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Why do we need to have user space and kernel space separated?
Kernel space and user space is the separation of the privileged operating system functions and the restricted user applications. The separation is necessary to prevent user applications from ransacking your computer.
Is it safe for the kernel to directly access user level memory?
Whilst a user-space program is not allowed to access kernel memory, it is possible for the kernel to access user memory. However, the kernel must never execute user-space memory and it must also never access user-space memory without explicit expectation to do so.
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. System calls are requests in a Unix-like operating system by an active process for a service performed by the kernel, such as input/output (I/O) or process creation.
Why do we need kernel and user mode?
A processor in a computer running Windows has two different modes: user mode and kernel mode. The processor switches between the two modes depending on what type of code is running on the processor. Applications run in user mode, and core operating system components run in kernel mode.
What’s the difference between user space and kernel space?
Processes running under the user space have access only to a limited part of memory, whereas the kernel has access to all of the memory. Processes running in user space also don’t have access to the kernel 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.
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.
Why is kernel mode reserved for lowest level functions?
It is reserved for the highest of trusted functions within a system. Kernel mode is generally reserved for the lowest-level, most trusted functions of the operating system. Due to the amount of access the kernel had, any instability within the kernels executing code can result in complete system failure.