vmm Struct Reference

Virtual Memory Manager. More...

#include <vmm.h>

Data Structures
struct	vmm_vma_roots
	Roots of the AVL trees containing the VMAs. More...

Public Member Functions
	BITMAP (reserved, VMM_RESERVED_SIZE/VMA_SIZE)
	Bitmap of the available virtual addreses inside the reserved area. More...

Data Fields
vaddr_t	start
vaddr_t	end
spinlock_t	lock

Detailed Description

A VMM is responsible for managing the allocated virtual addresses within a process.

The VMM splits the address space into distinct regions called Virtual Memory Areas, and keeps track of them individually using AVL trees.

A VMM does not necessarily manage the full 32bits address space, instead it is assigned a start and end addresses, and only keeps track of the regions inside this range.

The VMM uses two different AVL trees to keep track of the VMAs:

• Ordered by address to easily retrieve the area to which an address belongs.
• Ordered by size to retrieve the first fitting area when allocating

Note

The tree ordered by size does not keep track of used areas, since we never need to search for un-free area by size. This avoid modifying the trees more than we need to, since it can be costly.

Member Function Documentation

BITMAP()

vmm::BITMAP	(	reserved	,
		VMM_RESERVED_SIZE/	VMA_SIZE
	)

TODO: Using a bitmap for this takes 2KiB of memory per VMM (so per process)! Is there a less expensive way to keep track of them?

Field Documentation

end

vaddr_t vmm::end

The end of the VMM's assigned range (excluded)

lock

spinlock_t vmm::lock

Used restrict access to the VMM when modifying it

start

vaddr_t vmm::start

The start of the VMM's assigned range

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The documentation for this struct was generated from the following file:

• include/kernel/vmm.h