From: Chris Friesen <cfriesen@nortelnetworks.com>
To: Linux kernel <linux-kernel@vger.kernel.org>
Cc: Hugh Dickins <hugh@veritas.com>
Subject: problems with remap_page_range() and virt_to_phys() -- solved
Date: Fri, 10 Sep 2004 15:01:19 -0600 [thread overview]
Message-ID: <4142161F.1060904@nortelnetworks.com> (raw)
In-Reply-To: <4140EEDA.2040909@nortelnetworks.com>
Friesen, Christopher [CAR:VC21:EXCH] wrote:
> The problem that I'm having is that after the call to remap_page_range,
> the result of
>
> virt_to_phys(map_addr)
>
> is not equal to "phys", and I assume it should be since its supposed to
> be pointing to the same physical page as "virt".
I seem to have found my problem. There were two things involved:
1) virt_to_phys() doesn't work on user addresses, so you basically have to walk
the page tables. For ppc, iopa() seems to do this although there is a comment
about it not working on pmac (which it seems to).
2) to setup the vma for unmapped areas I was using mmap with MAP_PRIVATE. On
the first write by userspace, the mapping was changed and the user page was no
longer mapped to the desired kernel page. Changing this to MAP_SHARED fixed it.
Chris
prev parent reply other threads:[~2004-09-10 21:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-10 0:01 having problems with remap_page_range() and virt_to_phys() Chris Friesen
2004-09-10 14:15 ` Hugh Dickins
2004-09-10 15:13 ` Chris Friesen
2004-09-10 17:52 ` Chris Friesen
2004-09-10 21:38 ` Chris Friesen
2004-09-10 21:01 ` Chris Friesen [this message]
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