o canmount=off rpool/ROOT
zfs create -o mountpoint=/ rpool/ROOT/funtoo

Create optional Datasets

zfs create -o mountpoint=/home rpool/HOME

zfs create -o mountpoint=none -o canmount=off rpool/FUNTOO
zfs create -o mountpoint=/var/tmp/portage -o compression=lz4 -o sync=disabled rpool/FUNTOO/build

Swap on ZFS

zfs create -V 2G -b $(getconf PAGESIZE) -o logbias=throughput -o sync=always -o primarycache=metadata rpool/swap

To confirm the presence of the filesystems that we have created:

Make the root filesystem bootable

Do not skip this!

When booting from ZFS, you must specify a boot device and a root file system within the pool that was identified by the boot device. By default, the dataset selected for booting is the one identified by the pool’s bootfs property.

zpool set bootfs=rpool/ROOT/funtoo rpool

Original writeup here (with some bugs corrected):

But the steps is applicable to any hardware: i386, amd64, ppc, arm, mips etc.

First download the Ubuntu base from here (here we assumed for amd64, but you can always download images for other platform and :

Next is to create the rootfs image:

Some repetition may be needed here (until you get the size right). By that I mean the the “apt-get install” command below can be successfully executed – to include all the basic debian packages.

For Ubuntu 18.04 amd64, the estimated required size is about 1G.

So create a 1G rootfs empty image:

sudo dd if=/dev/zero of=rootfs.img bs=1024 count=1M

sudo mkfs.ext4 -F -L linuxroot rootfs.img

sudo mkdir /mnt/tmpdir

sudo mount -o loop rootfs.img /mnt/tmpdir

sudo tar zxvf ubuntu-*.tar.gz -C /mnt/tmpdir #### (unpacking the tar.gz file downloaded from cdimage.ubuntu.com above).

sudo cp /etc/resolv.conf /mnt/tmpdir/etc/

sudo mount -t proc /proc /mnt/tmpdir/procsudo mount -t sysfs /sys /mnt/tmpdir/syssudo mount -o bind /dev /mnt/tmpdir/devsudo mount -o bind /dev/pts /mnt/tmpdir/dev/pts

sudo chroot /mnt/tmpdir

Inside the chroot environment (“sudo” does not exists in ubuntu base):

apt-get updateapt-get install language-pack-en-base sudo ssh net-tools ethtool wireless-tools ifupdown network-manager iputils-ping rsyslog htop vim xinit xorg alsa-utils —no-install-recommends

Inside the rootfs:

You may want to setup root password as well, just in case you may be interested in going as root, as “sudo” is not configured by default.

Set up hostname:

127.0.0.1 localhost127.0.0.1 myhost

##//set up timezonedpkg-reconfigure tzdata

sudo umount /mnt/tmpdir/procsudo umount /mnt/tmpdir/syssudo umount /mnt/tmpdir/dev/ptssudo umount /mnt/tmpdir/dev

Assuming the present rootfs image is named as “rootfs.img”:

Booting up in the latest kernel I have compiled:

qemu-system-x86_64 -m 1024M -nographic -kernel $kernel -append «$append» -hda $rootfs -net nic

Have you received «no root file system is defined» when installing Ubuntu? Why will you get this error? How to define a root file system? What factors will prevent you from defining a root file system? You will get answers from the post from MiniTool Partition Wizard.

On This Page :

No Root File System Is Defined

Some people report that they have encountered error “no root file system is defined” while installing Ubuntu. This error will happen not only when you decide to install Ubuntu alongside Windows, but also when you decide to erase disk and install Ubuntu.

How to Define a Root File System

In the pop-up window, the most important thing is that you should choose “/” as the mount point. As for the type and location of the partition, you can choose as your will.

2 Cases Where You Will Fail to Create the Root Directory

Ubuntu can only create the root directory using free space or a Linux partition with file systems liek EXT4, EXT3, etc.

Some people who want to install Ubuntu alongside Windows may know shrink a Windows partition to make room for Ubuntu. But they then create a FAT32, NTFS, ore RAW partition on the unallocated space (not an EXT partition).

In this case, please right-click on the partition and choose Delete. Then, the partition will become free space.

For people who have not shrunk Windows partition, please shrink them first.

Case 2. There Are Already 4 Primary Partitions

If your disk is an MBR disk, it can only hold up to 4 primary partitions or 3 primary partitions + 1 extended partition.

