forked from PoliEcho-holding-org/kern
21 lines
878 B
Plaintext
21 lines
878 B
Plaintext
Memory Management
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=================
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Memory management is split into three layers: physical, virtual & the heap.
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The **physical memory manager** (PMM) is responsible for allocating physical
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memory. It gives `pmm_*` functions. The `pmm_allocPage()` function allocates a
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4kB page frame and retuns its **physical address**.
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The **virtual memory manager** (VMM) is responsible for allocating virtual
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memory. It provides `vmm_*` functions. The `vmm_alloc()` function takes in a
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number of 4kB pages to allocate and returns the **virtual address** of the
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first page. Userspace can interface with the VMM using the `mmap()` and
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`munmap()` syscalls.
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**The heap** is an area of memory that both kernel and user space have.
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Kernel space uses the `kalloc()` and it's derivative functions for the heap.
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User space may use the `brk()` and `sbrk()` syscalls to grow and shrink the
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heap.
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