![]() ![]() ![]() For example, there is an 18.04.4 point release as of February 2020, which includes an updated 5.3.x kernel but is also considered LTS, exactly like the original GA 4.15 kernel in 18.04. Another option for customers is to use point releases. ![]() ![]() HWE kernel customers are recommended to upgrade to a newer LTS release that supports their hardware and/or software needs as soon as it is available. Customers who need the latest hardware support capability can install the latest HWE kernel such as the ones contained in interim releases, keeping in mind the shorter support lifespan associated with these kernels (9 months). Canonical also provides interim operating system releases with updated kernels every 6 months.įor customers and business partners that don't have specialised bleeding-edge workloads or latest hardware needs, the latest LTS release "-generic" kernel is the best option for them such as the 4.15 default kernel in Ubuntu 18.04 LTS. In practice, this is true only in the scope of the one thread, but I can't think of any situation where a compiler would even try to optimize accesses between threads. On multiprocessor systems, it was necessary to define current as an array-one element for each available CPU.Canonical provides long-term support (LTS) kernels for Ubuntu LTS releases. 2 Answers Sorted by: 15 Attribute const means that the returned pointer will remain the same for the duration of the program. Instead, it was forced to introduce a global static variable called current to identify the process descriptor of the running process. Linux 2.0 did not store the kernel stack and the process descriptor together. Replace 'x' for all versions bigger than the version 'x' of your current source tree, inorder, and you should be ok. For example, current->pid returns the process ID of the process currently running on the CPU.Īnother advantage of storing the process descriptor with the stack emerges on multiprocessor systems: the correct current process for each hardware processor can be derived just by checking the stack, as shown previously. To install by patching, get all the newer patch files, enter the top level directory of the kernel source (linux-6.x) and execute: xz -cd. But since they have generally heard the whole system called Linux as well, they often envisage a history. The current macro often appears in kernel code as a prefix to fields of the process descriptor. Programmers generally know that Linux is a kernel. for linux-image-4.18.0-2-amd64 the ABI is version 2. This may turn out to be a problem when little dynamic memory is available. The Linux kernel binary packages include an ABI version number, e.g. The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel. One drawback to the shared-storage approach is that, for efficiency reasons, the kernel stores the 8-KB memory area in two consecutive page frames with the first page frame aligned to a multiple of 213. This article documents the version history of the Linux kernel. When this occurs, Fedora updates to the new major version after a couple upstream. Movl $0xffffe000, %ecx andl %esp, %ecx movl %ecx, pĪfter executing these three instructions, p contains the process descriptor pointer of the process running on the CPU that executes the instruction. The Linux kernel releases new major versions (5.y releases) every few months. This is done by the current macro, which produces assembly language instructions like the following: In fact, since the memory area is 8 KB (213 bytes) long, all the kernel has to do is mask out the 13 least significant bits of esp to obtain the base address of the process descriptor. The close association between the process descriptor and the Kernel Mode stack just described offers a key benefit in terms of efficiency: the kernel can easily obtain the process descriptor pointer of the process currently running on a CPU from the value of the esp register. ![]()
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