If there are already 4 primary partitions on the MBR disk, you can’t use the free space to create the root partition. Similarly, this will also fail if there are 3 primary partitions + 1 extended partition on the MBR disk and the free space is not next to the extended partition.

Tip: If the free space is next to the extended partition, you can create the root directory as a logical primary.

To solve this issue, the simplest way is to delete a primary partition. But please move data to a safe place first. If you don’t want to delete a partition, you can try converting the MBR to GPT style. This will also solve the problem.

Linda has been working as an editor at MiniTool for 5 years. She is always curious about computer knowledge and learns it crazily. Her articles are simple and easy to understand. Even people who do not understand computer can gain something. By the way, her special focuses are disk management, data recovery and PDF editing.

Even when you know a lot about computers and their programming, some errors can annoy you. In this article, we’ll take a look at one such case. We’ll discuss the No Root File System is defined error. This error usually appears while trying to install Ubuntu or other Linux distributions. I will explain all the needed information about the Root File System and 3 ways to fix this problem. Get aboard.

To understand the issue better, we shall briefly know about Root File System first, and then we’ll move up on the causes of this.

What is the Root File System?

root filesystem that is placed on the same partition on which the  is situated. It is the filesystem on which all the other filesystems are attached upon as the system starts up or booted.  For further knowledge, a partition is a theoretically independent section of a hard disk drive (HDD). A filesystem is a hierarchy of directories that are used to organize files on a computer system. It is also known as a directory tree. When you are on Linux , the directories start with the root directory, which further contains a series of subdirectories. Then each subdirectory also contains further subdirectories. A variant of this definition is the component of the entire directory tree that is located on a single partition or disk.

How does the Root File System work?

You must have caught your fault by now. This error usually occurs with Ubuntu as people don’t have much information about Linux and its partitions. Now we shall move further to the solutions of this problem.

Create a Linux Partition and Assign a Root Partition

Step-1: Go to the Installation type page, choose a free partition.

Step-2: Now click on the + sign to add a partition. When you click on the + sign, the Create partition window will appear.

Step-3: In the window,  go to the Size field, the default will be the full size of the partition. Enter a value here in MB.

Step-4: Next, choose the type of partition, Primary Logical

Step-5: Next, on the Location for the new partition, choose the Beginning of spaceEnd of space

Step-6: Then choose a file system. You can select the default, Ext4 journaling

Step-7: Finally, select a Mount point. The Mount point drop-down menu will show you certain options. Here, for a root partition, select /.

After finishing this, click on Ok.

Done. Check if this solved your problem.

Delete Existing Windows Partition

Note: You can also modify the partition.

Step-1: First you have to delete the partition. To do this, right-click on it and choose Delete

Step-2: Now choose Change to change the file system to a Linux file system.

Step-3: When you click on Change, a dialog box will load. In order to change the file system to a Linux file system, click on the drop-down menu. Then select a file system and then click on Ok.

Now check if the problem vanishes with this solution.

Define a Root Partition

Step-1: Firstly, Right-click on the partition you wish to use as root and click on Change. You can also double-click on the partition.

Step-2: When the Edit partition option loads, beside Mount point, click on the drop-down menu and select /.

Step-3: Finally, click on Ok to save the changes

You will now be able to continue with your Ubuntu installation. Just choose the partition you created, check the column, and then click on Install Now.

Conclusion

These were the 3 Best Methods to resolve the No Root File System is defined issue. In case, you are still in trouble, Id’ suggest visiting Ubuntu Forums to seek further help. For any queries, doubts or suggestions, feel free to visit the Comments section. Hope I helped you.

Install the ZFS packages and sync the portage tree, if required:

emerge —ask sys-fs/zfs

rc-update add zfs-import boot
rc-update add zfs-mount boot

Add another two services to the default runlevel:

rc-update add zfs-zed default

Create a ZFS-friendly initramfs

The Funtoo stage3 includes a linux kernel and initramfs. The initramfs is designed to mount and start Funtoo Linux on a variety of file systems. The initramfs contained within the stage3 will not mount and start Funtoo in our ZFS storage pool. We must create an updated ‘ZFS-friendly’ initramfs.

