It's common among operating systems to use a dedicated area of memory called Stack Memory, which works similarly to the stack used in the CPU (with a stack pointer register and a base pointer register).
I know that in the case of some CPUs, the stack pointer has a specific memory range that can be addressed (for example, some chips only allow RSP addresses from 0x00 to 0xff).
When we talk about the OS, all processes have a stack block that works identically. It grows upward and work as a Last-In-First-Out (LIFO) structure. Stack accesses are faster than heap accesses because they are located at the beginning of the memory range and are sequential.
My question is: Is the stack in OS processes an abstraction created to facilitate process swapping in the CPU by keeping track of the current state of the process execution in the process stack area and only changing the stack pointer to another process's stack? Or are they completely different?
If they are similar, can the stack pointer on CPUs address the entire memory, or does the OS divide the available addressable memory among processes?
The stack used by processes in an operating system and the stack pointer used by CPUs are related concepts but operate at different levels of abstraction.
Here is how:
The CPU stack pointer (such as the RSP register in x86 architecture) is a hardware register that points to the top of the stack in the CPU's memory. It is used for managing function calls and local variables within a single execution thread. The stack pointer is limited to the addressable memory range of the CPU, and it typically operates in the lower region of the memory address space.
On the other hand, the stack used by processes in an operating system is an abstraction created by the operating system to facilitate memory management and process execution. Each process has its own dedicated stack, separate from the CPU's stack. The process stack provides a region of memory for the process to store local variables, function call information, return addresses, and other data related to the execution of the process.
The operating system manages the process stack as part of its memory management responsibilities. When a process is created, the operating system allocates a portion of the addressable memory space to that process's stack. The size of the stack is typically fixed or configurable per process and is typically located in the higher memory address range.
The process stack is used to store information for function calls and to keep track of the current state of execution within the process. When a process is swapped in or out of the CPU by the operating system scheduler, the stack pointer is updated to point to the appropriate stack for the currently executing process.
So, while the CPU stack pointer and the process stack are related concepts, they operate at different levels of abstraction. The CPU stack pointer is limited to the addressable memory range of the CPU, whereas the process stack is managed by the operating system and is typically located in the higher memory address range, separate from the CPU's stack. The operating system is responsible for dividing the available memory among processes and managing their respective stacks.
The stack pointer on CPUs typically operates within a specific memory range and does not address the entire memory. The size of this range is determined by the architecture and design of the CPU.