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Date: Mon, 15 Oct 2001 11:12:19 -0500
From: Tommy Reynolds <reynolds@redhat.com>
To: ptb@it.uc3m.es
Cc: linux-kernel@vger.kernel.org
Subject: Re: share buffer between user and kernel?
Message-Id: <20011015111219.4cd14672.reynolds@redhat.com>
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Organization: Red Hat Software, Inc. / Embedded Development
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It was a dark and stormy night.  Suddenly "Peter T. Breuer" <ptb@it.uc3m.es> spoke:

> What is the currently approved method of sharing a buffer between
> user space and kernel space, so that I can avoid one or two
> copy_to/from_user?

Two basic choices here:

1) Allocate the buffer in kernel space and use the mmap() method to give the
user-space program access to it; and

2) Allocate the buffer in you user application program and use the KIOBUF method
to give the kernel and/or hardware access to your buffer.  Look in
<linux/iobuf.h> for kernel-level inspiration.

---------------------------------------------+-----------------------------
Tommy Reynolds                               | mailto:	<reynolds@redhat.com>
Red Hat, Inc., Embedded Development Services | Phone:  +1.256.704.9286
307 Wynn Drive NW, Huntsville, AL 35805 USA  | FAX:    +1.236.837.3839
Senior Software Developer                    | Mobile: +1.919.641.2923
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