Optional: Update to the latest No results:

emerge —oneshot sys-kernel/genkernel

Use genkernel to create an initramfs capable of mounting our ZFS Storage Pool via the —zfs switch. Adjust —makeopts according to the number of available threads:

Confirm the presence of the new initramfs:

mv initramfs-genkernel-x86_64-4.5.2-1 initramfs-debian-sources-x86_64-4.5.2-1

/boot/initramfs-debian-sources-x86_64-4.5.2-1

Installing GRUB 2

GRUB 2 must be built with support for ZFS Storage Pools on a single disk. This is achieved using the ‘libzfs’ USE flag.

If you have defined GRUB_PLATFORMS in your /etc/portage/make.conf, please ensure that it includes ‘pc’: e.g. GRUB_PLATFORMS=»efi-64 pc».

This is required for booting in BIOS (non-UEFI) mode, as described in this guide.

Now, install GRUB:

Configuring the Bootloader

When zpool created our storage pool (rpool), it created partitions under a GPT scheme. In order to boot Funtoo Linux on a GPT partion under legacy (BIOS) boot, sys-boot/grub requires a small partition, called a BIOS boot partition. By design, ZFS (zpool) left a very small unpartitioned space at the beginning of the disk. We will use sgdisk, which is part of sys-apps/gptfdisk, to format this free space into a BIOS boot partition.

sgdisk -a1 -n2:48:2047 -t2:EF02 -c2:»BIOS boot partition» /dev/disk/by-id/ata-Samsung_SSD_840_EVO_120GB_123456789ABCDEF

To avoid problems with GRUB, use partx to refresh the list of partitions that are ‘seen’ by the kernel. Do this for each drive (/dev/sda, /dev/sdb, etc.).

partx -u /dev/sda

A quick check to verify that GRUB 2 sees/supports ZFS:

Installing GRUB2 to disk is as easy as:

Installing for i386-pc platform.
Installation finished. No error reported.

Now, it’s time for us to create grub’s configuration file. First, we must edit a few GRUB 2 settings in /etc/default/grub:

Replace the line

/etc/default/grub — before

/etc/default/grub — after

Now, create GRUB 2 configuration file:

If grub-mkconfig cannot find the initrd image, manually add initrd to the generated /boot/grub/grub.cfg, below the linux line:

/boot/grub/grub.cfg — adding initrd below the linux line

A quick check to verify that the GRUB ZFS module is in place:

Creating a bootable USB from ISO (From a Linux Environment)

The size of the iso is approximately 1.5 GB.

Insert your blank USB media into a USB port. Then, inspect the kernel ring buffer with dmesg to identify the device name of your USB storage.

A quick and easy way to create a bootable USB is to write the ISO data to the USB device using dd.

dd if=/path/to/iso/ubuntu-16.04-desktop-amd64.iso of=/dev/sdg bs=4K

Once this has completed, remove and use this USB to boot the target system that will receive Funtoo Linux.

Booting the ISO

Once the desktop has loaded, open the search bar by left-clicking on the top-left icon («Search your computer»). Pressing Alt+F1 should also open this search bar. Search for and open the Terminal application.

Verify that the ZFS kernel module has loaded.

Prepare the host system

/dev/sda1 #UEFI partition 500MB
/dev/sda2 #Host system root partition 20GB
/dev/sda3 #Used to build ubuntu-base 5GB

Create loop file and partition

The loopback file system is a very interesting part of the Linux system. We usually create a file system on the device (such as a disk partition). These storage devices can be used in the form of device files, such as /dev/device_name. In order to use the file system on the storage device, we need to mount it to some directories called mount points. The loopback file system refers to those inFile instead of physical deviceThe file system created in. We can mount these files as a file system on the mount point. This actually allows us to create logical disks in files on physical disks.

Our purpose: create a loop file to simulate a physical disk of 10GB in size, and divide it into two areas in the loop mirror:

Create an image file

That is to create a file with a size of 10G.

if/dev/zero ofubuntu_base.img bs1G count10
Recorded 10+0 reading
Recorded the write out of 10+0
10737418240 bytes 11 GB, 10 GiB copied, 84.1916 s, 128 MB/s

usemkfsCommand to format a 1GB file into ext4 file system:

$ ubuntu_base.img
loobackfile.img: Linux 1.0 ext4 filesystem data, UUID3be1775c-8976-445d-9134-8daabb2bade7 extents 64bit large files huge files

Now you can mount the loopback file:

/mnt/loopback
-o loop ubuntu_base.img /mnt/loopback

-o loopUsed to mount the loopback file system.

This is actually a quick way to mount, we don’t need to manually connect any devices. But internally, this loopback file is connected to a file called/dev/loop1orloop2On the device.

