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Kexec
kexec, abbreviated from ''kernel execute'' and analogous to the Unix/Linux kernel call ''exec'', is a mechanism of the Linux kernel that allows booting of a new kernel from the currently running one. Essentially, kexec skips the bootloader stage and hardware initialization phase performed by the system firmware ( BIOS or UEFI), and directly loads the new kernel into main memory and starts executing it immediately. This avoids the long times associated with a full reboot, and can help systems to meet high-availability requirements by minimizing downtime. While feasible, implementing a mechanism such as kexec raises two major challenges: * Memory of the currently running kernel is overwritten by the new kernel, while the old one is still executing. * The new kernel will usually expect all hardware devices to be in a well defined state, in which they are after a system reboot because the system firmware resets them to a "sane" state. Bypassing a real reboot may leave devices i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kdump (Linux)
kdump is a feature of the Linux kernel that creates crash dumps in the event of a kernel crash. When triggered, kdump exports a memory image (also known as vmcore) that can be analyzed for the purposes of debugging and determining the cause of a crash. The dumped image of main memory, exported as an Executable and Linkable Format (ELF) object, can be accessed either directly through during the handling of a kernel crash, or it can be automatically saved to a locally accessible file system, to a raw device, or to a remote system accessible over network. Internals In the event of a kernel crash, kdump preserves system consistency by booting another Linux kernel, which is known as the ''dump-capture kernel'', and using it to export and save a memory dump. As a result, the system boots into a clean and reliable environment instead of relying on an already crashed kernel that may cause various issues, such as causing file system corruption while writing a memory dump file. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ksplice
Ksplice is an open-source extension of the Linux kernel that allows security patches to be applied to a running kernel without the need for reboots, avoiding downtimes and improving availability (a technique broadly referred to as dynamic software updating). Ksplice supports only the patches that do not make significant semantic changes to kernel's data structures. Ksplice has been implemented for Linux on the IA-32 and x86-64 architectures. It was developed by Ksplice, Inc. until 21 July 2011, when Oracle acquired Ksplice and then offered support for Oracle Linux. Support for Red Hat Enterprise Linux was dropped and turned into a free 30-day trial for RHEL customers as an incentive to migrate to Oracle Linux Premier Support. At the same time, use of the Oracle Unbreakable Enterprise Kernel (UEK) became a requirement for using Ksplice on production systems. , Ksplice is available for free on desktop Linux installations, with official support available for Fedora and Ubuntu Linux ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kpatch
kpatch is a feature of the Linux kernel that implements live patching of a running kernel, which allows kernel patches to be applied while the kernel is still running. By avoiding the need for rebooting the system with a new kernel that contains the desired patches, kpatch aims to maximize the system uptime and availability. At the same time, kpatch allows kernel-related security updates to be applied without deferring them to scheduled downtimes. Internally, kpatch allows entire functions in a running kernel to be replaced with their patched versions, doing that safely by stopping all running processes while the live patching is performed. kpatch is developed by Red Hat, with its source code licensed under the terms of the GNU General Public License version 2 (GPLv2). In May 2014, kpatch was submitted for inclusion into the Linux kernel mainline, and the minimalistic foundations for live patching were merged into the Linux kernel mainline in kernel version 4.0, which was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KGraft
kGraft is a feature of the Linux kernel that implements live patching of a running kernel, which allows kernel patches to be applied while the kernel is still running. By avoiding the need for rebooting the system with a new kernel that contains the desired patches, kGraft aims to maximize the system uptime and availability. At the same time, kGraft allows kernel-related security updates to be applied without deferring them to scheduled downtimes. Internally, kGraft allows entire functions in a running kernel to be replaced with their patched versions, doing that safely by selectively using original versions of functions to ensure per-process consistency while the live patching is performed. kGraft is developed by SUSE, with its source code licensed under the terms of versions two and three of the GNU General Public License (GPL). In April 2014, kGraft was submitted for inclusion into the Linux kernel mainline, and the minimalistic foundations for live patching were merged i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LinuxBoot
