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Initramfs
In Linux systems, initrd (''initial ramdisk'') is a scheme for loading a temporary root file system into memory, to be used as part of the Linux startup process. initrd and initramfs (from INITial RAM File System) refer to two different methods of achieving this. Both are commonly used to make preparations before the real root file system can be mounted. Rationale Many Linux distributions ship a single, generic Linux kernel image one which the distribution's developers create specifically to boot on a wide variety of hardware. The device drivers for this generic kernel image are included as loadable kernel modules because statically compiling many drivers into one kernel causes the kernel image to be much larger, perhaps too large to boot on computers with limited memory, or in some cases to cause boot-time crashes or other problems due to probing for nonexistent or conflicting hardware. This static-compiled kernel approach also leaves modules in kernel memory which are no longer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early User Space
The Linux booting process involves multiple stages and is in many ways similar to the BSD and other Unix-style boot processes, from which it derives. Although the Linux booting process depends very much on the computer architecture, those architectures share similar stages and software components, including system startup, bootloader execution, loading and startup of a Linux kernel image, and execution of various startup scripts and daemons. Those are grouped into 4 steps: system startup, bootloader stage, kernel stage, and init process. When a Linux system is powered up or reset, its processor will execute a specific firmware/program for system initialization, such as the power-on self-test, invoking the reset vector to start a program at a known address in flash/ROM (in embedded Linux devices), then load the bootloader into RAM for later execution. In IBM PC–compatible personal computers (PCs), this firmware/program is either a BIOS or a UEFI monitor, and is stored in the mai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casper (persistency)
In Linux systems, initrd (''initial ramdisk'') is a scheme for loading a temporary root file system into memory, to be used as part of the Linux startup process. initrd and initramfs (from INITial RAM File System) refer to two different methods of achieving this. Both are commonly used to make preparations before the real root file system can be mounted. Rationale Many Linux distributions ship a single, generic Linux kernel image one which the distribution's developers create specifically to boot on a wide variety of hardware. The device drivers for this generic kernel image are included as loadable kernel modules because statically compiling many drivers into one kernel causes the kernel image to be much larger, perhaps too large to boot on computers with limited memory, or in some cases to cause boot-time crashes or other problems due to probing for nonexistent or conflicting hardware. This static-compiled kernel approach also leaves modules in kernel memory which are no longer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cramfs
The compressed ROM/RAM file system (or cramfs) is a free ( GPL'ed) read-only Linux file system designed for simplicity and space-efficiency. It is mainly used in embedded and small-footprint systems. Unlike a compressed image of a conventional file system, a cramfs image can be used as it is, i.e. without first decompressing it. For this reason, some Linux distributions use cramfs for initrd images (Debian 3.1 in particular) and installation images (SUSE Linux in particular), where there are constraints on memory and image size. In 2013, Linux maintainers indicated that cramfs was made obsolete by squashfs, but the file system got rehabilitated in 2017 for use in low-memory devices where using squashfs may not be viable. Design Files on cramfs file systems are zlib-compressed one page at a time to allow random read access. The metadata is not compressed, but is expressed in a terse representation that is more space-efficient than conventional file systems. The file system i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debian
Debian () is a free and open-source software, free and open source Linux distribution, developed by the Debian Project, which was established by Ian Murdock in August 1993. Debian is one of the oldest operating systems based on the Linux kernel, and is the basis of List of Linux distributions#Debian-based, many other Linux distributions. As of September 2023, Debian is the second-oldest Linux distribution still in active development: only Slackware is older. The project is coordinated over the Internet by a team of volunteers guided by the List of Debian project leaders, Debian Project Leader and three foundational documents: the Debian Social Contract, the Debian Constitution, and the Debian Free Software Guidelines. In general, Debian has been developed openly and distributed freely according to some of the principles of the GNU Project and Free Software. Because of this, the Free Software Foundation sponsored the project from November 1994 to November 1995. However, Debian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Device
