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PMAP_QUICK_ENTER_PAGE(9) BSD Kernel Developer's	ManualPMAP_QUICK_ENTER_PAGE(9)

NAME
     pmap_quick_enter_page, pmap_quick_remove_page -- manage fast, single-page
     kernel address space mappings

SYNOPSIS
     #include <sys/param.h>
     #include <vm/vm.h>
     #include <vm/pmap.h>

     vm_offset_t
     pmap_quick_enter_page(vm_page_t m);

     void
     pmap_quick_remove_page(vm_offset_t	kva);

DESCRIPTION
     The pmap_quick_enter_page() function accepts a single page	m, and enters
     this page into a preallocated address in kernel virtual address (KVA)
     space.  This function is intended for temporary mappings that will	only
     be	used for a very	short period, for example a copy operation on the page
     contents.

     The pmap_quick_remove_page() function removes a mapping previously	cre-
     ated by pmap_quick_enter_page() at	kva, making the	KVA frame used by
     pmap_quick_enter_page() available for reuse.

     On	many architectures, pmap_quick_enter_page() uses a per-CPU pageframe.
     In	those cases, it	must disable preemption	on the local CPU.  The corre-
     sponding call to pmap_quick_remove_page() then re-enables preemption.  It
     is	therefore not safe for machine-independent code	to sleep or perform
     locking operations	while holding these mappings.  Current implementations
     only guarantee the	availability of	a single page for the calling thread,
     so	calls to pmap_quick_enter_page() must not be nested.

     pmap_quick_enter_page() and pmap_quick_remove_page() do not sleep,	and
     pmap_quick_enter_page() always returns a valid address.  It is safe to
     use these functions under all types of locks except spin mutexes.	It is
     also safe to use them in all thread contexts except primary interrupt
     context.

     The page must not be swapped or otherwise reused while the	mapping	is ac-
     tive.  It must be either wired or held, or	it must	belong to an unmanaged
     region such as I/O	device memory.

RETURN VALUES
     The pmap_quick_enter_page() function returns the kernel virtual address
     that is mapped to the page	m.

SEE ALSO
     pmap(9)

AUTHORS
     This manual page was written by Jason A Harmening <jah@FreeBSD.org>.

BSD				August 6, 2015				   BSD

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | AUTHORS

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