We can also do it manually:

losetup /dev/loop1 ubuntu_base.img
/dev/loop1 /mnt/loopback

You can also use the path of the device file as a parameter of the umount command:

The above is the method of using the entire file as a partition, but our purpose is to divide the file into multiple areas and continue.

Create a partition

Create partition can be usedfdiskorpartedTools, I prefer to useparted, Very convenient for setting up the boot partition.

$ parted ubuntu_base.img
GNU Parted 3.2
Use /home/work/loobackfile.img
Welcome to GNU Parted Input Get a list of commands.
parted

Create a new UEFI partition:

For the UEFI boot mode, first set the creation label to msdos;

parted mklabel msdos

Create a partition size of 500M:

partedmkpart primary fat32 0 500MB

Check the newly created partition, the partition number is 1:

parted p
Model: file
Disk /home/work/ubuntu_base.img: 10.7GB
Sector size logical/physical: 512B/512B
Partition table: msdos
Disk Flags:

Number Start: End Size Type File System Logo
1 512B 500MB 500MB primary fat32 lba

parted

Set the partition as the boot (UEFI boot) partition:

parted 1 boot on
parted p
Model: file
Disk /home/work/ubuntu_base.img: 10.7GB
Sector size logical/physical: 512B/512B
Partition table: msdos
Disk Flags:

Number Start: End Size Type File System Logo
1 512B 500MB 500MB primary fat32 boot, lba

parted

Pass after settingpThe command can be seen, there are more signsBootSign.

Create the root partition with the remaining space:

parted mkpart primary ext4 500MB 100%

Now that the two partitions are created, usepView,qSave and exit:

parted p
Model: file
Disk /home/work/ubuntu_base.img: 10.7GB
Sector size logical/physical: 512B/512B
Partition table: msdos
Disk Flags:

Number Start: End Size Type File System Logo
1 512B 500MB 500MB primary fat32 boot, lba
2 500MB 10.7GB 10.2GB primary ext4 lba

Map and format the partition device

The image file has been divided into two areas, but it has not been formatted. To format the two internal partitions, you need to mount the two partitions to the device first.

There is a faster way to mount all the partitions in the mirror——kpartx. It is not installed in the system by default, you have to install it using the package manager:

kpartx -v -a ubuntu_base.img
add map loop0p1 253:0: 0 976562 linear 7:0 1
add map loop0p2 253:1: 0 19994624 linear 7:0 976896

The partition in the disk mirroring with this command is/dev/mapperA mapping is established between the devices in, and then these devices can be formatted/mounted.

Format two partitions:

$ mkfs.fat -F 32 /dev/mapper/loop0p1 #loop0p1 Partition 1 of the loopback device
$ mkfs.ext4 /dev/mapper/loop0p2 #loop0p1 Partition 2 of the loopback device

Mount the partition

After the format change is complete, two partitions can be mounted:

$ /mnt/loopback
$ /dev/mapper/loop0p2 /mnt/loopback #Mount the root partition
$ -p /mnt/loopback/boot/efi
$ /dev/mapper/loop0p1 /mnt/loopback/boot/efi #Mount uefi boot partition

2 Mount the new partition

Format the target partition and mount it to/mntDirectory, if it is mounted in another directory, all commands after it need to be changed:

mkfs.ext4 /dev/sda3
/dev/sda3 /mnt

willubuntu-base-16.04.6-base-amd64.tar.gzUnzip to/mnttable of Contents:

-xpvf ubuntu-base-16.04.6-base-amd64.tar.gz -C /mnt

Note: You need to retain the file permissions and owner in ubuntu-base, root permissions or sudo operation is required when decompressing, and use-pParameter reservation permission.

3 Configure target Ubuntu source

There is a default ubuntu official source in ubuntu-base. If you are connected to the Internet and the speed of access to the official source is not restricted, you do not need to change it. Configuration file/etc/apt/sources.listReplace the source,The host system in this article is consistent with the hardware architecture and version of the system to be built, so just copy it directly。

3 Configure DNS

Networking is required to enter the target environment, DNS needs to be configured first, and host system files are copied/etc/resolv.confTo/mnt/etc/Under contents:

3 Configure user to create default profile

-R /etc/skel /mnt/etc/

3 Enter the chroot environment

-v —bind /dev /mnt/dev

Mount the virtual file system:

-vt devpts devpts /mnt/dev/pts -o gid5,mode620
-vt proc proc /mnt/proc
-vt sysfs sysfs /mnt/sys
-vt tmpfs tmpfs /mnt/run

Enter the chroot environment:

The linux distribution archlinux provides a script to automate chrootarch-chroot, Including automatic configuration of DNS files, automatic mounting of virtual file systems and other operations, it is very convenient to maintain the linux system, and it is directly executed without mounting and other operations when chrooting:

arch-chrootIt is the package of Method 1, in addition to the detection and pre-configuration of the target system, the source code is shown in the appendix.