In Unix-like operating systems, a device file, device node, or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions. Overview Device files usually provide simple interfaces to standard devices (such as printers and serial ports), but can also be used to access specific unique resources on those devices, such as disk partitions. Additionally, device files are useful for accessing system resources that have no connection with any actual device, such as data sinks and random number generators. There are two general kinds of device files in Unix-like operating systems, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethernet
Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET. The original 10BASE5 Ethernet uses a thick coaxial cable as a shared medium. This was largely superseded by 10BASE2, which used a thinner and more flexible cable that was both less expensive and easier to use. More modern Ethernet variants use Ethernet over twisted pair, twisted pair and fiber optic links in conjunction with Network switch, switches. Over the course of its history, Ethernet data transfer rates have been increased from the original to the lates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trivial File Transfer Protocol
The Trivial File Transfer Protocol (TFTP) is a simple Lockstep (computing), lockstep communication protocol for transmitting or receiving files in a client-server application. A primary use of TFTP is in the early stages of nodes booting on a local area network when the operating system or firmware images are stored on a file server. TFTP was first standardized in 1981 and updated in . Overview Due to its simple design, TFTP can be easily implemented by code with a small memory footprint. It is, therefore, the protocol of choice for the initial stages of any network booting strategy like Bootstrap Protocol, BOOTP, Preboot Execution Environment, PXE, Boot Service Discovery Protocol, BSDP, etc., when targeting from highly resourced computers to very low resourced Single-board computers (SBC) and System-on-a-chip, System on a Chip (SoC). It is also used to transfer firmware images and configuration files to network appliances like Router (computing), routers, Firewall (computing) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Allocation Table
File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on Hard disk drive, hard disks and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in versions: #FAT12, FAT12, #FAT16, FAT16, #FAT32, FAT32, and exFAT. FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP. Nevertheless, FAT continues to be commonly used on relatively small capacity solid-state storage technologies such as SD card, MultiMediaCard (MMC) and eMMC because of its compatibility and ease of implementation. Uses Historical FAT was used on hard disk drive, hard disks throughout the DOS and Windows 9x eras. Microsoft introduced NTFS with the Windows NT platform in 1993, but FAT remained the standard for the home use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ext2
ext2, or second extended file system, is a file system for the Linux kernel (operating system), kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same principles as the Berkeley Fast File System from Berkeley Software Distribution, BSD, it was the first commercial-grade filesystem for Linux. The canonical implementation of ext2 is the "ext2fs" filesystem driver in the Linux kernel. Other implementations (of varying quality and completeness) exist in GNU Hurd, MINIX 3, some BSD kernels, in MiNT, Haiku (operating system), Haiku and as third-party Microsoft Windows and macOS (via Filesystem_in_Userspace, FUSE) drivers. This driver was deprecated in Linux version 6.9 in favor of the ext4 driver, as the ext4 driver works with ext2 filesystems. ext2 was the default filesystem in several Linux distributions, including Debian and Red Hat Linux, until supplanted by ext3, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Disc
An optical disc is a flat, usuallyNon-circular optical discs exist for fashion purposes; see shaped compact disc. disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side. Optical discs can store analog information (e.g. LaserDisc), digital information (e.g. DVD), or store on the same disc (e.g. CD Video). Their main uses are the distribution of media and data, and long-term archival. Design and technology The encoding material sits atop a thicker substrate (usually polycarbonate) that makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the entire disc surface and extending from the innermost track to the outermost track ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
El Torito (CD-ROM Standard)
ISO 9660 (also known as ECMA-119) is a file system for optical disc media. The file system is an international standard available from the International Organization for Standardization (ISO). Since the specification is publicly available, implementations have been written for many operating systems. ISO 9660 traces its roots to the ''High Sierra Format'', which arranged file information in a dense, sequential layout to minimize nonsequential access by using a hierarchical (eight levels of directories deep) tree file system arrangement, similar to Unix file systems and FAT. To facilitate cross platform compatibility, it defined a minimal set of common file attributes (directory or ordinary file and time of recording) and name attributes (name, extension, and version), and used a separate system use area where future optional extensions for each file may be specified. High Sierra was adopted in December 1986 (with changes) as an international standard by Ecma International as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
