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6
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
871 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 ...
5
votes
2answers
788 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
400 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
119 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
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
336 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
487 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
3answers
572 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 ...
3
votes
2answers
118 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
4answers
114 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 ...
3
votes
1answer
213 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
222 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
0answers
39 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
120 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
489 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 ...
2
votes
3answers
706 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, ...
2
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, ...
2
votes
1answer
3k 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
158 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
204 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
1answer
575 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
1answer
101 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 ...
2
votes
2answers
139 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
666 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
2answers
213 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 ...
2
votes
1answer
243 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
56 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
0answers
70 views

How can I install linux on a system with UEFI and Security boot system?

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 ...
2
votes
2answers
355 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
2answers
461 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
0answers
253 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
343 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) ...
1
vote
1answer
159 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
2answers
29 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
69 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
815 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
3k 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
35 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
55 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 ...
1
vote
1answer
91 views

Using qemu to boot OpenSUSE (or any other OS) with custom kernel

I want to run OpenSUSE as guest with a custom kernel image which is on my host machine. I'm trying: $ qemu-system-x86_64 -hda opensuse.img -m 512 -kernel \ ...
1
vote
1answer
840 views

How to make an entry of Slackware into grub2

I want to manually add the Slackware entry into the GRUB2 configuration file /boot/grub/grub.cfg. But the problem is that there is no initrd or initramfs present in /boot directory of Slackware. I saw ...
1
vote
1answer
10 views

Correct location of initramfs.cpio file when compiling kernel

I am following this article and generated an initramfs.cpio file. Now the tutorial mentiones that I have to put this file in build directory: Finally, you have to rebuild the kernel again: # 0. ...
1
vote
1answer
16 views

Difference between initramfs.cpio and rootfs.cpio

What are the differnces between the two? Can I just use initramfs.cpio or do I need to use both? Actually my rootfs.cpio file is 7 Mb and initramfs.cpio is just 0.5mb, so I was thinking if I can use ...
1
vote
0answers
22 views

Replacing default initramfs with my own

I followed this article to develop my own sample intramfs.cpio Now I have to put this in my kernel and compile. The procedure that I follw for petlinux is that I first run petalinux-config (and ...
1
vote
0answers
21 views

Kiwi produces huge initramfs

I'm using Kiwi to build a boot CD based on OpenSUSE 13.1. I want the disk ISO image to be as tiny as possible. I managed to get the read-only filesystem down to only 100MB, but for reasons unknown, ...
1
vote
0answers
150 views

unionfs filesystem

I recently learned about unionfs and aufs and would like to put it to some real use. The scenario I have in mind is the following. Boot a machine with ubuntu on it which will serve as our base. Make ...
0
votes
1answer
51 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 ...
0
votes
1answer
244 views

What happens with /etc/fstab when using an initramfs?

I have a simple embedded setup as follows: x86 target, kernel and root file system built using buildroot. Syslinux is the bootloader configured to boot with an initramfs which points to a .cpio file ...