RE: Sharing memory between kernel and user space

["Brian D. McGrew" <brian@visionpro.com>]

As you recommended I do a __get_free_pages in the kernel and then from
user space I try and mmap the memory.

The mmap is successful but then when I go back and try and read from
that location I get a 'can't read of address 0xbf7c8000 (which is the
address the kernel gave me back).

???

:b!

Brian D. McGrew { brian@visionpro.com || brian@doubledimension.com }
--
> This is a test.  This is only a test!
  Had this been an actual emergency, you would have been
  told to cancel this test and seek professional assistance!
-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of H. Peter Anvin
Sent: Tuesday, May 30, 2006 3:46 PM
To: linux-kernel@vger.kernel.org
Subject: Re: Sharing memory between kernel and user space

Followup to:
<14CFC56C96D8554AA0B8969DB825FEA0012B331A@chicken.machinevisionproducts.
com>
By author:    "Brian D. McGrew" <brian@visionpro.com>
In newsgroup: linux.dev.kernel
>
> I have a question about the best way to share memory between user and
> kernel space.
> 

In general, allocate the memory in kernel space (via get_free_page et
al), and make accessible to userspace via mmap on a device node.

	-hpa
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