From: brace@beardog.cce.hp.com
To: linux-kernel@vger.kernel.org
Cc: brace@beardog.cce.hp.com, scameron@beardog.cce.hp.com
Subject: How to create a kernel virtual mapping for physical addresses.
Date: Fri, 8 Apr 2011 17:03:21 -0500 [thread overview]
Message-ID: <20110408220321.GA777@beardog.cce.hp.com> (raw)
Given a physical address and a length (which may span contiguous pages), how
does one go about creating a virtual mapping for that address? That address may
be in high memory (above 4GB) in a 32bit system.
ioremap() wants a 32bit physical address on 32bit systems. kmap() and
kmap_atomic() wants a struct page which I am not sure how to get from a physical
address.
If there already is a kernel mapping, then using the existing kernel mapping
would be fine if I could figure out how to get it, but if there is not one,
then I need to make one.
I think setting the DMA mask to 32bit would mean that I do not have to deal
with highmem addresses in my particular case, but I still do not know how to
get a virtual address from a physical.
Any suggestions?
Don
next reply other threads:[~2011-04-08 22:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-08 22:03 brace [this message]
2011-04-19 19:51 ` How to create a kernel virtual mapping for physical addresses Arnd Bergmann
[not found] ` <20110421184600.GA29746@beardog.cce.hp.com>
2011-04-21 19:36 ` Arnd Bergmann
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