INTRODUCTION
What is a kernel ?
A set of code which directly interacts with hardware and allocate and manages resources such as CPU time, memory and I/O access .Kernel also contain system calls which provide specific functions.
HISTORY
The Linux kernel project was started in 1991 by Linus Torvalds as a Minix-like Operating System for his 386. (Linus had originally wanted to name the project Freax, but the now-familiar name is the one that stuck.) The first official release of Linux 1.0 was in March 1994, but it supported only single-processor i386 machines. Just a year later, Linux 1.2 was released (March 1995) and was the first version with support for different hardware platforms (specifically: Alpha, Sparc, and Mips), but still only single-processor models. Linux 2.0 arrived in June of 1996 and also included support for a number of new architectures, but more importantly brought Linux into the world of multi-processor machines (SMP). After 2.0, subsequent major releases have been somewhat slower in coming (Linux 2.2 in January 1999 and 2.4 in January 2001), each revision expanding Linux's support for new hardware and system types as well as boosting scalability. (Linux 2.4 was also notable in being the release that really broke Linux into the desktop space with kernel support for ISA Plug-and-Play, USB, PC Card support, and other additions.) Linux 2.6, released 12/17/03, stands not only to build on these features, but also to be another "major leap" with improved support for both significantly larger systems and significantly smaller ones (PDAs and other devices.)
KERNEL 2.6 FEATURES
Features in kernel 2.6
" Scalability
" Preemptible kernel
" New scheduling algorithm
" Improved threading model
" Hyperthreading
" Module subsystem and device model
" System hardware support
" Block device support
" INPUT/OUTPUT support
" Audio and multimedia
HARDWARE SUPPORT
As Linux has moved forward over the years and into the mainstream, each new iteration of the kernel appeared to be leaps and bounds better than the previous in terms of what types of devices it could support-- both in terms of emerging technologies (USB in 2.4) and older "legacy" technologies (MCA in 2.2). As we arrive at the 2.6 however, the number of major devices that Linux does not support is relatively small. There are few, if any, major branches of the PC hardware universe yet to conquer. It is for that reason that most (but certainly not all) of improvements in i386 hardware support have been to add robustness rather than new features
