The "initial RAM file system" is the successor of initrd. It is a root filesystem that is embedded into the kernel and loaded early in the boot process.

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How to fix boot into initramfs prompt and “mount: can't read '/etc/fstab': No such file or directory” and “No init found”?

Installing a new system using a GPT partitioned disk dedicated to a single partition, ext4 formatted, extlinux (version 4.05) as bootloader, Ubuntu Core version 13.10 amd64 as rootfs, and Ubuntu linux-...
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3answers
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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 ...
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Why does initramfs mount the root filesystem read-only

What is the reason for the root filesystem being mounted ro in the initramfs (and in initrd). For example the Gentoo initramfs guide mounts the root filesystem with: mount -o ro /dev/sda1 /mnt/root ...
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3answers
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Does initramfs use /etc/fstab?

The way I understand it, initramfs is responsible for loading the "real" root filesystem. Now, there are two places where we define that root. First we put an entry in /etc/fstab. Second, we put the ...
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4answers
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Why do I need initramfs ?

I found that if I choose jffs or sd as file system(and not initramfs),the kernel size is very small (1.4 MB as compared to with initramfs-3.4MB). It shows that initramfs takes concidreably large space....
8
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492 views

GRUB confuses kernels/initramfs of Ubuntu and Arch Linux installation

I have a machine that used to dual-boot Ubuntu (16.04 currently) and Windows 7, with Ubuntu's GRUB as boot loader. Now I just added Arch Linux as third OS, following the official installation ...
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2answers
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Why use cpio for initramfs?

I am making my own initramfs following the Gentoo wiki. Instead of the familiar tar and gzip, the page is telling me to use cpio and gzip. Wikipedia says that cpio is used by the 2.6 kernel's ...
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1answer
104 views

How do I know what decompression algorithms are compiled-in into the linux kernel?

If /proc/config.gz is unavailable, how do I know what decompression algorithms the running kernel is capable of using on a compressed cpio initramfs? Is the gzip algorithm always available, even when ...
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How is a Linux kernel capable of accessing its assigned initramfs/initrd?

I'm trying to understand the boot process of a machine as a whole from the time you hit the power button. There's this one piece from bootloader to initramfs stage I don't quite understand among some ...
6
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1answer
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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 ...
6
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1answer
480 views

Does the kernel delete entries in /dev on an initramfs?

I have a fully custom, minimal, embedded Linux (vanilla, 3.3.8, i486, Vortex86dx) system that boots from an initramfs image. No standard distribution scripts are used, just a single rcS file that does ...
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1answer
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Adding dropbear to initramfs with dracut on Fedora

I'm trying to add dropbear to my initramfs so I can unlock the encrypted disk through a remote SSH session (as described here). I'm running Fedora 16 which apparently uses dracut to generate the ...
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3answers
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How to generate initramfs image with busybox links?

Having been directed to initramfs by an answer to my earlier question (thanks!), I've been working on getting initramfs working. I can now boot the kernel and drop to a shell prompt, where I can ...
5
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3answers
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Is making /etc directory read only a bad idea?

I have an embedded system setup built using buildroot and using initramfs. It runs on compact flash device where I have created separate ext3 partitions to mount /etc/ and /var directories as well as ...
5
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1answer
292 views

can initramfs be paged out to swap disk?

I am using initramfs to boot Centos via PXE. The initramfs used memory is listed within the "cached" value in /proc/meminfo or via free. Since I need to calculate performance data, I need to know ...
5
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2answers
140 views

Where to install local software that runs before /usr is available?

I'm writing a local program to be called by a udev IMPORT{program} rule. Normally, I'd install local software in /usr/local, but these udev rules are run when block devices appear. So they're running ...
5
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1answer
4k views

When would you use pivot_root over switch_root?

