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Kexec
kexec (kernel execute), analogous to the Unix/Linux kernel call Exec (system call), exec, is a mechanism of the Linux kernel that allows booting of a new kernel (operating system), kernel from the currently running one. Details Essentially, kexec skips the bootloader stage and computer hardware, 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. B ... [...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 Computer network, 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 Data corruption, corruption while w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exec (system Call)
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 also 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 or some variant is available for many programming languages including compiled languages and some scripting languages. In 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 so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Mainline
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...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 x86-64 and AArch64 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. Ksplice is today offered on the two kernel flavors distributed with Oracle Linux: * UEK: the Unbreakable Enterprise Kernel * RHCK: the Red Hat Compatible Kernel , Ksplice is available for free on desktop Linux installations, with official support a ... [...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 ... [...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 ... [...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 kernel. LinuxBoot must run on top of hardware initialisation software in order to start. This can be the Pre- EFI Initialization (PEI) part of UEFI, coreboot, or U-Boot. It can boot Linux through the kexec syscall, but is also able to boot 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 EFI support of LinuxBoot is limited to a few servers: * Dell R630 * Open Compute Project Winterfell, Leopard, Monolake and Tioga Pas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Module
A loadable kernel module (LKM) is an executable library that extends the capabilities of a 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 Windows support loadable kernel modules but with 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, dynamically loadable kernel module in HP-UX, kernel-mode driver in Windows NT and downloadable kernel module (DKM) in VxWorks. They are also known as kernel loadable module (KLM), or simply as kernel module (KMOD). Advantages Without loadable kernel modules, an operating system would have to include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UEFI Secure Boot
Unified Extensible Firmware Interface (UEFI, as an acronym) is a Specification (technical standard), specification for the firmware Software architecture, architecture of a computing platform. When a computer booting, is powered on, the UEFI implementation is typically the first that runs, before starting the operating system. Examples include AMI Aptio, Phoenix Technologies, Phoenix SecureCore, TianoCore EDK II, and InsydeH2O. UEFI replaces the BIOS that was present in the boot ROM of all personal computers that are IBM PC compatible, although it can provide Backward compatibility, backwards compatibility with the BIOS using #CSM booting, CSM booting. Unlike its predecessor, BIOS, which is a de facto standard originally created by IBM as proprietary software, UEFI is an open standard maintained by an industry consortium. Like BIOS, most UEFI implementations are proprietary. Intel developed the original ''Extensible Firmware Interface'' (''EFI'') specification. The last Inte ... [...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 .e., uid=0 regardless of the name of that account; and in systems which implement a r 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 all mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
