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Date:      Wed, 21 Mar 2001 17:32:55 -0800
From:      Chris Sears <cbsears@ix.netcom.com>
To:        freebsd-hackers@freebsd.org
Subject:   Re: Linux -> FreeBSD VM functions
Message-ID:  <3AB95647.B8F646DE@ix.netcom.com>
References:  <200103212251.f2LMpah02805@mass.dis.org>

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Mike

> 
> FreeBSD provides a more complete mechanism for getting virtual mappings
> of device physical apertures, and you should use it.
> 
> > No actually it would the other way around: VM_PAGE_TO_PHYS.
> > But you have to get the vm_page of the virtual address first.
> > Perhaps pmap_extract(pmap, va) might be more helpful
> > but you will need the pmap of the process.
> 
> Typically, in non-PCI, non-PNP cases you would use pmap_mapdev().

He was looking for virtual to physical mapping rather than allocation.
pmap_mapdev allocates:

/*
 * Map a set of physical memory pages into the kernel virtual
 * address space. Return a pointer to where it is mapped. This
 * routine is intended to be used for mapping device memory,
 * NOT real memory. The non-cacheable bits are set on each
 * mapped page.
 */

But in any case, he should hit the books.

Chris

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