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7
votes
3answers
2k 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 ...
6
votes
3answers
3k 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
2answers
974 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
1answer
40 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 ...
5
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 ...
5
votes
3answers
550 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
3answers
2k 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 ...
5
votes
1answer
154 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
4answers
313 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 ...
5
votes
3answers
1k 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
373 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 ...
4
votes
1answer
762 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 ...
4
votes
2answers
12k 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 ...
4
votes
2answers
308 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
1answer
608 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 ...
3
votes
3answers
2k 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
894 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
1answer
562 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
2answers
121 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 ...
3
votes
1answer
256 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
533 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 ...
3
votes
1answer
45 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
1k 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
336 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
292 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
195 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, ...
3
votes
0answers
103 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
170 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
2answers
633 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 ...
2
votes
1answer
4k 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
205 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
380 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
446 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
735 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
149 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 ...
2
votes
2answers
720 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
180 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
261 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
0answers
190 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 ...
2
votes
0answers
243 views

Why do I need to specify two init images - initrd and boot - inside KVM to boot to bash?

My machine is running inside a KVM virtual machine (Parallels Desktop v8), having a BIOS (not UEFI), having one SATA drive connected, one GPT partition on that disk, the partition is ext4 formatted, ...
2
votes
2answers
734 views

busybox initramfs loop mount

I'm trying to loop mount my root filesystem (a loop file) within a busybox initramfs. I try to run the command: mount /rootfs.raw /root ... which works on my Ubuntu laptop, however, I simply get ...
2
votes
0answers
317 views

Booting over the LAN using uboot

I am trying to boot my beaglebone over the LAN. I am able to download the Kernel uImage from the TFTP server. Here is what I did - U-Boot SPL 2011.09-00053-gb423c52 (Aug 10 2012 - 11:26:55) Texas ...
1
vote
2answers
87 views

Understanding a simple configuration file for initramfs

I am new to file system. Can somebody explain me what is happening in the following? # This is a very simple, default initramfs dir /dev 0755 0 0 nod /dev/console 0600 0 0 c 5 1 nod ...
1
vote
1answer
211 views

Initrd : Were can I found the code for real-root-dev

I'm trying to customize my initrd on kernel 2.4. At some point, inside the file linuxrc, I have the opportunity to set my root device setting the /proc/sys/kernel/real-root-dev variable The example ...
1
vote
1answer
309 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 ...
1
vote
1answer
112 views

Initramfs post-update hook

I need an initramfs hook to call a script after an initramfs has been generated. The Debian Linux Kernel Handbook mentions /etc/initramfs/post-update.d/: Packages for boot loaders that need to be ...
1
vote
1answer
878 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 ...
1
vote
1answer
4k 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 ...
1
vote
1answer
657 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) ...
1
vote
1answer
265 views

How to regenerate initramfs so it can include bcache module?

Eventually I have converted root-fs into bcache (with the help of blocks). I skipped the step update-initramfs -u -k all because I've been using bcache on other partitions for some time, and I've ...