How To Fix “No Root File System Is Defined”?

When you receive the “No Root File System Is Defined” error message, your computer cannot find the file system’s root directory. It can prevent you from accessing your files and your computer from booting up. There are a few things you can try to fix this problem.

Create The Linux Partition And Assign It As Root

You only need to create a Linux partition and assign it as root to solve the error. This helps when the root directory needs to be assigned correctly.

Delete Windows Partition That Exists

When you choose a FAT or FAT32 while installing Linux, you will get the error ‘No Root File System is Defined.’ In that case, you need to delete the Windows partition and create a new one. The partition will appear as free after you delete it.

You can use the fdisk tool to create a new partition on your hard drive and set it as the root filesystem. This helps the computer to find the correct location of the root directory. The no partition should be represented using (/) and as mount in case of /etc/fstab.

Arch-chroot source code

Please abide by the relevant open source agreements.

Install various desktops (optional)

According to the needs of ubuntu various desktop environments, you can choose one, or you can install multiple at the same time, and use systemd to select the login manager to log in to the corresponding desktop.

GDM-GNOME login manager;

SDDM -QML-based display manager and the successor of KDM; recommended for Plasma and LXQt;

XDM -X display manager, support XDMCP;

LightDM -Cross-desktop display manager, you can use various front-ends written in any toolkit, and Ubuntu 16.04 uses this manager by default.

1 Install Lubuntu’s custom LXDE

The login manager is gdm, and xdn needs to be installed first.

sudo apt-get install gdm
sudo -y —no-install-recommends ubuntu-gnome-desktop

3 Install xfce desktop environment

xfce is a lightweight desktop. Its login manager is xdm, and xdn needs to be installed first.

apt-get install -y xdm

Install desktop environment

apt-get install -y —no-install-recommends xubuntu-desktop

Start the desktop manager at boot.

systemctl enable xdm

4 Install mate desktop

sudo apt-get install ubuntu-mate-core
sudo apt-get install ubuntu-mate-desktop

Purpose

Starting from ubuntu-base, the smallest file system of ubuntu, build a complete system with X-windows.

Install the software

update
upgrade
locales

linux-headers-4.4.0-164-generic linux-image-4.4.0-164-generic linux-modules-4.4.0-164-generic

2 Install X-window

So far, the system can run basic graphics programs.

Frequently Asked Questions

A root partition is a section of a hard drive dedicated to housing the files and data associated with an operating system. The root partition is typically the largest partition on a hard drive and is generally used to store the operating system files. In some cases, the root partition may also be used to store application files.

How Much Is A Root Partition?

A root partition is the main partition on a hard drive where the operating system is installed. The size of a root partition depends on many factors, such as the size of the hard drive, the amount of available space, and the needs of the operating system.

It is crucial to consider the root partition size when installing a new operating system or to upgrade an existing one. Otherwise, the system may need more space to function correctly.

How Much Space Do I Need For A Root Partition?

You should allocate more space for the root partition if you have a larger hard drive. Remember that the root partition size will also affect the disk space available for other partitions, such as the home partition.

Do I Need A Separate Home Partition?

If you’re new to Linux or want to try it out, you may wonder if you need to create a separate home partition. The short answer is: it depends. Suppose you’re planning on using Linux as your primary operating system or have a lot of data you want to keep separate from your operating system. In that case, creating a separate home partition is a good idea.

Otherwise, you can get away with just using a single partition for your entire system.

There are a few benefits to creating a separate home partition:

What Is The Root Of The USB?

The root of a USB is the top-level directory of the drive. In other words, it is the starting point from which all other directories and files on the drive are accessed. The root is typically represented by a slash (/), although some systems may use a different character, such as a backslash ().

The root directory can also be used to store files. However, storing files in subdirectories is generally considered good practice, as this can help keep the drive organized.

What Is Root File System In Linux?

