From: Russell King <rmk@arm.linux.org.uk>
To: Armin Schindler <mac@melware.de>
Cc: "Ingo Molnar" <mingo@elte.hu>,
Êæ¹úÇ¿ <guoqiang@intec.iscas.ac.cn>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Question about ioremap and io_remap_page_range
Date: Thu, 27 Sep 2001 09:16:01 +0100 [thread overview]
Message-ID: <20010927091601.A6499@flint.arm.linux.org.uk> (raw)
In-Reply-To: <Pine.LNX.4.33.0109270847070.2745-100000@localhost.localdomain> <Pine.LNX.4.31.0109271001001.25611-100000@phoenix.one.melware.de>
In-Reply-To: <Pine.LNX.4.31.0109271001001.25611-100000@phoenix.one.melware.de>; from mac@melware.de on Thu, Sep 27, 2001 at 10:03:26AM +0200
On Thu, Sep 27, 2001 at 10:03:26AM +0200, Armin Schindler wrote:
> virt_to_phys() is obsolete ? What should be used if I need the phys address
> of a memory page ? (e.g. for mmap() remapping)
virt_to_phys is only valid on the kernel direct mapped RAM area - memory
returned from kmalloc and non-highmem memory returned from get_free_page.
Since vmalloc and ioremap do not return a pointer into the direct mapped
RAM area, but its own mapping, it is not valid to use virt_to_phys on
these returned values, even through it might be a virtual address.
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
next prev parent reply other threads:[~2001-09-27 8:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-09-27 6:04 Question about ioremap and io_remap_page_range 舒国强
2001-09-27 6:52 ` Ingo Molnar
2001-09-27 8:03 ` Armin Schindler
2001-09-27 8:14 ` David S. Miller
2001-09-27 8:16 ` Russell King [this message]
2001-09-27 14:33 ` Jonathan Corbet
2001-09-27 17:42 ` Jonathan Lundell
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