Questions tagged [initrd]

initrd is a method for loading a temporary file system into memory, during the process of booting the Linux kernel.

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40
votes
6answers
15k views

Why is it that my initrd only has one directory, namely, 'kernel'?

I'm using debian live-build to work on a bootable system. By the end of the process i get the typical files used to boot a live system: a squashfs file, some GRUB modules and config files, and an ...
18
votes
1answer
27k views

What is the equivalent of mkinitcpio.conf on debian?

I want to review that the hooks used to build the initrd.img are correct in my debian but I fail to find the /etc/mkinitcpio.conf file like the one in Archlinux, what is the equivalent of this file in ...
16
votes
3answers
35k views

How does Linux load the 'initrd' image?

I've been trying to understand the booting process, but there's just one thing that is going over my head.. As soon as the Linux kernel has been booted and the root file system (/) mounted, programs ...
15
votes
3answers
8k views

Is the entire kernel loaded into memory on boot?

I read through this popular IBM doc (I see it referred quite often on the web) explaining the function of the initial RAM disk. I hit a wall in conceptualizing how this works though. In the doc it ...
13
votes
5answers
12k views

Is it possible to put root in LVM without using initrd?

I have just set up a Gentoo base system (which means I can boot and log in and do stuff with it now). My root partition is in an LVM2 virtual group (with a separated /boot partition). In order to boot ...
12
votes
1answer
5k views

Why is my initial ramdisk so big?

I'm running Ubuntu 11.10, which came with kernel version 3.0.0-14. I downloaded and built a kernel from the 3.1.0 branch. After installing the new kernel, I see that my /boot/initrd.img-3.1.0 file is ...
11
votes
3answers
21k views

Linux kernel is not finding the initrd correctly

I had compiled a linux kernel and I wanted to debug it in QEMU. I created a file to boot from by doing the commands $ qemu-img create -f raw disk.img 200M $ mkfs.ext2 -F disk.img # mkdir /mnt/rootfs ...
10
votes
1answer
8k views

How can I force a Ubuntu kernel to fail mounting / and drop into the initramfs rescue shell?

I am trying to customize the initramfs rescue environment and would like to force the kernel to fail mounting / and drop into the (initramfs) rescue shell, as opposed to single user mode. How can I ...
10
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2answers
12k views

vmlinuz and initrd not found after building the kernel?

After configuring and building the kernel using make, why don't I have vmlinuz-<version>-default.img and initrd-<version>.img, but only got a huge vmlinux binary (~150MB)?
10
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1answer
4k views

Is Ramdisk and initrd the same?

While reading through the kernel documentation on ramdisk in ramfs-rootfs-initramfs.txt i was having a doubt like the ramdisk explained there is same as the initrd features described in the post at ...
9
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2answers
13k views

How to populate /dev directory when building my own initrd?

I am trying to learn stuff about initrd. I have followed this tutorial to build my own initrd from scratch, and I installed busybox on it. Then I made an .iso from it with isolinux, so I could test it ...
8
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2answers
31k views

Ubuntu: How do the md devices get assembled at bootup?

How do the md devices get assembled at bootup in Ubuntu? Is /etc/mdadm/mdadm.conf truly the relevant factor here? My mdadm.conf is sound and I checked that while I was in the rescue CD environment. ...
7
votes
2answers
8k views

Add Apache to Ubuntu's startup

I'm currently learning the Linux environment, and decided to manually install the Apache server. For educational purposes, I've compiled it into: /server/apache The http.conf location is configured ...
7
votes
2answers
1k views

Repack the filesystem image from vmlinux.bin (embedded initramfs) without rebuilding?

In How do I extract the filesystem image from vmlinux.bin? and https://wiki.gentoo.org/wiki/Custom_Initramfs#Salvaging methods are presented for getting and unpacking an embedded initramfs/initrd ...
6
votes
1answer
4k views

Booting without initrd

Is it possible to boot linux without a initrd.img ? I am planning to add default drivers as a part-of-kernel itself and avoid initrd completely. What are the modules that should be made part-of-the-...
6
votes
2answers
8k views

How to make a minimal bootable linux (only with terminal) from kernel source code? [duplicate]

I want to make a very minimal linux os which only have a terminal interface and basic commands/applications (busybox is my choice for commands/apps). I don't want the installation option on my os. I ...
6
votes
1answer
846 views

How to combine linux kernel and initrd without compiling?