The root file system is the file system that contains all the necessary files and directories for the Linux kernel to operate. It is typically mounted on “/” (the root directory). The bootloader usually initializes the root file system (such as GRUB or LILO). Any other file systems are usually mounted on directories under the root file system, such as /home or /usr.

If you are new to Linux, you might wonder what all this talk about the root file system is. The root file system is the most important part of a Linux operating system. It contains all the files and directories for the Linux kernel to operate. The root file system is typically mounted on “/” (the root directory).

How To Create A Root File System In Linux?

You can create a root file system in Linux using various methods. One common method is using a ” dd ” tool to create an image of the root file system. This image can then create a bootable CD or USB drive.

Another method is to use a tool called “mkfs” to create a root file system on a blank hard drive. This method is generally more complicated and is not recommended for beginners.

Once you have created a root file system, you must install a bootloader. This is typically done using the “grub” bootloader. Once the bootloader is installed, you can boot into your new root file system.

If you use a computer with an existing operating system, you may need to modify your bootloader settings to boot into your new root file system. This is typically done by editing the “boot.ini” file.

Once your new root file system is up, you can begin installing software. Most Linux distributions come with a package manager that makes it easy to install the software.

How Do You Create A Root File?

You can create the root file system in several ways. One popular way is to use a tool such as mkfs. Another way is to use a disk partitioning program such as fdisk.

Once you have created the root file system, you need to mount it. The mount point is the location where the file system will be accessible.

What Is The Root Directory In Windows?

The root directory of a drive is the “highest” level directory of that drive. In other words, it is the first or topmost directory in the drive. All other directories on that drive are “subdirectories” of the root directory.

The term “root directory” can also refer to the directory that contains all the files and subdirectories for a particular software program. The Windows root directory is usually something like C:. In Linux, the root directory is /.

Configuring your system

Configure your system according to the main install guide. During startup, ZFS filesystems will be mounted without needing any entries in /etc/fstab. Comment out all entries in /etc/fstab except for partitions such as CD-ROMs, tmpfs, etc., if used.

If you created a swap volume earlier, add an appropriate entry to /etc/fstab.

Next, update the portage tree:

Arm construction steps are brief

The build process under arm is similar to the above, you can use an empty folder instead of switching back to the mirrorrootfs, Build Ubuntu rootfs in this folder, and then copy all files in this folder to the rootfs partition of SD card after the format has been formatted, or you can directly mount the rooyfs partition in SD card operating.

At present, general arm boards support booting from SD card. At the same time, there are two partitions in SD card. One Fat32 boot partition stores u-boot, and the other ext4 partition is the root file system. For the board started by nand flash, make the roofs according to the file system type and make a burn image, and burn nandflash.

Due to the openness of the arm board, hardware resources such as board peripherals and interfaces are not the same, and different manufacturers are very different. Unlike X86, hardware manufacturers use BIOS (UEFI) to shield the underlying differences, and the compatibility is strong (but now arm It has been improved. In the field of arm servers, the UEFI standard has been used like X86. The installation of win10 on the Raspberry Pi is an example of UEFI applications. In addition, the device tree also borrows from UFEI ACPI. For UEFI, you can access https://www.zhihu com/topic/19573354/top-answers understand).Therefore, after the rootfs construction is completed, the Linux kernel, u-boot, and device tree need to be transplanted.

1 download ubuntu-base

Take armhf as an example below.

3 Install qemu

-xpvf ubuntu-base-16.04.4-base-armhf.tar.gz -C /mnt

copyqemu-arm-staticGo to the directory just unzipped/mnt/usr/bin/：

Copy if it is arm64qemu-aarch64-static：

4 chroot operation

Everything else is the same2.3 Enter the chroot environment, The same. Update the source and install the required software.

update
net-tools vim bash-completion .

You can also execute a command directly through chroot, such as modifying the root password, where/mntIs our rootfs directory:

Install the software directly:

LC_ALLC LANGUAGEC LANGC /mnt packagename

5 Final

Install the kernel, save the kernel and device tree to the boot directory in rootfs, namely/mnt/boot/under. Except for nand flash.

It is consistent with common file system burning, making burning mirror, burning SD card or nandflash.

When you encounter the “no root file system is defined” error, your computer cannot find the operating system. This can be caused by various factors, including a corrupt or missing boot sector, a corrupt or missing partition table, or damage to the hard drive’s file system.

The above solutions should help you fix this error and keep your computer running. If you still have difficulty, you may need professional help.