LinuxBoot is a free software project aimed at replacing most of the Driver Execution Environment (DXE) modules in Unified Extensible Firmware Interface (UEFI) firmware with the Linux, Linux kernel. LinuxBoot must run on top of hardware initialisation software in order to start. This can be the Pre-Extensible Firmware Interface, EFI Initialization (PEI) part of UEFI, coreboot, or Das U-Boot, U-Boot. It can boot Linux through the kexec syscall, but is also able to boot Microsoft Windows, Windows with a different method. History Originally, the project was started as NERF by Google. NERF was a stripped-down version of EFI which contains a Linux kernel and userland applications. This project has been split up into LinuxBoot (which contains the bootblock and kernel) and u-root, which contains the userland application. LinuxBoot became an official Linux Foundation project in 2018. Hardware support Currently, the Extensible Firmware Interface, EFI support of LinuxBoot is limited to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exec (computing)
In computing, exec is a functionality of an operating system that runs an executable file in the context of an already existing process, replacing the previous executable. This act is also referred to as an overlay. It is especially important in Unix-like systems, although it exists elsewhere. As no new process is created, the process identifier (PID) does not change, but the machine code, data, heap, and stack of the process are replaced by those of the new program. The ''exec'' call is available for many programming languages including compilable languages and some scripting languages. In OS command interpreters, the built-in command replaces the shell process with the specified program. Nomenclature Interfaces to ''exec'' and its implementations vary. Depending on programming language it may be accessible via one or more functions, and depending on operating system it may be represented with one or more actual system calls. For this reason ''exec'' is sometimes descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root User
In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of the account is not the determining factor; on Unix-like systems, for example, the user with a user identifier (UID) of zero is the superuser, regardless of the name of that account; and in systems which implement a role based security model, any user with the role of superuser (or its synonyms) can carry out all actions of the superuser account. The principle of least privilege recommends that most users and applications run under an ordinary account to perform their work, as a superuser account is capable of making unrestricted, potentially adverse, system-wide changes. Unix and Unix-like In Unix-like computer OSes (such as Linux), ''root'' is the conventional name of the user who has all rights or permissions (to all files and programs) in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel Relocation
Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learning * Kernelization, a technique for designing efficient algorithms ** Kernel, a routine that is executed in a vectorized loop, for example in general-purpose computing on graphics processing units *KERNAL, the Commodore operating system Mathematics Objects * Kernel (algebra), a general concept that includes: ** Kernel (linear algebra) or null space, a set of vectors mapped to the zero vector ** Kernel (category theory), a generalization of the kernel of a homomorphism ** Kernel (set theory), an equivalence relation: partition by image under a function ** Difference kernel, a binary equalizer: the kernel of the difference of two functions Functions * Kernel (geometry), the set of points within a polygon from which the whole polygon boundar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Module
In computing, a loadable kernel module (LKM) is an object file that contains code to extend the running kernel, or so-called ''base kernel'', of an operating system. LKMs are typically used to add support for new hardware (as device drivers) and/or filesystems, or for adding system calls. When the functionality provided by an LKM is no longer required, it can be unloaded in order to free memory and other resources. Most current Unix-like systems and Microsoft Windows support loadable kernel modules under different names, such as kernel loadable module (kld) in FreeBSD, kernel extension (kext) in macOS (although support for third-party modules is being dropped), kernel extension module in AIX, kernel-mode driver in Windows NT and downloadable kernel module (DKM) in VxWorks. They are also known as kernel loadable modules (or KLM), and simply as kernel modules (KMOD). Advantages Without loadable kernel modules, an operating system would have to include all possible anticipated fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UEFI Secure Boot
UEFI (Unified Extensible Firmware Interface) is a set of specifications written by the UEFI Forum. They define the architecture of the platform firmware used for booting and its interface for interaction with the operating system. Examples of firmware that implement these specifications are AMI Aptio, Phoenix SecureCore, TianoCore EDK II and InsydeH2O. UEFI replaces the BIOS which was present in the boot ROM of all personal computers that are IBM PC-compatible, although it can provide backwards compatibility with the BIOS using CSM booting. Intel developed the original ''Extensible Firmware Interface'' (''EFI'') specifications. Some of the EFI's practices and data formats mirror those of Microsoft Windows. In 2005, UEFI deprecated EFI 1.10 (the final release of EFI). UEFI is independent of platform and programming language, but C is used for the reference implementation TianoCore EDKII. History The original motivation for EFI came during early development of the first Int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Mainline
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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