From: anish198519851985@gmail.com (anish singh)
To: kernelnewbies@lists.kernelnewbies.org
Subject: Can we map a device address to two different memory locations?
Date: Fri, 27 May 2011 23:18:05 +0530 [thread overview]
Message-ID: <BANLkTimVuyrpv0EKRWRN3QkXsJcJAF_rcQ@mail.gmail.com> (raw)
In-Reply-To: <BANLkTimuYGkCEQ0nnKuivJS5uZO5WXq68g@mail.gmail.com>
On Fri, May 27, 2011 at 10:54 PM, Mulyadi Santosa <mulyadi.santosa@gmail.com
> wrote:
> Hi...
>
> On Fri, May 27, 2011 at 17:49, sandeep kumar <coolsandyforyou@gmail.com>
> wrote:
> > Now the question is can we memory map a one device resource(say some
> > iomemory) to two different memory locations?
> > the other way of seeing at this question is,
> > Will ioremap() gives different 'virtual addresses' when called multiple
> > times?
>
> I agree with Daniel, but I suggest you to think about it: in reading
> operation, maybe it's ok, no concurrency issues need to be taken
> care...but how about writing? unless we're sure they are atomically or
> uninterruptible, i see a chance that race condition might happen here.
>
> Actually it's similar when you map a file into two different VMA and
> write into it, correct?
>
Don't you think it would also be reducing the memory map space in RAM
which is a critical resource and many other drivers would be denied
the mapping of there IO resources?
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
>
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next prev parent reply other threads:[~2011-05-27 17:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-27 10:49 Can we map a device address to two different memory locations? sandeep kumar
2011-05-27 15:34 ` Daniel Baluta
2011-05-27 17:24 ` Mulyadi Santosa
2011-05-27 17:48 ` anish singh [this message]
2011-05-27 18:01 ` Mulyadi Santosa
2011-05-28 12:24 ` Peter Teoh
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