From: Steven Rostedt <rostedt@goodmis.org>
To: John Wang <john_wang1969@yahoo.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: help on driver's nopage mmap method
Date: Wed, 22 Dec 2004 07:51:11 -0500 [thread overview]
Message-ID: <1103719871.18160.1.camel@localhost.localdomain> (raw)
In-Reply-To: <20041222052322.39048.qmail@web61205.mail.yahoo.com>
On Tue, 2004-12-21 at 21:23 -0800, John Wang wrote:
> Hi, I have been struggling for a couple of days about
> a problem of using nopage method to mmap memory from
> driver to user application.
>
> What I try to do is very simple - just to get the
> simplest case to work, but I always get some junk in
> user app (to be more specific, always 0xFF in the mmap
> the memory area). I don't know what is wrong here - it
> appears perfectly normal (compared to the examples in
> the book Linux Device Driver). The kernel is 2.4.2
> running on Intel x86 platform.
>
> The program is very simple so I attached here (header
> includes are ignored here to shorten the length).
> Please CC me directly if anyone has answer since I am
> not subscribed to the mailing list. Thanks in advance.
I just tried your program on both 2.4.20 and 2.6.9 and it works fine.
Kernel 2.4.2 is very old, you might want to try a different kernel.
-- Steve
prev parent reply other threads:[~2004-12-22 12:51 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-22 5:23 John Wang
2004-12-22 12:51 ` Steven Rostedt [this message]
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