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8
votes
3answers
3k views

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 ...
7
votes
2answers
46k views

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 ...
7
votes
1answer
58 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 ...
6
votes
2answers
1k views

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
votes
3answers
4k views

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 ...
6
votes
1answer
1k 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 ...
6
votes
2answers
1k views

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 ...
6
votes
4answers
1k views

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 ...
6
votes
3answers
5k views

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 ...
6
votes
1answer
424 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 ...
5
votes
3answers
875 views

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
votes
1answer
206 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
votes
2answers
134 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
votes
3answers
2k 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 ...
5
votes
1answer
912 views

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 ...
4
votes
1answer
2k views

Minimal Linux with kernel and BusyBox: /etc/inittab is ignored, only /init is executed

I managed to create a small and fully functional live Linux CD which contains only kernel (compiled with default options) and BusyBox (compiled with default options + static, all applets present, ...
4
votes
1answer
1k views

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 ...
4
votes
2answers
918 views

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 ...
4
votes
2answers
955 views

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 ...
3
votes
3answers
3k views

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
votes
3answers
1k views

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
votes
2answers
161 views

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 ...
3
votes
1answer
1k 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, ...
3
votes
1answer
1k 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
votes
3answers
181 views

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
votes
1answer
98 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
votes
1answer
119 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
votes
1answer
5k views

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
votes
1answer
811 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
votes
1answer
395 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
votes
1answer
165 views

vPrevent 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 ...
3
votes
0answers
162 views

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
votes
1answer
237 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 ...
2
votes
1answer
7k views

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 ...
2
votes
1answer
312 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 ...
2
votes
1answer
682 views

What is the meaning of the errors from my cpio command?

I have been using the following command on my system to create the .cpio archive to create an initramfs for my embedded target device sudo find . | cpio -H newc -oc > ~/initramfs.cpio This has ...
2
votes
2answers
616 views

Is it a bad idea to not have a swap partition on an embedded linux setup?

I have a small embedded linux kernel and file system created via buildroot that is installed onto a compact flash drive running on an x86 board. I am using an initramfs (due to power loss concerns) ...
2
votes
1answer
951 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 ...
2
votes
1answer
642 views

I want to understand Buildroot - the 3 compression config options (kernel, initramfs & rootfs)

I'm using buildroot to generate my images and for sure there is the option of compression with the help of different methods (LZO, LZMA, gzip, ...). So far i found these 3 compression options in ...
2
votes
1answer
933 views

Where is fsck startet for the root filesystem at boot?

I want to extend an existing Debian 6.0 system so that it is able to automatically fix a corrupt root file system by restoring a separate image. That process should start automatically instead of the ...
2
votes
2answers
782 views

dracut and separate /usr?

I would like to use systemd on my Gentoo box. Unfortunately, I have /usr on a separate partition and Gentoo puts libdbus into /usr/lib, leading to a segfault on boot, since systemd relies on dbus. ...
2
votes
1answer
5k views

RAMDISK incomplete write error kernel panic

I am building Linux Kernel 2.6.36.4 on a Dell Laptop which has Linux Kernel 2.6.35.11 running. BTW I got the source from kernel.org. The source had few syntax errors which I fixed in the process and ...
2
votes
1answer
469 views

Boot resolution change in initramfs on laptop monitor and HDMI monitor

I have Linux Mint 17 on my laptop. Also I have 22'' monitor connected to laptop using HDMI cable. My disk if fully encrypted with LUKS and LVM. On boot I get graphical prompt to enter password for ...
2
votes
1answer
1k 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) ...
2
votes
1answer
290 views

Fedora location of /usr/share/v86d/initramfs

I compiled and installed v86d, yet I can only locate one binary file in /sbin. There is supposed to be the initramfs file in /usr/share/v86d, but this directory does not exist. I don't think that the ...
2
votes
2answers
83 views

kernel compilation in ubuntu, reboot msg “gave up waiting for root device”

I was trying to compile Linux kernel from source file i.e. 3.19.3 kernel version I ran the following commands for compilation first I extracted tar -xvf linux-3.19.3.tar.xz changed to its ...
2
votes
0answers
269 views

Unable to boot with dracut and luks: '/dev/resume' : file exists

I am installing gentoo and have performed my first reboot after configuration and installation within my chroot environment. I am using LUKS and LVM to manage encryption of my drives. I am encrypting ...
2
votes
1answer
448 views

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 ...
2
votes
1answer
5k 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: ...
2
votes
0answers
381 views

Server won't boot, kernel panic - not syncing

After a reboot of a CentOS 6.2 server we are getting a kernel panic with the following error: Kernel panic - not syncing: Attempted to kill init! Panic occurred, switching back to text console ...