The initial RAM disk (initrd) is an initial root file system that is mounted prior to when the real root file system is available. The initrd is bound to the kernel and loaded as part of the kernel boot procedure. … In the case of desktop or server Linux systems, the initrd is a transient file system.
What is initrd used for?
In computing (specifically as regards Linux computing), initrd (initial ramdisk) is a scheme for loading a temporary root file system into memory, which may be used as part of the Linux startup process.
What is initrd and initramfs in Linux?
@Amumu – initrd is a block device, and simply put, block devices are cached. initramfs is not a filesystem image, it is just a compressed cpio file; it is uncompressed into the tmpfs , just as when you decompress a zip file. –
How do I create an initrd image in Linux?
Creating initrd
initrd can be created with “mkinitrd” command. The location of initrd is /boot directory. The kernel version for which the initrd image is being created needs to be passed as an argument to the mkinitrd command. The current kernel version can be checked with uname command.
What is Ramfs in Linux?
Ramfs is a very simple FileSystem that exports Linux’s disk cacheing mechanisms (the page cache and dentry cache) as a dynamically resizable ram-based filesystem. Normally all files are cached in memory by Linux. … Basically, you’re mounting the disk cache as a filesystem.
What is the purpose of Systemd?
Its main aim is to unify service configuration and behavior across Linux distributions; systemd’s primary component is a “system and service manager”—an init system used to bootstrap user space and manage user processes.
What is bzImage in Linux?
The bzImage is the compressed kernel image created with command ‘make bzImage’ during kernel compile. It important to note that bzImage is not compressed with bzip2 !! The name bz in bzImage is misleading!! It stands for “Big Zimage”. The “b” in bzImage is “big”.
What is init process in Linux?
It is the first process executed by the kernel during the booting of a system. It is a daemon process which runs till the system is shutdown. That is why, it is the parent of all the processes. After determining default runlevel for the system, init starts all background processes required to run the system. …
What does Dracut do in Linux?
Dracut is a set of tools that provide enhanced functionality for automating the Linux boot process. The tool named dracut is used to create a Linux boot image (initramfs) by copying tools and files from an installed system and combining it with the Dracut framework, which is usually found in /usr/lib/dracut/modules.
How do you make initrd?
To create an initrd, begin by creating an empty file, using /dev/zero (a stream of zeroes) as input writing to the ramdisk. img file. The resulting file is 4MB in size (4000 1K blocks). Then use the mke2fs command to create an ext2 (second extended) file system using the empty file.
What is initrd IMG old?
If you stat /initrd.img.old you’ll likely find it’s a symbolic link (somewhat like shortcuts in windows; posix have multiple types of links) thus uses no disk space at all, it’s just a entry in the file system that points to your prior kernel. –