NAME
pmap_kextract,
vtophys —
extract a physical address from the
kernel page table
SYNOPSIS
#include
<sys/param.h>
#include <vm/vm.h>
#include <vm/pmap.h>
vm_paddr_t
pmap_kextract(vm_offset_t
va);
vm_paddr_t
vtophys(vm_offset_t va);
DESCRIPTION
The
pmap_kextract()
function retrieves the underlying physical memory address corresponding to
the given kernel virtual address va. The caller is
responsible for ensuring that va belongs to a valid
mapping in the kernel address space. The returned physical address is only
meaningful as long as the mapping remains stable, so the caller must also
have some knowledge or guarantee of the mapping's lifetime. For example, it
is invalid to call pmap_kextract() with the address
of a malloc'd object while there is a possibility for that object to be
freed concurrently.
Unlike
pmap_extract(9),
pmap_kextract()
is safe to be called from any context; it has no internal locking or
sleep.
vtophys()
is an alias for pmap_kextract() and behaves
identically.
RETURN VALUES
The pmap_kextract() function returns the
physical address of memory mapped at the kernel virtual address
va.
pmap_kextract() generally does not fail.
However, if supplied with an illegitimate value for
va, the function may return zero, an invalid non-zero
value, or call
panic(9).
SEE ALSO
AUTHORS
This manual page was written by Mina Galić <FreeBSD@igalic.co>, based on the pmap_extract(9) page written by Bruce M Simpson <bms@spc.org>.