How does user space and kernel space communication?
Communication between user-space and kernel space using Netlink sockets. Netlink is used to transfer information between the kernel and userspace processes. It consists of a standard sockets-based interface for user space processes and an internal kernel API for kernel modules.
What is user space and kernel space program?
The user space, which is a set of locations where normal user processes run (i.e everything other than the kernel). The role of the kernel is to manage applications running in this space from messing with each other, and the machine.
How do you send a signal from kernel space to user space?
ksig – sending signals from the kernel space to the user space
- siginfo. Signal is eventually the struct siginfo in the kernel code.
- debugfs. As the user space routine, the kernel has to know the pid of target process before sending a signal.
- task, send_sig_info()
What is Netlink socket in Linux?
The Netlink socket family is a Linux kernel interface used for inter-process communication (IPC) between both the kernel and userspace processes, and between different userspace processes, in a way similar to the Unix domain sockets.
Who established communication between user and kernel in Linux?
Then, Alexey Kuznetsov extended it during Linux kernel 2.1 development to provide a flexible and extensible messaging interface to the new advanced routing infrastructure. Since then, Netlink sockets have become one of the main interfaces that kernel subsystems provide to user-space applications in Linux.
Can kernel can access user address space?
Code running in kernel mode has access to both user space and system space. That is, code running in kernel mode has access to system space and the virtual address space of the current user-mode process.
Is Netlink obsolete?
Netlink was first provided in the 2.0 series of the Linux kernel, implemented as a character device. By 2013, this interface is obsolete, but still forms an ioctl communication method; compare the use of rtnetlink .
Why is it important to keep the kernel separated from user space?
Separating the spaces is not strictly necessary, but if you need to protect OS structures from user code to prevent wrong or bad manipulation of them, then you need some kind protection. Otherwise such bad manipulations would break OS inner coherence which is usually something you don’t want.
How are user space processes access the kernel?
User space processes can only access a small part of the kernel via an interface exposed by the kernel – the system calls. If a process performs a system call, a software interrupt is sent to the kernel, which then dispatches the appropriate interrupt handler and continues its work after the handler has finished.
How are signals managed by the OS kernel?
Signals usually initiated by a process (kill ()) or the OS kernel (e.g: SIGFPE, SIGSEGV, SIGIO).They are managed by the OS kernel, which delivers them to the target thread/process, invoking either a generic action (ignore, terminate, terminate and dump core) or a process-provided signal handler.
How is the memory mapped to the kernel in Linux?
The way linux used to work (and still does on systems where the memory is small compared to the address space) was that the whole of physical memory was permanently mapped into the kernel part of the address space.
What is the role of the kernel in Linux?
The role of the kernel is to manage applications running in this space from messing with each other, and the machine. The kernel space, which is the location where the code of the kernel is stored, and executes under.