I'm wanting to understand the Linux init process better in order to netboot a system over ceph rather than nfs. In the process I've come across two forms of switching root. One called switch_root, ...
5
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Adding a file to /etc of initramfs in Debian Wheezy

I have added the file /etc/initramfs-tools/etc/motd so that it would be available in /etc of the initramfs environment. However, it does not turn up. This is my second try where I gave the file all ...
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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
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1answer
280 views

Difference in execution of init with embedded vs. external initramfs?

I'm building a very minimal linux system that just consists of the kernel (v4.1-rc5) and an initramfs populated with busybox (v1.23.2). It works fine for the most part, but I observe a difference in ...
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1answer
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Prevent Debian from auto-assembling RAID at boot

I set up a Debian wheezy (7.6), installed openmediavault, and created a software raid 5 with that. It is listed at /dev/md127. Now I want to move that to a virtual XEN VM. To do so, I have to stop ...
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How do I build a read-only Linux system that only writes to the RAM?

This is my current partition structure: Filesystem 1K-blocks Used Available Use% Mounted on tmpfs 127428 0 127428 0% /lib/init/rw udev ...
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1answer
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Excluding kernel modules through /etc/modprobe.d/blacklist.conf does not work

I don't want to load the kernel module nouveau on my debian box at startup, so I put the following in /etc/modprobe.d/blacklist.conf: blacklist ttm blacklist drm blacklist nouveau I even did a ...
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2answers
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Live Distros: UBCD boot Deft, Caine, and Tails from Custom Menu

I'm building my own UBCD and I'm using dual layer to fit 7.5Gigs Useful resources for UBCD customization: The SYSLINUX Project UBCD Customize Casper Man Page Live Boot Man Page Here's my ...
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Unlock LUKS encrypted Debian root with key file on boot partition

I'm trying to decrypt the Debian root with a key file stored in the boot partition (decrypted partition). This will break the security, but it doesn't matter now. I have to conclude this successfully ...
4
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1answer
11k views

Arch Linux in Qemu : Failed to access perfctr msr error

I got the Arch Linux (march build) iso file through bittorrent lately. I tried to run it in VM, but it only gets up to the main screen (The screen where you select what you want to do) shown below: ...
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Given vmlinuz and initrd.gz, how do I find out, where the kernel is going to load / (root) file system from?

I'm trying various ways of Linux installation (from iso, flash, iso on flash, kernel on flash, root FS in iso-file on flash...) and want to understand what's going on. My question is: is it possible, ...
3
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3answers
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after replacing motherboard, Debian gets blank screen while booting

I have Debian installed on one computer. I just replaced its motherboard and CPU. And graphics card, because I use onboard one. I kept my old hard disk. Now machine boots well, grub starts well, ...
3
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1answer
570 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
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30 views

How to create ASCII cpio archive (SVR4 with no CRC)?

I have a file in /boot/initramfs.gz extract it using tar -xzvf initramfs.gz -C ./ I got a file initramfs. └──╼ $ file initramfs initramfs: ASCII cpio archive (SVR4 with no CRC) It can be open ...
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Extracting concatenated cpio archives

initramfs archives on Linux can consist of a series of concatenated, gzipped cpio files. Given such an archive, how can one extract all the embedded archives, as opposed to only the first one? The ...
3
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2answers
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Can I make low-level changes on a root fs mounted RO?

Related to this question: having a root file system that had to be mounted read-only (say it's completely broken), can I reformat the partition or dd a older backup image on top of it (and then reboot)...
3
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1answer
989 views

Compiled a Kernel (2.6.39-rc1), where is the corresponding initramfs?

as I've already wrote in the topic, I compiled a new Kernel with make defconfig, the bzImage is where it there, so is vmlinux.bin. I've installed modules with make modules_install. Now, what is the ...
3
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1answer
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After installing a new Kernel in Ubuntu 14.04, rebooting takes me to busybox initramfs. How do I mount a filesystem after that?