I know that it's possible to extract from a linux kernel the embedded initramfs cpio. I want to know if the reverse operation is possible; i.e., given both a compiled kernel and initramfs archive, how ...
6
votes
2answers
3k views

What does mkinitrd change when it adds kernel modules to the initrd?

When creating an initrd using mkinitrd (CentOS 5.5), the kernel modules it adds to the initrd get modified in the process. For example, the initrd's /lib/sata_via.ko is not binary identical to /lib/...
5
votes
4answers
12k views

Unpack, modify and pack initrd as a user

I've got a problem with rebuilding the initrd image as a user. Firstly, when I try to "unpack" the original initrd image: cpio -idm < initrd-base cpio: dev/tty8: Cannot mknod: Operation not ...
5
votes
3answers
4k views

Why do we need initramfs and initrd

For example we have exotic file system on the disk and in order to load system we need mount root filesystem. But we cannot because there is no suitable driver exists in kernel image. Let me ...
5
votes
3answers
10k views

Can the initramfs image use a compression format other than gzip?

Can the initramfs image be compressed by a method other than gzip, such as lzma?
5
votes
2answers
6k views

Kernel freezes on loading ramdisk. How to find out what's wrong?

I'm using an Ubuntu Server (13.04) Minimal installation (with the Xubuntu Metapackage as a desktop environment, if that matters) on x86_64 on my Samsung notebook. I'm currently forced to use the no-...
5
votes
3answers
4k views

Does /init (or /linuxrc) script creates temporary device nodes in /dev?

Considering that GRUB executes following lines: kernel /vmlinuz root=/dev/sda1 ro initrd /initrd On boot, how does the Linux kernel finds out about /dev/sda1 device node? I know that initrd/...
5
votes
1answer
2k views

Adding files to initrd makes linux not be able to read it

I'm using clonezilla-1.2.12 and need to add the Broadcom firmware to the initrd so it can netboot. (clonezilla is debian-based and debian no longer includes the firmware blobs as they're non-free. ...
5
votes
1answer
1k views

How do I load initrd into memory to be passed to kernel when using kexec?

As the MIPS port of kexec doesn't support the --initrd param, I'm looking for workarounds to imitate the feature. According to Linux/MIPS wiki, MIPS kernels support rd_start and rd_size kernel command ...
5
votes
1answer
1k views

Will a “customized” initrd survive a kernel update via yum?

I have a CentOS 5.5 installation with the stock CentOS 5.5 kernel. I have modified the init script in the initrd, commenting out some unneeded modules, lowering the interval time of the "stabilized" ...
4
votes
2answers
625 views

/boot/vmlinuz file is not presemt

I am using debian and when I was just checking my filesystem there was no vmlinuz file and after a bit of googling many user with no vmlinuz were having trouble to boot but my computer is booting well....
4
votes
1answer
1k views

Did the pivot_root() documentation anticipate the feature of mount namespaces?

pivot_root() moves the root filesystem of the calling process to the directory put_old and makes new_root the new root filesystem of the calling process. The typical use of pivot_root(...
4
votes
1answer
2k views

Measurement of free ram through /proc/meminfo with ramdisk (initrd)

I am booting a disk image via PXE, it is a full system on an initrd ramdisk. I would like to measure the actual free memory of the system (not including buffers and file system caching). I was told ...
4
votes
1answer
1k views

Are there any canned solutions for running sshd in the initrd?

This is mostly aimed at Debian/Ubuntu, but I feel savvy enough on a variety of distros to be able to adapt the solution for one distro to another. Here's my scenario. There are a few situations when ...
3
votes
1answer
869 views

When would an initrd be necessary?

I've read that I can boot the kernel without initrd, and I've also read that additional modules are loaded during the initrd stage -- as I understand it, for necessary drivers that weren't included in ...
3
votes
1answer
917 views

My initrd has only one directory, after decompressing, namely 'kernel'

The file shows 56 blocks as the size. I am using the system Ubuntu 16.04 and I need a solution that does not require me to update the kernel.
3
votes
2answers
649 views

Why kernel cannot do the initrd/initramfs job itself? [closed]

Currently I am learning about linux booting process.Here i noticed that the initrd will create temporary root file system that includes drivers(LVM, NFS, etc) which are required by kernel.After that ...
3
votes
1answer
4k views

Patching the kernel to allow booting without initrd

The first answer of 'Why does Linux use an Initial Ram Disk at boot?' states that the initrd/initial ram filesystem is used to provide drivers to mount the real root filesystem. It also says that it ...
3
votes
1answer
3k views

Creating new initrd without installing kernel

How can i create initrd image for a new(experimental) kernel without actually installing it. (Existing tools to create initrd based on config and details from installed kernel.) Say i compile a new ...
3
votes
2answers
1k views

Is there a way to get Linux to treat an initramfs as the final root filesystem?

