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.TH VM 9 2023-12-15 "Osmora" "Hyra Operating System"
.Sh NAME
.Nm vm - hyra machine independent virtual memory layer
.Sh SYNOPSIS
.In vm/vm.h
.Sh DESCRIPTION
The Hyra virtual memory subsystem handles various aspects of
virtual memory like memory mapping, keeping track of the virtual
memory context per core, etc.

The term `kernel physical address' will be used to describe physical
addresses that are mapped to the higher half.

The
.Ft VM_HIGHER_HALF
macro points to the higher half of the virtual memory space...
The mapping of kernel physical addresses to virtual addresses are
done with respect to the higher half, i.e., virtual = physical + hddm
(where hddm is the higher half). This cleanly reserves the lower half
of the virtual address space for userspace applications.

The
.Ft PHYS_TO_VIRT
macro converts a kernel physical address to a higher half
virtual address.

The
.Ft VIRT_TO_PHYS
macro converts a higher half virtual address to a kernel
physical address.

.Sh AUTHORS
.An Ian Moffett Aq Mt ian@osmora.org

.Sh SEE ALSO
.Xr dynalloc 9