User and Kernel level Threads:
Kernel Thread executes in kernel mode. and user-level thread executes in user mode.
OS has control of Kernal mode and user have control on user mode.
How user mode communicates with kernel mode?
|kernel level thread||User level thread|
|Recognized by the operating system.||Does not recognized by the operating system.|
|Implemented by the operating system.||Implemented by a user of the system.|
|Implementation is complex.||Implementation is simple and easy.|
|Solaris is an example||Posix is an example|
|Requires hardware support||Requires no hardware support|