I want to boot a system with an initramfs that's the actual final filesystem, not a temporary initramfs for loading drivers. Unfortunately, Linux imposes different (and in my case, undesirable) ...
3
votes
1answer
658 views

Mount /etc from disc into squashfs

I've created a gentoo-live system which should be booted from a CF-card. The whole file-system is in a squashfs. I've created a custom initrd which first mounts the CF-card and from there the squashed ...
3
votes
1answer
868 views

Getting keyboard to work in debian 6.0 in order to unlock root partition

I just installed Debian 6.0, encrypted / and now I'm trying to boot. When GRUB comes up, I select Debian, it loads the initrd and asks for the root password, however I can't enter anything, because ...
3
votes
1answer
59 views

A Small GUI Linux System with UEFI completely running on RAMDisk

I am developing a POS System and I am planning to use Linux. My requirements are as follows UEFI Support. (Running on x86 and x86_64) No Storage Drive so completely running on RAM and persistence ...
3
votes
0answers
4k views

Ubuntu 18.04 LUKS boot problems

Problem description I am trying to achieve dualboot of Windows 10 (pre-installed) and Ubuntu 18.04 on a new laptop. This is not very difficult, however it appears to get much more complex if you also ...
3
votes
1answer
2k views

How can I replace root / filesystem with another filesystem?

When the Linux kernel starts up, it uses initrd as the root / filesystem, then replaces that with a filesystem partition in fstab. Based on a test in an early init script, I want to replace that root ...
3
votes
1answer
526 views

initrd or ramfs for SLES as /

I would like to boot a SLES and run it out of a ramdisk. I would like to setup machines so that they start PXE boot and as part of the PXE boot process they pull across an image that is the root ...
3
votes
1answer
579 views

Create Logical Volume Snapshot at boot and before mount

I'm using Kubuntu 11.10 and before I upgrade to 12.04, I want to make snapshots of my filesystems. Coming to think of that, I realized that it can be very useful to create snapshots of logical volumes ...
2
votes
2answers
3k views

Grub: boot with USB key, then continue booting from SD card?

I have an old laptop that has a built-in SD card reader, only it's not available at boot. I can however grub boot linux (Debian) from a small 8GB USB key (USB 2.0), but it's very slow. The SD card is ...
2
votes
2answers
1k views

Why don't we include File System drivers in the kernel itself instead of using Initrd/Initramfs

The Linux kernel contains very minimal code that is necessary to boot on a majority of devices but I don't get the point of having Initrd/Initramfs.As far as I've understood Initrd/Initramfs job is to ...
2
votes
2answers
3k views

How to open the clonezilla initrd.img?

I am not understand why I get the error about initrd.img ( this initrd.img is the original file from clonezilla ISO file cp initrd.img /tmp zcat /tmp/initrd.img | cpio -idm zcat: initrd.img: not in ...
2
votes
1answer
957 views

How do i run a process in a specific directory?

In an init.d file i wrote the below. Now i need to make the bin run in a specific directory. How do i tell it which directory to use? mono --debug /path/bin &
2
votes
3answers
2k views

Avoid pause during dm-raid initialization

On my CentOS 5 workstation I get a few seconds wait after dm-raid45 has been loaded ("Initializing Driver" or something like that). This seems to be part of the initrd. After that the system boots up....
2
votes
1answer
2k views

switch_root gives Invalid argument

My goal is to unmount the root disk so I can format it. To do this, I want to switch root from the hard disk to some other root. I have chosen to use the files from the initramfs (which contains a ...
2
votes
1answer
741 views

Linux initrd environment setup - Failed to execute /init

I'm looking for help in getting a basic initrd environment up and running. My goal is to enhance my knowledge on how to create a basic Linux environment. Ideally, I would like to move into Embedded ...