I have a virtual machine with Ubuntu 14.04 in it. I recently built and installed linux-3.14.5 kernel on it, and tried to boot into it, but it drops me to BusyBox v1.21.1 built-in shell. Here's what I ...
3
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1answer
2k views

How to set laptop screen brightness just after boot with full disk encryption

my girlfriend bought Lenovo Essential G500 i5-3230 and I installed Linux Mint 16 on it with full disk encryption. It is standard installation with encryption using dmcrypt and LUKS. But there is a ...
3
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1answer
221 views

On Gentoo, ZFS stops working after 0.6.5 update

I just updated my Gentoo system, updating my world, including ZFS. Everything but the kernel. I figured I'd do a reboot first, then build a new kernel. Currently, it's running on kernel 3.17.8-gentoo-...
3
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3answers
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Building a Read-Only Linux System With a Writable Layer in RAM

I have a requirement to boot RHEL 6.6/7.0 into read-only mode with a writable layer only in RAM. I believe this is similar to how live CDs work, in that the file system is read-only, but certain parts ...
3
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1answer
2k views

How to mark “not fully installed” apt-get package as “successfully installed”

I have installed Debian 7.4 on my Iomega ix2-200 NAS, following this blog. The ix2-200 is running an ARM Marvel CPU and has a 128 MB NAND flash memory. The flash contains an initramfs image (uInitrd) ...
3
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1answer
127 views

Two compiles of the same kernel version: one boots, one unable to find root device

I have two compiles of the same kernel version (4.0.5+gentoo patches). One boots, correctly, but lacks several kernel CONFIG flags. Adding those flags and running make all && make install ...
3
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1answer
281 views

disable dhcp in initramfs

In Debian, how can I tell initramfs not to request an IP address via DHCP? I'm using initramfs-tools. I'd be okay with assigning a static IP address for the initramfs, but I can't find how to set ...
3
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1answer
225 views

eCryptfs key in kernel image or initramfs

I have an embedded Linux system with unencrypted kernel image and initramfs in NAND flash. My RootFS is in SD card. I want to encrypted some files on SD Card as my SD card is easily accessible ...
3
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2answers
1k views

How can I install Linux on a UEFI system with Secure boot?

My motherboard is a Gigabyte 990XA-UD3 (CPU 1), it's a UEFI -Dual boot, and when I try installing Linux Mint 16 Cinnamon or Ubuntu 13.10 it always bring this error (initramfs) Unable to find a medium ...
3
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1answer
525 views

Using ramfs on embedded system

I am required to write some software to run on Linux installed on an x86 based embedded setup that has a 8GB compact flash drive for data storage. The critical requirements are logging measurement ...
3
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1answer
227 views

How to debug systemd “init” freeze during boot?

I'm trying to get my own init script running on some ARM hardware and Debian Jessie with systemd. The overall boot concept and init script is almost identical to a x86 variant, which works fine. For ...
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How do I add modules, binaries or scripts to initramfs in RHEL distributions?

I have an initramfs script I developed for Debian distributions that required some extra binaries to be loaded into the image. I'm now trying to port this to RHEL distributions and I'm struggling. To ...
3
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2answers
327 views

Debian Jessie initramfs-tools strange behavior

My current system is: $ lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 8.1 (jessie) Release: 8.1 Codename: jessie with kernel: $ uname -a ...
3
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How do I bypass entering exit manually at the initramfs prompt?

I installed lubuntu onto my desktop PC and it does not have any other OS on it. Everytime the system boots up, I get to the initramfs prompt. It does not show any errors. If I enter exit, the system ...
3
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1answer
305 views

Relative path to anything not working (while running from initramfs)

I'm working in an embedded Linux system trying to get it booting its root file system in ram using initramfs. The system comes up for the most part but then has trouble in the init scripts. I've ...
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Changing a root file system from initramfs to JFFS2

I am running Linux on an ARM based development board from flash memory. The rootfs is initramfs. I chose this in the configuration utility under "file system". Then I realized that I need ...
3
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1answer
348 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 ...