What is kernel space VS user space?
Kernel space is strictly reserved for running a privileged operating system kernel, kernel extensions, and most device drivers. In contrast, user space is the memory area where application software and some drivers execute.
How is kernel space and user space interface?
3.2 Kernel and user space The kernel provides certain services, and user space, that is, everything outside the kernel, both libraries and application programs, uses these. Programs in user space contain system calls that ask the kernel to do something, and the kernel does so, or returns an error code.
What is user address space and kernel address space?
Kernel space is that area of virtual memory where kernel processes will run and user space is that area of virtual memory where user processes will be running. This division is required for memory access protections.
Is kernel space in RAM?
The code for managing all this hardware – all the shared resources, as well as process scheduling and memory management – is located in main memory and belongs to the oper- ating system. This part of the main memory is what is commonly referred to as kernel space.
Why do we need kernel space?
kernel space and user space is about the system protection, to make the system more robust. kernel space is privileged mode and can do things (like directly interacting with hardware/system resources) which user space cannot. All the user space interaction with the hardware has to go through kernel space only.
What is kernel space?
Kernel space is where the kernel (i.e., the core of the operating system) executes (i.e., runs) and provides its services.” – Kernel Space Definition, The Linux Information Project 2005. As the quote above states, kernel space is a term used to describe a part of the computer’s memory.
What are user services and kernel services?
The user services are kept in user address space, and kernel services are kept under kernel address space, thus also reduces the size of kernel and size of an operating system as well. It provides minimal services of process and memory management.
Where is kernel address space?
The operating system supports a flat 32-bit virtual address space. The bottom 2 GB of the address space is for user processes, while the top 2 GB is for the kernel. The kernel address space is statically mapped into the address space.
What causes a context switch from userspace to kernel space?
System calls (which includes accessing devices) also causes a context switch from userspace to kernel space.
What is the kernel module used for?
This kernel module needs to receive tasks issued by a user space program, and send results back to user space program after completion. The user space program should be blocked while the kernel module is doing its job.
What is the fastest way to transfer data between kernel and userspace?
However, if you want to transfer large amounts of data to and fro the kernel, then you can look at using netlink sockets or use mmap which is probably the fastest mechanism for transferring data although you will have to implement your own notification mechanism to inform the userspace program when data is ready and vice-versa (for consumption).
How to communicate between two userspace programs in a module?
The easiest is to use the proc file interface to communicate, especially if the message and the result are less than one page in size. Open and close can implement locking so that only one instance of userspace program can actually access the module request engine.